: OTA FAQ & Knowledge Base
2003-03-17, 02:28 PM
* What does this OTA FAQ cover? The purpose of this FAQ is to provide a fundamental introduction to all aspects of OTA, as well as to introduced readers to the amazing depth and variety of great information in the Digital Home OTA Forum discussion threads. You are currently reading Post #1 of the OTA FAQ, which is followed by over twenty more FAQ posts that cover various distinct areas of OTA knowledge.
* What does OTA mean? It stands for Over The Air television reception, as has been available free-of-charge in Canada since the early 1950s using antennas for reception. OTA is not to be confused with FTA, which is a form of satellite TV reception using entirely different gear.
* Why are we switching from analogue to digital TV? Analogue TV (also known as NTSC) is the original television standard in North America and it has served well for many decades but is prone to many different kinds of interference that can make viewing troublesome for consumers. The newer digital standard called ATSC (also known as DTV, for "Digital Television") eliminates almost all of that interference, as illustrated in this split-screen video made by recneps77:http://www.youtube.com/watch?v=ebgDmevXUkg broadcasting DTV requires much less transmitter power to cover the same area as analogue
for consumers the availability of High Definition TV via OTA antenna is only possible via ATSC DTV
the U.S. has converted their old analogue transmitters to DTV as of June 12, 2009 although a few low-power stations were exempted and remained on NTSC
Canada set its date for full DTV conversion to August 31, 2011 although some low-power stations were exempted and remained on NTSC
Canada uses the ATSC (8VSB) standard used in the U.S.A., Mexico, South Korea, and Taiwan, with more Western Hemisphere nations expected ATSC is not compatible with the DVB-T standard used in all other countries except Japan, which has its own ISDB-T standard, and China, which has its own DTMB standard.
* Is OTA expensive? In an ongoing poll of DHC OTA users (http://www.digitalhome.ca/forum/showthread.php?t=32189), the great majority have paid less than $500 Canadian for all the OTA gear they required. Less than 1% paid more than $1,000. Some have canceled some or all of their satellite or cable programming, so their OTA equipment will pay for itself in savings over time. There are no direct costs or fees to the consumer for OTA programming.
* Are there OTA stations in my area? The OTA Forum has a sub-forum called Reception Results (http://www.digitalhome.ca/forum/forumdisplay.php?f=129) which features a thread for every section of Canada. Read through the thread for your own area and if necessary the surrounding area(s) to see what DHCers have already reported. A vast amount of experience and trial & error has gone into those threads, so please read through yours from the beginning. See Post #10 in this OTA FAQ to learn how to use a variety of online tools for best aiming of your OTA antenna for the stations in your area.
* Will I get stations from more than one city? TV antennas need to be pointed at the broadcast antenna, so if the cities are fairly well lined up in one direction, aim an antenna and enjoy. If you are fairly evenly between two locations there are antennas that receive front and back simultaneously. If the cities are wide apart, mount the antenna on a rotor. You can program the rotor's remote control to turn the antenna into proper position, which will usually take less than 30 seconds. Some DHCers have used 2 or more antennas aimed in different directions rather than a rotor. See Post #16 in this FAQ for info on how to combine 2 or more antennas.
* What if the stations are far away? TV signals typically start to drop off in strength as they travel about 120 to 180 km outwards from the broadcast antenna, so reception in those deep fringe and deepest fringe areas requires special antennas, gear, and installation techniques as you reach or exceed the higher distances. Expert help is available to you by discussing your situation in the Reception Results thread for your area.
* Will my TV get the Digital OTA stations? Check to see that it has an ATSC Tuner. Many, if not most, older TVs have NTSC-only tuners, which will not receive DTV stations. For those NTSC-only TVs a consumer can use a converter box to feed ATSC signals to them in the lower-grade NTSC format. See Post #17 in this FAQ for more detail on ATSC tuners found in set top boxes, HDTVs, and other equipment.
* Okay, which antenna do I need? The DHC OTA Forum contains detailed threads about different OTA antenna brands and models. See also Post #3 in this FAQ for antenna buying tips, and also be sure to download the Antenna Decision Chart (PDF) (http://www.digitalhome.ca/forum/showthread.php?t=97121). You will likely need to do some reading in the OTA Forum to understand the rankings and other criteria in the chart. Keep in mind that just because a competing-brand antenna looks a lot like a leading brand antenna does not mean that it performs the same - there can be significant performance differences. Stick to our advice on brand and model recommendations and you will not go wrong! If its not on the chart, don't buy it. Also see Post #3 in this FAQ for essential Antenna buying and planning tips.
* I'm pretty handy with tools. Can I build my own antenna? Absolutely yes, and in Post #11 of this FAQ you'll find info on best plans, techniques, materials, and other great info for Do It Yourselfers, including how to use computer modeling software for antenna design. The DHC OTA Forum is the one and only home of the Gray-Hoverman and Stealth Hawk (http://www.digitalhome.ca/forum/showthread.php?t=140206) do-it-yourself antenna projects, which have created powerful home built super antennas for OTA TV reception that routinely outperform most commercial antenna models.
* Some new antennas look the same as my grandfather's old one! Aren't they old fashioned? No, TV antenna technology is essentially the same as it has been for several decades because the laws of electromagnetism and physics apply equally now as they did then. Today some manufacturers are finding clever ways to cram antennas into small form factors, but unfortunately due to those laws of nature the antenna's performance drops the more they try that. Manufacturers now have modern materials to work with so the construction of their products seems to be more durable, but antennas have often lasted more than 20 years. Since TV antennas have been around so long, there is already a large body of real world knowledge about antenna designs and capabilities. See Post #5 in this FAQ for an explanation of how TV antennas actually work.
* Which other OTA equipment will I need? There may be conditions affecting your reception that require specific equipment, such as preamps, attenuators, distribution amplifiers, splitters, combiners, a tower, etc. If you try such equipment without proper knowledge or guidance you could damage your TV and other equipment. The OTA Forum is the right place to ask the experts. See Post #14 in this FAQ for further info.
* Aren't Satellite and Cable TV better than OTA TV? For specialty channels and pay-per-view movies and events, Satellite or Cable TV are needed because such channels as TSN and Discovery HD are not broadcast OTA. However, if you want regular, local programming, OTA is free of charge or fee to the consumer. The only cost you will pay is for the gear itself and any taxes on it.
With a top quality OTA receiver and antenna gear, the improvement in picture and audio quality over Cable TV or Satellite can be spectacular, especially in HDTV, as many DHCers attest. This is not conjecture; the improvement is readily visible and audible on good systems, especially when seen in split-screen mode.
Some consumers will want to have the best of both: keeping their Sattelite or Cable TV subscriptions and watching their favourite programming OTA.
Some will find no reason to use OTA because they find the quality of their TV reception by other means is satisfactory to them.
Some will find that using OTA is not possible due to certain local situations, and so will rely on either Satellite (if they can aim a dish correctly from their location) or Cable TV if it is available
Some will find going 100% OTA to be the most worthwhile solution, while watching first run movies and specials via Internet providers like Netflix, Hulu, and Qriocity, or by DVD/BluRay rental from video stores.
If you are planning a move to another city, Cable TV set top boxes from one Cable company almost always do not work with the systems of different Cable companies; Satellite gear can be moved anywhere that the dish can be aimed succesfully, and OTA gear works fine as long as stations are available. Some CATV subscribers have had their FM radio service dropped by their providers. With an OTA VHF/FM antenna there are not only analogue FM radio stations available but also many HD Radio stations in border areas carrying digital audio that rivals CDs for quality.If you have an ATSC tuner in your TV and live in a suitable area, what's the harm in hooking up an antenna and seeing OTA for yourself? Even so, suit yourself and respect the decisions of others. You can discuss these issues in the Pros & Cons of Going OTA thread (http://www.digitalhome.ca/forum/showthread.php?t=32200).
* Does Digital OTA TV have an On Screen Guide? Yes, the ATSC standard incorporates a data standard called PSIP, which contains program, channel, time, and other data for the ATSC tuner to display. There are also several Third Party program guides available, such as TVGOS, TitanTV, Schedules Direct, and others. See this thread about OTA On-Screen & Third Party Electronic Program Guides (http://www.digitalhome.ca/forum/showthread.php?t=117315).
* Why is everything here named in letters that I don't understand? See the DHC FAQ regarding Acronyms & Definitions (http://www.digitalhome.ca/forum/showthread.php?t=17715)
* What does DX mean? Here in the OTA forum we sometimes use the term DX, which some say means "Dial Crossing". DXing has been a hobby of enthusiasts going back to the early days of radio and now of television. DXers enjoy scanning broadcast frequencies in search of unusual or long distance signals, such as during odd weather conditions. Thus, DXers are very knowledgeable about high quality equipment and the techniques needed. Many TV DXers are also ham radio enthusiasts.
* Isn't all this OTA stuff illegal, like satellite piracy? NO! OTA television reception is the original form of television broadcasting and is 100% legal as always. See Post #13 in this FAQ for further information about the legality of OTA.
* Is all this great OTA info free?This web site, www.digitalhome.ca (http://www.digitalhome.ca/), is a private business. It cannot survive on bread alone. Please register as a member at our site (http://www.digitalhome.ca/forum/register.php), at no cost to you.
While we are happy to share our information here with other members and with guest viewers, this site asserts and respects copyright laws and we take a very dim view of plagiarism of our material. Please report sites that misuse our contents.
Advertisers are very welcome to contact the owner, and here's what consumers can do: whenever you contact any OTA-related company, station, network, supplier, vendor, installer, technician, marketing person, representative, or other corporate person, be sure to tell them about this site and that their advertising support here would be most welcome. Here's an example:"Yes, I'm calling about your station's schedule to start up its digital transmitter. I read about it on the Digital Home website... have you visited that site before? Here's the URL..."
Also, please consider selecting one of our Paid Membership options. Please help us keep this web site going strong. Help us to help you. (http://www.digitalhome.ca/forum/payments.php)
Please proceed to Post #2 in the OTA FAQ
2005-06-28, 04:42 PM
Why can't there be one simple OTA setup for everyone?This has been said many times before in different variations, but I'll repeat it now for the benefit of everyone. The type of antenna is just one variable in the reception mix for OTA.
These variables combined make every single OTA set-up unique.
For example, even in my house my reception is different in the basement than in the kitchen because the signal has to travel first to the basement for the HDTV, and then loop-out to the kitchen (for analogue).
Some variables that you have control over, or at least will vary between users in similar locations:
Location of your antenna (indoor/outdoor)
Height, direction, angle, & gain (type) of your antenna
Length and type of cabling used (RG6/RG59/Twin Lead, etc)
Whether or not a signal amplifer (pre-amp/distribution/booster) is needed/used and its proximity to the antenna.
Local effects on your antenna: obstacles and reflective surfaces (buildings/trees/structures).
Whether the antenna is fixed or on a rotor
Age of the OTA Gear (new, used, ancient)
Capablilties of your tuner (newer tuners have higher gain and are better at rejecting mulitpath interference)
Some of the other variables you can't control and affect all users (though not equally) such as:
Broadcast antenna height/power/distance/direction/contour
Why can't you just post a list of all the OTA stations I can get in my area?
Listing a bunch of stations is easy but not very realistic or helpful to readers because reception conditions are very local, even between houses on the same street if one is up high and the other is quite a ways downhill. The approach at this web site is to provide information that is extremely local to a person's location. We use Reception Results threads for every part of Canada rather than general lists that usually are not satisfactory. Over about five years we have accumulated Reception Results from people living all across Canada, so now the general expectation of what a person can receive has become clear for most major centres and populated areas. Unfortunately in some areas on the fringe of reception from DTV stations we just don't have very many user experiences to rely on. With time this will change, and we are grateful for the pioneers out there. :)
Five years ago we had almost no knowledge, experience, or factual information on how DTV reception in various parts of Canada would be. DTV was still very new so even the stations themselves were changing and improving all along, so that what a person found out one day would be different a week later. As of the middle of 2009 we are still fairly early on in the Canadian DTV conversion process, with about 30 operational DTV stations spread across several major cities. Canadians in border areas get a wide variety of U.S. DTV stations but the status of those stations has been changing frequently due to the June, 2009 U.S. DTV conversion.
Will I be able to just "set and forget" my OTA gear? If I need to change it can I get help with keeping my OTA system at its best?
Yes to both questions, but in all honesty TV stations change over time, and we do our best to keep our readers up to date. With members who are station employees and in other broadcasting positions we often get the news before anyone else does. :) Your OTA system may or may not need optimizing in the future to deal with changing situations, and here is a good example of a "power OTA user" and his evolving system:I have been lurking “Digital Home” and several other sites for few years now. I only started contributing to this forum earlier this year and thought I would share some of my past experiences, in hope it might help others as more people are starting to discover digital OTA reception.
Since I went HD three ago years, I originally installed CM 4228 and CM 9521A rotor and have had very good results with it. I was able to receive all the stations available at that time, to this date.
Here are some of the challenges I had to deal with my installation, our home was basically located in a hole. I would have to stand on my tipi-toes if I wanted to have a chance even to see the CN Tower, if you know what mean. When I look south and west all I could see were trees and that’s standing on the roof top of our two story house. Of course I had to deal with all the other good things like bad weather etc.
At end of last year I starting playing with combining antennas like many of you are doing or already have. If you look back at some of previous postings you might see how my setup has evolved overtime.
To-date my setup consists of 4228 + 4221 (mounted the 4221 within an inch of each other fortunately it did not have any real detrimental effects) and a rotor, three distribution amplifiers four dual splitters and two 4way splitters, attenuators etc. With this arrangement I was able to receive all twenty five digital plus the additional analog channels. Distributing a good signal to eight TV’s or more throughout the house, similar to “cable TV” connection. Of course it still suffers the typical signal dropouts, as result of poor weather conditions, fog etc. A couple months ago Channel 7.3 stopped broadcasting sports and I have notice they have now shut down the carrier as well so were down to 24 channels.
I have had a lot fun and gratification, putting this together. Experienced many interesting problems from, ( similar to what many of others have in the forum) signal overload on one channel on one TV, to distributing a right signal level to each individual tuner throughout the house. Unfortunately all the tuners don’t have the same characteristics, as it might make life a little easier. At one point earlier this year I had two rotors now that was great learning experience, it was very handy (especially in winter “no fun climbing two story house”). I even tried three antennas, but found that two were sufficient. I still use my rotor for (testing) fine tuning for bad atmospheric conditions. Some other members have posted, that they have found combining antennas quite simple that’s great, but this is just my experience. I know that what works for me, may not work for all, every installation has own unique problems.
When I look back I always have a fond memories, of just the “4228 and rotor” it was relatively simple setup and worked for a couple years for me. I am pretty sure in "general" it would work for many other Mississaugan’s and others in the GTA.
I am looking forward to the future hopefully the CTRC approves more stations. It would be nice if TVO goes digital, but for now I am just sitting back and enjoying!
BTW. I have really have appreciated reading all the posting on this forum, thanks to all.
2005-11-16, 03:12 PM
Do you have some antenna buying tips?Antennas are designed along well known electromagnetic principles that predate HD, SD, DTV, etc. by almost a half century. Any vendor that claims that a particular antenna model is "better for HD" etc. etc. is full of it. Don't pay attention to that misleading sales & marketing nonsense. The original Channel Master 4228, for instance, is one of the highest rated UHF antennas out there today for all analogue and digital reception, yet its design is about 30 years old! Channel Master has replaced it with the 4228HD, which may mislead people into believing that it is better for HD when in fact independent research proves that it is weaker than the original that it replaced.
Avoid the hype... just the facts, ma'am.
In some central urban areas, such as atop a high rise in downtown Toronto, a set of cheap Canadian Tire rabbit ears might do the job if you just want the local digital and analogue stations, but in other urban areas, rural locales, and deep fringe areas there are a lot of things to consider before purchasing a TV antenna.
Keep in mind that TV antenna technology is essentially the same as it has been for several decades since the laws of electromagnetism and physics apply equally then as now, so this means we are fortunate that there is a body of real world knowledge and evidence about antenna designs and capabilities if you know whom to ask. There are enough real world examples out there for the experts to give you the best advice and save you a lot of trouble. Advice can be found here in the OTA Forum for those difficult situations or possibly pricey decisions. Don't be timid about asking newbie questions.
So, avoid impulse buys based on advertising claims (especially about reception range!) and ignore any claims of an antenna being "Digital Ready" or "HD Compatible" because those terms mean nothing. Never, never buy an antenna because it "looks great" on top of your TV. Getting the best reception is what its all about.Essential buying and planning tips for OTA antennas:
All OTA antennas are "digital ready" and "HDTV ready" (ignore those marketing words)
TV antennas of every kind just pick up signals whether they are broadcast in digital or analogue form
in theory reception of equal strength analogue signals versus digital signals (all other things being equal too) would therefore be exactly the same
in the real world many issues unrelated to the antenna can make such signals differ, as discussed in this OTA FAQ
the antenna itself handles both types equally
Mount antennas outdoors and as high as possible, free from obstructions
Attic or indoor mounting can present reception problems due to signal losses so they should be a last option
Most DTV stations are in the UHF band but some are in VHF
VHF and UHF antennas are different in size and shape because they receive different frequency bands
VHF has 2 bands:
VHF-LO contains channels 2 through 6 (54 to 88 Megahertz) requiring a huge antenna
VHF-HI contains channels 7 through 13 (174 to 216 MHz) requiring a large antenna
FM Radio (88 to 108 MHz) is in between VHF-LO and VHF HI so most VHF TV antennas are also excellent FM Radio antennas, referred to as VHF/FM and capable of also receiving HD Radio (Hybrid Digital) FM stations in CD audio quality from U.S. border areas
UHF band contains channels 14 through 69 (470 to 806 MHz) requiring a relatively small antenna
Combo antennas feature a UHF and a VHF on one spar
For consumers a Combo offers good performance with simpler installation and less room on the mast
Pros and OTA hobbyists prefer the performance of separate UHF and VHF/FM antennas rather than a Combo
Satellite Dishes cannot be used to receive OTA signals because they operate on totally different frequencies
Is there a warning list of OTA stuff that I should never buy?Yes, there is a humourous thread called Wacky, Tacky OTA Gear (What NOT To Buy!) (http://www.digitalhome.ca/forum/showthread.php?t=35083) that is well worth reading to help you avoid wasting your money on junk and OTA gear NOT to buy. Avoid gimmic antennas such as the ill-conceived Terk 55, the fraudulent Xium Air, or the ones that promise to turn your household AC wiring or aluminum eaves troughs into a TV antenna. Additionally, the OTA Clone & Coat Hanger Antennas - Avoid Most Of Them (http://www.digitalhome.ca/forum/showthread.php?t=106108) thread warns of cheap "clone" antennas that may look like high performance models but are usually poor performers.
If you are unsure about a product, the OTA Forum has many threads that deal with specific items and/or brands in which you can read or offer advice. A fool and his money are soon parted.Can I just go to my local consumer electronics store for OTA stuff?Yes, some of those stores have some OTA equipment and OTA-savvy knowledgeable staff, but in Canada it generally seems that retail salespeople do not tend to be well briefed on Digital OTA. You can read through the Popularizing OTA HDTV In Canada (http://www.digitalhome.ca/forum/showthread.php?t=40900) thread to get a better understanding of the OTA popular awareness situation. For this reason we recommend dedicated, knowledgeable OTA vendors for your parts, sales, service, and installations.Is it okay to use an old antenna?Oxidation may be a problem on many old antennas if it is causing welded or soldered joints to fail. If your antenna is still solidly constructed you are fine to clean it with steel wool. I would use something like an SOS or Jet pad for that. Clean the feed points too (where the balun is connected) and replace the old wingnuts or screws with new ones.
As for reception, oxidation will reduce the antenna's effectiveness but it would happen over a long time from when it was new, not suddenly. If you were to take a perfectly new version of the same antenna and compare it side-by-side with your older one you might see some difference in the resulting signal strength, but not at a worrisome level. I have an old-timer 4-bay bowtie reflector on my roof that was almost white with oxidation but I did not hesitate to use it after a cleanup and it works beautifully.Can I put up my own antenna?Absolutely, and Post #21 of this FAQ gives a variety of useful tips and links to discussion threads about important antenna installation topics. For those who do not wish to put up their own antenna and OTA gear, experienced, professional installers can be found in almost any part of Canada and the United States.An Overview of Various Antenna TypesAs you read through your printed-out Antenna Chart (http://www.digitalhome.ca/forum/showthread.php?t=97121), here is further info on the most highly regarded consumer antennas. If you cannot locate one for purchase, try to find the next highest one rated on the Antenna Chart:
VHF/FM-Only: does not receive UHF stations but receives locally available VHF TV Channels 2 through 13 and FM Radio stations
VHF-HI-Only: receives locally available VHF-HI TV Channels 7 through 13
VHF/FM/UHF: is called a "Combo" and is capable of receiving all locally available TV channels and FM Radio stations
VHF/FM/UHF Deepest Fringe: It is best to leave this category to pros or experienced OTA hobbyists. Mount 2 UHF antennas in stacked configuration (see Post #16 in this FAQ) with a VHF/FM, feeding them into a high-gain all channel preamp atop a minimum 20 foot tower or similar elevation with unimpeded signal from the target. A heavy duty rotor and/or mount is advised due to the weight and wind load. NOTE: A Deepest Fringe setup is NOT suitable for closer use because its great reception power can overload and/or damage amps, TVs, and receivers if proper safeguards are not in place.http://www.digitalhome.ca/forum/picture.php?albumid=260&pictureid=9154
Metro/Suburban, Condo, RV, or Apartment:
Outdoor antenna products like the costly Winegard Square Shooter, the Super Delhi, the pricey Antennas Direct Lacrosse, or the Channel Master 3010A-Stealth antennas have been introduced to be esthetically suitable (smaller) although they are often no match beyond the near fringe range for mainstream antenna gear.
UFO-style omnidirectional antennas like the Antennacraft 5MS921 Omni-State, Winegard MetroStar, or Channel Master SmartTenna are useful on Recreational Vehicles and boats, but are prone to suffer from multipath signal interference more than standard antennas. In Canada the one and only location in which I would consider a UFO antenna as a viable alternative to a standard antenna is in the central and northern part of the Niagara Peninsula in Ontario since the Toronto, Hamilton, and Buffalo stations surround the area and are relatively equal in signal strength.
Clip-on satellite dish OTA antennas rarely offer anything but extremely local performance so should be avoided.
Indoor Antennas: See Post #6 in this FAQ
UHF-Only: See the section immediately below.
UHF-Only AntennasHere's what the antenna pros have found over the years about each type of UHF antenna, in very brief form. Today's consumer-grade UHF antennas, needed for receiving the great majority of DTV stations OTA in Canada, are divided into two basic designs:
Corner Reflector Yagi (pronounced yoggy)
Both have their relative strengths and purposes. The three main antenna manufacturers in the Canadian consumer marketplace (Delhi, Channel Master, and Winegard) make variations on those designs. There were Parabolic models available to consumers many years ago, but that category is now exclusively used by professionals, such as in CATV Head End scenarios or in research.
Corner Reflector YagisIf you have a clear, direct, unobstructed, line-of-sight aim from your antenna mast to the transmitting antenna and it is within about 80km of it, consider purchasing a corner reflector yagi like a Delhi CYD1470, Channel Master 4248, Televes DAT-75, Winegard PR-9032, or Antennas Direct 91XG (the best of this breed). It is very easy to aim because you can point it like a rifle at the broadcasting site and lock it into place. On a rotor swinging around to several different azimuths it loses out to the other type of antenna because it is so directional (biased in one specific direction) with a fairly narrow receiving aperture and relatively small side lobes, therefore can be quite picky to aim. This is actually a positive feature of the Corner Reflector Yagi because in known areas of signal crowding its great side-rear rejection qualities are needed. Some users do well with long distance reception using a preamp and a fixed mount. Some users do fine with a Yagi on a rotor, but in almost all such rotating situations it is bettered by the other antenna type.Bowtie ReflectorsIf some obstructions such as large trees lay between your antenna, or the broadcast site is more than about 80 km away, or if the stations are at several different azimuths and you want to put an antenna up on a rotor, you require a bowtie reflector such as a Winegard PR-8800, Terrestrial Digital DB-8, or the original Channel Master 4228 (the best of this breed). It's reflector mesh is great at gathering UHF signals that tend to scatter over long distances. Its receiving aperture is very wide and its side lobes are relatively large, meaning that on a rotor it will generally tend to get a digital lock on a DTV station before the Yagis above will. Having said that, it is also fine in suburban situations and in fixed positions for all-purpose situations. Each bowtie (x-shaped signal receptor) is known as a bay, and the greater the range to the station, the greater the number of bays should be. Four-bay versions exist for suburban to fringe use, such as the Delhi 4BT-1483, the Winegard PR-4400, and the new Channel Master 4221HD (the best of this breed). Some bowtie antennas such as the Delhi SL-4BT are sold without reflectors, giving a figure-eight reception pattern to those who are located in between desired stations. The chief difference between a CM4228 and a CM4221HD is that the CM4228 is more directional and provides about 3dB more gain, while the CM4221 has a wider reception pattern.
UPDATE Oct. 31, 2008: Channel Master has stopped making antennas in the USA and moved manufacturing duties to China. They have substantially changed (through outsourcing) all their antenna designs in the process.
UPDATE Jan. 27, 2009: OTA gear suppliers in Canada have run out of stock of the original-style Channel Master 4221s and 4228s. Additionally, testing reveals that the new CM4228HD antennas are weaker in performance than the original CM4228 models. It is advised that if an original CM4228 cannot be purchased, the reader should consider purchasing the next best model shown on the Antenna Chart.
UPDATE Mar. 16, 2009: Ken Nist, of HDTVPrimer.com, has published an easy hardware hack that corrects a significant flaw in the design of the new CM4228HD antenna, improving its performance significantly. Read about it in this thread (http://www.digitalhome.ca/forum/showthread.php?t=103749).
UPDATE May 1, 2009: A thread discusses hardware hacks that consumers can make to improve the performance of their CM4221HD (http://www.digitalhome.ca/forum/showthread.php?t=104837) antenna.Money Is No ObjectIf you must, and absolutely MUST, have the ultimate in UHF antenna performance, you can buy precision cut single channel or log periodic antennas from professional-grade manufacturers such as Wade or Blonder Tongue, or you can contact Wade about their colossal CATV head end parabolic models. If you think you need one of these bad boys (especially the dual dish model) parked up on your roof, go see a psychiatrist but definitely check your local bylaws and ordinances before you drain thousands of $$$ from your bank account!
2005-12-11, 02:52 PM
Let's face it, for Canadian consumers the choice of TV antennas usually comes down to a short list of four main brands that give the best performance for the money and especially in Canada's wide geographic areas and cold, cold winters/hot, hot summers.
On another web site I read a commentary in which a consumer said something like:...the price of the [name of manufacturer]'s antenna was higher so I assumed it was better than [name of other manufacturer]'s antenna, but it wasn't.Please, please don't fall for the price = quality myth. I also read about a person who custom ordered an antenna from Europe at high cost, only to find out that its performance was not much different from a much cheaper main brand. By all means check the technical specifications of antennas, but also ask here in the DHC OTA Forum about performance in the real world, which is where it really matters. We also give second opinions here, in case you've gotten advice elsewhere.
My personal opinion is that for almost any customary consumer usage in Canada I would be very surprised if you cannot find a satisfactory antenna from one of the four main manufacturers. Most of the TV antenna professionals and experienced hobbyists in Canada have personal experience with them and can easily get parts and accessories for them. Buying from Canadian suppliers is also good for our small business economy too. ;)
This section of the OTA FAQ intentionally omits a great number of cheap "clone" brands of antenna that are almost always poorly designed and weakly constructed. If you have bought an antenna in Canada and it's brand name is not listed here you have unfortunately bought a lousy antenna.
Main Consumer Grade Antenna Brands in Canada
Manufacturer - U.S.A - Consumer antennas - wide product line
Manufacturer - U.S.A - Consumer antennas
Manufacturing and Marketing -U.S.A. - wide product line of it's own and rebranded antennas
http://www.antennacraft.net/ and sold in stores by: The Source: Canadian retail electronics chain - rebranded Antennacraft and international antennas
http://www.thesourcecc.com (http://www.thesourcecc.com/estore/category.aspx?language=en-CA&catalog=Online&category=Outdoor+Antennas&pagenum=1&sort=1) (see Home > TV & Home Entertainment > Antennas > Outdoor Antennas on web page) Radio Shack: U.S. retail electronics chain - rebranded Antennacraft and international antennas
http://www.radioshack.com (http://www.radioshack.com/) (see Home Entertainment -> Accessories -> Antennas on web page)
Channel Master (original pre-2008 stock only - see International section below for post-2008 info)
Manufacturer - USA - Consumer antennas - wide product line
Important Channel Master News August 19, 2008
I finally got to talk to Ron Morgan at Channel Master engineering regarding the replacement 4228HD.
1. CM just closed their manufacturing plant in the US last week!
2. All the new antennas are made in (guess where) China.
3. They are even farming out testing the new design to another testing facility (no specs yet).
4. They should be shipping them in November.
5. The weight of the new design is around 10 lbs (3 lbs less than the orginal).
6. The horizontal elements of the reflector are solid.
7. It comes assembled, but you have to extend the "bow tie" brackets out from the reflector. The shipping box is around 3" thick.
8. They are attaching a warning sticker on the matching network not to overtighten the F fitting. It seems they have had problems with their preamps with overtightened fittings. (the same goes with Antennas Direct)
9. The matching network is NOT replaceable (see above).
My high regard for Channel Master just went in the toilet.
(The engineer wasn't happy about the closing either stating how long Channel Master has been in business in the US)
Better get the orginal design while you can.
Manufacturing and Marketing - U.S.A. - sells own and rebranded antennas through stores - range of different types including gimmick antennas - some rebranded as Magnavox, some as Zenith
http://www.gemini-usa.com/gemini/pro...r%20Antenna s (http://www.gemini-usa.com/gemini/products.asp?Ctg=Antennas&SubCtg=Outdoor%20Antennas)
Manufacturing and Marketing - U.S.A. - sells own and rebranded antennas through stores - range of different types - still living down bad reputation from certain gimmick antenna products - have teamed with Winegard to improve Terk's product quality
Manufacturer - Canada - made by Wade Antenna and includes Delhi and former Jerrold consumer brands - after 2010 has left the consumer antenna business - was leader in consumer VHF/FM and VHF/FM/UHF Combination antennas
Professional, CATV, Military, and Research (Highest Quality)
Wade's professional division (TACO), along with Blonder Tongue, cater to the highest end of the professional OTA market, in which CATV Head End installations and Research are the main usage. Products like precision cut single channel yagis, log periodic antennas, and giant parabolic reflectors are therefore built to exacting standards and in fact are often not useful to average consumers wanting basic UHF/VHF/FM antennas due to their specific designs for only certain uses. It is possible to find useful consumer-grade antennas from them, but they'll be very expensive. Each manufacturer offers a wide range of professional grade OTA antennas, amps, and related OTA gear.
Wade Antenna (TACO brand & former Lindsay products)
Manufacturer - Canada
Manufacturer - U.S.A.
Manufacturer - Germany
Reputable Internationally-Manufactured Consumer Antennas
Keep in mind that due to smaller broadcast areas across Europe and Asia, the antenna manufacturers give less emphasis to the kind of fringe and deep fringe conditions that we take for granted in North America, but more emphasis on side and rear signal rejection due to greater competing station density over there. Certain UHF antennas from Europe and Asia are unusable here due to some frequency differences. VHF antennas from Europe are not suitable for Canada, usually due to polarity differences.
Channel Master (post-2008 stock only)
Manufacturer - China - Consumer antennas
Blake - UK
Manufacturer - consumer antennas - solid construction and build quality
Televes - Spain
Manufacturer - consumer antennas - products are very distinctively designed and coloured - UHF corner reflector yagis
Kathrein-Scala - Germany
Manufacturer - consumer antennas - rare in Canada - highly regarded in Europe
Triax - Denmark
Manufacturer - consumer antennas - rare in Canada
2005-12-11, 09:47 PM
In the passing age of Analogue TV reception, indoor antennas have suffered a myriad of reception problems, and more money has probably been wasted on them over the years than on any other type of OTA equipment. In fact, the Consumer Electronics Association, which provides general ratings of all standard antennas, continues to refuse to rate indoor antennas.
The transition to Digital TV is helping to overcome many of the reception difficulties faced by indoor antennas, but not all such problems can be easily cured. For this reason, they should be considered last or only if an outdoor antenna is not a possibility.
Zenith Silver Sensor & Clones
The Zenith ZHDTV1Z Silver Sensor indoor antenna is considered the benchmark design for indoor UHF ATSC antennas.
Other manufacturers build clones under their own brand names, such as Terk, Philips, Samsung, and others. Its distinctive flying-vee style is instantly recognizable. Consumers will find occasional differences in some ZSS clone brands, such as a single, non-sectional element cover and/or the addition of extendable rabbit-ear elements for added VHF reception and/or an integrated signal amplifier.
Generally a consumer can feel comfortable that a ZSS clone will perform almost identically to the original ZSS.One correction on the Indoor antenna section. Zenith did not design the Silver Sensor. It was developed by Antiference in the UK as the SS100 for Digital TV over there. I,and a few others purchased them through a Mom & Pop importer here in the States sometime around 2001-2002. Wish I still had one for old times sake. Not sure how the connection with Zenith was made, but I do know they were overwhelmed with orders and were looking for a US company to license the antenna and extend the production away from the UK.The following discussion thread deals specifically with ZSS and ZSS-clone antennas:
I have to use an indoor antenna and I only get VHF stations. Which kind of indoor antenna will work?If your intended stations are all on VHF and you will not be getting any UHF stations, a set of good old fashioned rabbit ears is okay for your situation since you cannot use an outdoor antenna. Just remember that conventional rabbit ears are not suitable for UHF reception. Don't spend a lot of money on rabbit ears - the cheapest basic unamplified ones from Zellers or WalMart are fine - don't read the claims on the boxes when you are shopping!
You will need to put the aerials completely flat horizontally from the centre stand, not upwards or in a Vee. The lower the channel number, the more you need to extend them outwards. The higher the channel, the more you need to push them in. Practice makes perfect.
Further, you will need to rotate the rabbit ears to get the intended stations, depending on which direction the signals are coming from. The aerials have to be at a right angle to the direction of the signals.
If this doesn't work out for you, try an amplified set of rabbit ears, but keep in mind that amplifying indoor TV signals actually amplifies ambient signal noise too so your results will vary.
Antennas Mounted In Attics
Analogue TV reception with attic-mounted antennas has traditionally been haphazard and unsatisfactory for most people due to problems with ghosting and other interference caused by reflection of signals off of metal hardware such as sheet metal flashing, electrical boxes, aluminum siding, etc.
Digital television had similar problems in attics during the first few generations of ATSC tuner, but the situation has been greatly improved with the Generation 5 and newer chipsets now on the market. The problems have not disappeared... they've just been addressed a bit better electronically.
Having said that, of course an indoor and/or attic antenna is generally no match for a proper outdoor antenna in almost any situation, so an attic mount should always be considered last after exhausting all outdoor antenna mounting possibilities.
2005-12-11, 09:47 PM
First a little bit of electronics theory to clarify some conceptsHopefully this will not leave you glassy-eyed or confused, so you can skip this part if you like and go right to the next post in the OTA Knowledge Base & FAQ. :)
TV signals travel in waves between the transmitter and your antenna(s), with the transmitter's waves causing the receiving antenna(s) to resonate in the same pattern
this is like having several tuning forks in a room close together - if you strike one (the transmitter) the identical tuning fork (the receiver) will resonate the same, just quieter
the harder you strike the transmitting fork the louder it will be and the louder the receiver fork will resonate or the farther the receiver fork can be to still resonate
the other bigger and smaller tuning forks will remain silent through it all and show no resonance because the transmitter waves do not affect them, no matter how powerful the transmission
TV signals are separated from eachother by their frequency, expressed in multiples of 1 Hertz. At a frequency of 1Hz a wave is replaced every second, which is why 1 Hertz used to be called 1 cps (cycle-per-second) in many parts of the world
the range of all frequencies is called the frequency spectrum
contiguous frequencies are grouped together on the spectrum in bands, such as the VHF or UHF TV bands or the FM Radio band (for a detalied list see the table in Post #20 of this FAQ)
the VHF and UHF TV bands are divided into channels (VHF-LO = Channels 2 through 6, VHF-HI = Channels 7 through 13, and UHF = Channels 14 through 69)
the FM Radio band does not have channels - stations are assigned frequencies expressed in MegaHertz from 88.1 MHz to 107.9 MHz TV antennas are commonly constructed for only a single band (UHF-only, VHF-LO, or VHF-HI)
a broadband TV antenna is one that is designed to pick up all channels in every TV band, sometimes with the FM Radio band too
the opposite of a broadband antenna is a channel cut model, which is optimized for just one specified channel
the lower the channel number on your TV, the lower the channel's frequency
the lower the channel's frequency, the longer its wavelength (frequency goes down while wavelength goes up, and frequency goes up while wavelength goes down)
the longer the channel's wavelength, the wider the receiving antenna's element must be to capture each wave
Channel 2 has a frequency of as low as 54 Megahertz with a wavelength of 5.55 metres (18.22 feet)
Channel 69 has a frequency of as high as 806 Megahertz with a wavelength of .37 metres (1.22 feet)
this is why VHF antennas are so much bigger than UHF ones
when TV stations wish to build an OTA transmitter they must calculate the power required to cover their desired geographical area
this area is called their contour
transmitter design is a highly technical feat of engineering and is overseen in Canada by federal government authorities (Industry Canada handles the technical details and issues, while the CRTC handles licensing details and issues)
the power that a TV station is authorized to transmit with is called their Effective Radiated Power (ERP)
thus, for example, under normal circumstances a TV in Fredericton cannot get an OTA station in Moncton because the ERP of the Moncton station is only sufficient to cover a locally specified contour
Why do some stations broadcast in the VHF band while others are in the UHF band?Usually a station's assigned channel is a matter of it being available in a given area so that it will not interfere with another station on the same channel in a different area. VHF channels were the original ones, but over the decades channels in the UHF band were assigned by Industry Canada (and the FCC in the U.S.A.) as demand for channels by broadcasters increased.
Broadcasters prefer the VHF-HI band due to the laws of physics and electromagnetism. VHF channels require much less transmitter power to cover the exact same area as UHF channels. For example, to cover a certain area, the higher the channel number, the more power it would take. Conversely, the lower the channel, the less power it would take to cover that same area.
Another factor is that VHF-HI signals tend to travel (propogate) better over a given area than UHF signals. Unfortunately in the case of VHF-LO channels the signals tend to suffer interference worse than VHF-HI and UHF channels. During the transition to digital TV across North America, the use of VHF-LO channels is being phased out and the frequencies reassigned to other uses than television.
How does a bowtie reflector antenna work?Why are the wires on the CM 4228 and CM 4221 at angles to the horizontal? I have been reading up on the fundamentals of antenna theory and one of the things that I learned is that the polarization of the transmitter and antenna must be the same in order to get the best signal reception. I have read that TV broadcasts use horizontal polarization.
My question now is why are the receiving wires (bow ties?) on these antennas in the V shape with angles away from the horizontal. Would it not be better if all the wires were horizontal - parallel to the ground?Hi Zozo,
You can't just look at a single wire, but have to take the resulting effect of the entire bowtie into account (in fact, all those bowties and the reflector affect each other greatly as far as electromagnetic field goes). The two-wire bowtie is actually a crude approximation of a cone-shaped solid conductor, which turns out to work over a wide frequency range compared to just a single wire. Engineers found out that by making them with just two wires instead was almost as effective, and much cheaper, less wind sensitive etc. In any event, the net effect is that it's horizontally polarized, and has a wide bandwidth. Just what you want for a TV antenna.
What does a reflector on an antenna do?Reflector meshes or rods cause an antenna to be "directional" by causing signal strength from behind to be lessened while simultaneously causing the gain at the front of the antenna to increase by the same amount. The reception pattern thus becomes very forward-biased, which is rated as its Front-to-Back ratio (FB). The higher the FB, the more directional the antenna is.
On the other hand, a reflectorless antenna has a figure-eight reception pattern with an equal FB.
2005-12-19, 04:44 PM
Do you have a diagram of how Digital OTA works so that I can print it out to explain it to my friends?This illustration gives an overview of the Digital OTA broadcast process from a TV station's cameraman all the way to a typical full OTA home installation with outdoor antenna (skipping tons of technical detail, of course!):
So, will I need all this OTA gear shown in the diagram?Maybe, maybe not, (See Post #2 in the OTA Forum Knowledge Base & FAQ) but the best way to find out is to read through the Reception Results thread for your area to see how others have done. :)
2006-01-10, 01:55 PM
I go way back with Over The Air (OTA) television. When I was a kid my dad was doing TV and Antenna repair/service in the 1950s as a moonlight job while he was an avionics guy in the Royal Canadian Air Force so I grew up all across Canada as Dad got transferred around. Then through the '60s and 70s he worked in educational television program production in Ontario. I worked with my dad in the TV program production world and doing CATV installations in schools and large buildings.
OTA is a hobby of mine that had gone away until the promise of ATSC DTV (Digital Television) brought things right back to life again in the late 1990s. When I joined the Digital Home web site, finding folks there who shared my OTA interest was a bit difficult although there certainly were very knowledgeable OTA folks, but besides them I was struck with how few people seemed to understand the past, present, and future of OTA. I had been lurking in several U.S. OTA forums and had been actively posting at Home Theater Spot's Antenna Spot for awhile, where I got to know quite a bit about today's ATSC environment as it was unfolding in the U.S. a few years ahead of the Canadian OTA scene. I realized that much of what was known about analog OTA was applicable to digital OTA too, but there are some rather key differences.
Hugh, the Digital Home site owner, was very supportive and helpful about starting a forum here specializing in OTA, and so it is my pleasure to have created and moderated the Digital Home Canada OTA Forum to share such info. It is my hobby, and so you will find a spirit of friendly good-fellowship there.
We get some veteran OTA professionals and hobbyists there who chip in and offer their expertise, and some of them have been posting at Digital Home for several years. Overwhelmingly, though, the visitors are newcomers to OTA and generally too young to remember when antennas were a necessity and cable (and especially satellite) TV were really new or unheard of.
Thus, my philosophy regarding the OTA Forum is that it is a Knowledge Base, so that people setting up or adjusting their gear for the first time or the fiftieth time can have some of the guesswork reduced or eliminated no matter what level of knowledge the reader arrives with. I delight in reading the first results reports from newcomers, and it is pleasant when the more experienced readers offer advice and assistance to fix problems or address concerns. To me the advice must also come in the form of warnings, "gotchas", and other tips. We keep in mind that there are no stupid questions and no technical OTA issues too small to discuss. There is only one way to do things right, and that is to do them the right way. Cordially disagreeing with me is quite alright, by the way.
Here is my personal web page if you wish to find out a bit more about me: http://www.user.dccnet.com/jonleblanc/
Nice work stampeder. It's really nice when members take the time to help others.
On behalf of DHC and all members, thank-you!
2006-04-11, 01:56 PM
WARNING: If you have not already read Post #2 in the OTA FAQ please do so now. Even with the best prediction tools as listed below, your results may vary!
Using TVFool to Determine Your Available OTA Stations in Canada
Follow these step-by-step Instructions:
use Google Maps Canada (http://maps.google.ca) to zoom in to your location and get your exact Latitude and Longitude map coordinates
enter your exact map coordinates at the TVFool (http://www.tvfool.com/) site and wait for your results page to load
your coordinates and location will be kept secret - it will not show up to anyone else on your completed report
NOTE: Canadians are advised to NOT use their proper street address, city, province, or postal code due to inaccuracies - hopefully this will be resolved soon
after it loads, copy-and-paste the URL of your personal TVFool report to a file or clipboard for future reference
read through the Reception Results thread for your area to see how others have done, in case there are local reception issues
if you require assistance analyzing your TVFool results just post the URL you saved above into a post at this site
Using the Rabbit Ears site:Stumbled upon this site the other day: http://rabbitears.info/
Info seems to have the same FCC database errors as TVfool.com, but there is some Canadian data. Things I found neat:
the market map
the TVGOS serivce list
and the Max Contour Tool (I never would have thought that in the Buffalo market WNYB was champ!)
The contributors to Rabbit Ears are mostly folks from one of the big U.S. online OTA forums.Using SJM's site:I've built a visual application that integrates tv transmitter data with Google Maps. I've plugged in co-ordinates, distance and bearing as well as showing the channels that are broadcast from each transmitter.
At the moment I have only loaded in Ontario and New York state data but would welcome any feedback as to the usefulness of the application. If people think it's a good idea I'll gladly spend more time in polishing it and rolling out more data.
http://www.sjmillerconsultants.com/ota/Using the FCC's Online Mapping Engine:You can go to the FCC's OTA maps site and punch in your Canadian postal code to see if any U.S. stations will reach your area. When it shows the stations you can click on one to see a direct line from your location to it: http://www.fcc.gov/mb/engineering/maps/Using Google Earth and/or Google Maps:
Part of my planning is figuring out which way to point my antenna. I figured if I got lucky I could go with a roof mount which wouldnt be visible from the front of my house.
One major question was: which way did I have to point the antenna. I wrestled with the math for a while and then I found this site:
Using google earth, I wrote down the coordinates of my house in Milton to Toronto (43 38 51.27N 79 22 49.49W, and Buffalo (42 53 13.34N 78 52 48.57W) I copied the numbers into the above site and found that it is 54 KM and a bearing of 76 Degrees 04' 55" to Toronto and 117.58 km and 127 degree 10' 15" to Buffalo.You can also use Google.ca to get TVFool resuts:
go to http://maps.google.ca
center the map on your house
click on the link button
copy the link to the clipboard
go to http://www.tvfool.com/index.php?opti...pper&Itemid=29
click on the coordinates button
paste in your coordinates from maps.google ca and it will produce a report of all the local tv stations.
Armed with my compass, I should be able to site the antenna and, when necessary, align the antenna(s) to the above bearings. That's a great starting point. With most ATSC tuners you should have a signal strength or signal quality meter that will let you take the final setup step of "peaking" your antenna for its specific best performance. Make sure to do that with all the expected channels in that direction so that you can come up with the best compromise among them. I've seen signal strength change with even just a tiny twist of the mast, so taking this step is definitely worth it.
One more thing: if you're using 2 or more antennas don't be surprised if your common logic about aiming goes awry as their reception lobes superimpose and interact. You might discover like some other DHCers have that some really weird effects happen, with resulting aiming that is counter-intuitive. It doesn't always turn out too radical, but ya never know...
An easier method (though not as refined) is to use the Measure tool in Google Earth:
1. Draw a line between your antenna and the transmitter using the measure tool.
2. The line will pass through landmarks along the sight line to the transmitter.
3. Aim the antenna at a landmark you can see / recognize.
No compass, no measuring, no calculations
In my case I aimed my silver sensor at Grand Island, NY and I can pick up a couple of Buffalo stations as long as the weather's not too bad.
I've done a Google Earth mashup of all present and future Vancouver, Victoria, Bellingham, and Seattle/Tacoma OTA TV stations as per the Industry Canada and FCC databases. It is really cool to zoom in on the Mt. Seymour antenna farm or the multi-tower installations in Seattle and Tacoma. :)
If you don't have Google Earth, you can download it for free for Windows, OS X, and Linux from here: http://earth.google.com/
Download my mashup file (Save To Disk): http://www.user.dccnet.com/jonleblanc/Canada_TV_Stations/Van-Vic-SeaTac-OTA.kmz
Start Google Earth and make sure you have it installed and properly running
In the File Menu select Open and select the downloaded file to begin.
If you have any difficulties with Google Earth you can read through their help page here: http://earth.google.com/support/?hl=en
I might do some other Canadian areas, but if someone follows my format as a template and does a mashup of their own area of Canada, please post a link to your mashup file here and we'll see if we can get a good collection going. Note that this is not done with Google Maps, it is done with Google Earth.
Here is a screen capture of it from a fairly high altitude:
Here is a mashup of the OTA TV Stations available in Eastern Ontario/Western Quebec.
Here is a screen capture of it:
Here's one for the folks in Winnipeg, S. MB, and SE SK (don't expect these stations to necessarily be available without Deepest Fringe gear in many places outside of Winnipeg):
OTA Stations in the Sault Ste. Marie Ontario and Michigan area:
OTA Stations In Calgary, Alberta (created by DHC members gsjacobs (http://www.digitalhome.ca/forum/member.php?u=17692) and csclgry (http://www.digitalhome.ca/forum/member.php?u=60384))
Using the Antennapoint site:Antennapoint provides a quick set of aiming points for U.S. DTV stations nearest you:
http://www.antennapoint.com/Using the Earth Tools site:...this height thing.....you piqued my curiousity to find out how many feet above sea level. I found it here:
http://www.earthtools.org/Using the Touratel site:There are topological maps online here:
http://www.touratel.com/Determining Your Magnetic Declination in Canada: Don't trust compass bearings until you've factored in the magnetic declination for your location:
2006-04-18, 11:43 PM
Our Antenna Research & Development sub-forum contains a wide variety of discussions on almost every aspect of building a TV antenna. The following threads are found in that forum:
Best Home Brew, Do It Yourself OTA Antennas:Very High Performance, may be complex to build, may require some shop skills:
Introduction to the Gray-Hoverman TV Antenna (http://www.digitalhome.ca/forum/showthread.php?t=81982) (UHF, some variants have VHF-HI capability)
Bow Tie TV Antenna Designs (mclapp's M4 featured) (http://www.digitalhome.ca/forum/showthread.php?t=100137) (UHF, some variants have VHF-HI capability)
400-A "Finclone" - Huge & Powerful (http://www.digitalhome.ca/forum/showthread.php?t=100838) (a real chore to build, great VHF and UHF capability)
Delhi 5y & 10y Channel Cut VHF Yagis - Saved From Oblivion For DIYers (http://www.digitalhome.ca/forum/showthread.php?t=139654) (VHF-LO or VHF-HI capability on specific channels)
Good Performance, less complex to build, suitable for hobbyists and inexperienced:
Building The Stealth Hawk TV Antenna (See Post #304) (http://www.digitalhome.ca/forum/showthread.php?t=123803)
Building The Centipede TV Antenna (http://www.digitalhome.ca/forum/showthread.php?t=120479)
Less powerful but convenient, easy to build:
The "Hentenna" Compact TV Antenna for OTA (http://www.digitalhome.ca/forum/showthread.php?t=104305)
The Bi-Quad Indoor TV Antenna (http://www.digitalhome.ca/forum/showthread.php?t=124542) (suitable for highrise buildings)
UHF Loops - simple bi-directional antennas (See Post #109) (http://www.digitalhome.ca/forum/showthread.php?t=135981)
What NOT To Build:Before wasting your time or ours on an antenna that you saw in a video or found on a website please read these threads:
OTA Clone, Coat Hanger, and Junk Antennas (http://www.digitalhome.ca/forum/showthread.php?t=106108)
Wacky, Tacky OTA Gear (What NOT To Buy!) (http://www.digitalhome.ca/forum/showthread.php?t=35083)
Antenna Research & Development:For those of you wanting to take part in leading edge technical design, computer modeling, building, research and development of antennas at our site:
4nec2 & Other Antenna Design Modeling Software (http://www.digitalhome.ca/forum/showthread.php?t=83772)
Area 51 for Antenna Modelers & Builders (http://www.digitalhome.ca/forum/showthread.php?t=105660) (Be sure to read Post #1!)
Fractal TV Antenna Research & Development (http://www.digitalhome.ca/forum/showthread.php?t=95684)
Tips & Tricks For Antenna Construction:See these threads for invaluable tips and tricks on how to build the very best DIY antennas:
Best Metals for Antennas: Performance, Soldering, Welding, Bending, Working (http://www.digitalhome.ca/forum/showthread.php?t=102202)
ABS, PVC, other plastics and Rubber for structural parts (http://www.digitalhome.ca/forum/showthread.php?t=96673&highlight=plastics)
Wire Straightening/Bending Tricks For Antenna Builds (http://www.digitalhome.ca/forum/showthread.php?t=100636)
Wood as an Antenna Material? (http://www.digitalhome.ca/forum/showthread.php?t=129560)
Finding Antenna-Build Parts in Canada (http://www.digitalhome.ca/forum/showthread.php?t=102248)
2006-04-19, 02:42 PM
I'd like to ask for a any advice or insight about legal issues related to OTA reception from the antenna installer's perspective. I want to make sure that by installing antenna(s) to a client, I'm not exposing:
a. my client
b. myself as a service provider
to legal consequences caused by eliminating the fees (or any other duties), that would otherwise hypothetically flow from the cable or satellite provider towards an individual broadcaster on behalf of the individual subscriber. By this fees I mean copyrights, program licenses, etc. I don't know if such fees and flows do exist or not, just want to make sure I'm legally clear.
I was trying to get an answer to this question talking to CAB or CRTC, but no one is willing to provide me with any binding statement.
I myself have a couple of other "underlying" questions such as, who is the owner of the individual transmitters? A broadcaster? Are this transmitters available for the public or are they part of the infrastructure to help distributing the signal? How can broadcaster measure how much audience they reached through OTA transmission in order to quantify airtime price for advertizing? What would motivate a broadcaster to invest their money into OTA transmition when potential reach is (for now) so tiny?OTA is free to receive...
You are not stealing... these are public broadcasts... just like listening to FM in your car.
By broadcasting OTA, this establishes a TV channels local region which defines what area it has advertising rights to simsub over on Cable.
TV broadcasting in Canada has been done Over The Air since the 1950s. Cable and Satellite came along later as supersets of that. OTA is 100% legal and always has been.
By installing antennas for clients you are not exposing yourself or your clients to any legal consequences arising from their receiving Digital OTA TV. Antenna installers have been doing it for almost 60 years in Canada and it is completely safe from a legal perspective regarding their clients' reception of broadcasts.There are other aspects to consider...
1. Who in fact owns the property where the antenna is to be located
2. Local bylaws regarding such installations
3. MATV setups as discussed in this thread and others:http://www.digitalhome.ca/forum/showthread.php?t=57242&highlight=antenna+condoOkay, to sum up: In terms of bylaws, ownership issues, etc., this can be handled by a disclaimer transferring responsibility on the client.In my own municipality of Delta, British Columbia, Canada, a home owner can erect a self-supporting TV antenna tower without the need for a permit provided that no part of the tower, including its guy wires, may touch a building or structure on the property. If the tower is to be bracketed to a roof joist or if a guy wire is to be anchored on the home, garage, deck, or other structure on the property a building permit must be obtained.
For further reading, please see this excellent thread: OTA - Local By-Laws, Legal & Regulatory Aspects (http://www.digitalhome.ca/forum/showthread.php?t=85247)
2006-04-19, 02:43 PM
OverviewIn a perfect OTA world, a consumer would just connect a small antenna to their HDTV and proceed to pick up all the wonderful DTV programming available in their area. In reality there may be cases in which the OTA gear needs to be of a certain quality and performance capability to bring in distant or dispersed signals. Boosting the antenna's output is often the answer, so preamplifiers and signal amplifiers are commonly available for OTA users to accomplish that task.
Not all OTA amplifiers are alike. Each type of amplifier has a separate role to play, so they should not be confused with each other. The amount of energy coming off of an OTA antenna is quite small compared to the energy coming out of a cable TV connection or a VCR, as an example. With the amount of energy from an antenna being so small, we need the amplification to deliver as pure a signal as possible. Unfortunately all amplifiers add "noise", which is the enemy of good reception.
A preamp is therefore specially designed to boost that OTA signal but with only a very little bit of noise added. By contrast, a signal amp, distribution amp or drop amp is fundamentally noisier, because the incoming cable TV signal is strong enough to get around the noise problems. Amplifier designers have a lot more leeway with the design of them versus preamps, so they are not as "clean". When looking at the specifications of any TV amplifier it is important to look first at it's "noise figure" (expressed in dB) instead of it's advertised boost.I've walked in your shoes, trying a million different set-ups, and constantly learning. My biggest lesson was realizing that amplification is a two edge sword.In some cases the signal from the antenna might be too strong, so there are ways to lower that signal while keeping the quality of the signal high.Key Concepts:
Amplification = Boosting or increasing the OTA signal
Attenuation = Reducing or lowering the OTA Signal
Noise = unwanted "junk" added to the OTA signal that can sometimes prevent tuners from acquiring a digital lock on a DTV station
OTA Amplifiers - A Quick Introduction
input = antenna signal
Output = very clean, boosted antenna signal
input = any unamplified OTA signal
Output = one boosted OTA signal but usually more noisy than a preamplifier
input = any unamplified OTA signal
Output = 2 or more with boosted signal but usually more noisy than a preamplifier
Drop amplifier: same as Signal amplifier but is really for CATV use due to extended frequency range past OTA frequencies
OTA Preamps - a Pleasure To ComparePreamps are used for taking in your antenna's signal as close as possible up the mast nearest the antenna and amplifying it in very specific ways to allow the signal to travel strongly down a cable to your tuner. Don't assume that any old TV/CATV amplifier will do, it has to be a specifically designed antenna preamp.
In many cases an antenna gives strong enough signal power on its own to drive the tuner so a preamp would not be necessary. In most cases, a weak signal in a fringe or deep fringe area can be dramatically improved with a preamp. In other cases, a mixture of near and far stations can cause preamp problems. For example, someone in downtown Toronto should ask before using one because of their proximity to the CN Tower's already strong signals. There are always ways around those problems using filters, blockers, attenuators, traps, etc.Another purpose for a preamplifier that is often overlooked is to compensate for a noisy first stage amplifier already in your TV. Back when most people used OTA, all TVs had low noise amplifiers to help receive weak signals, but now that most people have cable or satellite, many TVs have cheaper (noisy) first stage amplifiers. A preamp with enough gain will cause the Automatic Gain Control (AGC) circuit controlling the internal first stage amplifier to "turn off", and if your preamp isn't as noisy you will be able to receive weaker stations more easily.Not all preamps are alike, even from the same manufacturer. Some have higher amounts of added "noise", others lower. Noise is the enemy of TV tuners, so the lower the better. Some provide low amounts of "gain" (boost), others are for very high gain. Don't assume that the preamp with the highest gain figure is necessarily the best for all conditions. Bad idea.
Due to the very critical role that OTA Preamps play, the manufacturers almost always provide reliable specifications for those products. People have been using Preamps for decades, so their Gain, Noise, Loss, and other properties are well known. It is possible to make direct comparisons between them, so in our case we have the charts and tables in the OTA Forum that clear up any questions. When a new type of Preamp like the models from Kitztech and Research Comms come along that clearly outperforms the others, that's big news and you'll read about it here!Professonal Signal Amplifiers, Drop Amplifiers, and Distribution Amplifiers - Reliable and Known PerformanceIf a preamplifier is not sufficient to provide a strong enough signal to all your TVs, FM radio tuners, PVRs, and other receivers below the antenna, it is time to put in an amplifier below the preamplifier. Having said that, there are times and places in which a very high gain/low noise preamplifier can do the job itself, but seldom the other way around. A signal amplifier is not therefore a lesser thing than a preamplifier; it has 2 benefits: some models can be purchased with several outputs, some with adjustable input and outputs, and in all signal amplifiers are generally capable of handling high power input signals and spreading them evenly across one or more outputs. Other more specialized signal amplifiers allow blending of such things as the OTA signal with CATV, Satellite, etc.
High performance Signal Amplifiers, Drop Amplifiers, and Distribution Amplifiers (especially for MATV systems) are offered for sale by well known and reputable companies like Blonder Tongue, Tin Lee, and others, and from the big antenna manufacturers like Winegard and PCT (the new Channel Master) too. The specs are published, the performance attributes are well known, and the results are predictable. These are the preferred choice of OTA professionals and hobbyists, and they understandably carry a price tag that may seem out of reach for some consumers. The Sorry State of Common, Store-Bought Signal AmplifiersNow contrast that with the sorry state of Signal and Drop amplifiers that are sold blister-packed, far and wide, in consumer electronics and department stores. Apart from their Raw Gain figures, none of the critical specifications such as Noise, Return Loss, and others are listed on the packaging nor even on the web sites of the companies shown on the labels. Indeed, it is often impossible to tell whether any company electronics engineer would exist to answer questions about those specs. :mad: Most likely the amp was imported and relabeled for our marketplace. So, while it might be tempting to simply add "12.5dB of boost" to your OTA system as the packaging material might say, you might also be adding unacceptable noise and/or other properties that cripple reception.
I completely understand that some of you are hoping for a comparison chart or objective test evaluation of commonly available signal amps discussed above, and I would absolutely welcome any such test results posted here by someone with electronics testing experience, but at some point the consumer has to acknowledge that the entire category of them is suspect. As with any product, some people have good luck with them, but I personally have avoided them since the 1980s when the better ones started to disappear from the marketplace.AttenuatorsIf your chosen amplifier's output is too high, causing trouble with TV reception, it is possible to either adjust a distribution amp's output level downwards on some models or put an attenuator downstream of the amp. Attenuators are for purposely lowering the signal strength in a cable run in order to prevent such symptoms as signal overload, in which a TV or FM Radio tuner cannot cope with too strong a signal. Its not good to try to fill a balloon with a fire hose... ;)http://www.digitalhome.ca/forum/picture.php?albumid=260&pictureid=9186You can get them in a wide variety of attenuation levels from a good antenna store, but I also found them in 6db strength (only) at The Source for a low price, where they are sold under the Nexxtech brand. They look like simple F-type coax couplers, but a little bit longer. They are handy to have around if you are trying out a new preamp/amp. Adjustable attenuators are also avaliable but are more expensive. Reasonably priced adjustable attenuators can be found on the Antennas Direct website.
Important note: If you have a preamp and you are putting the attenuator in its direct path you need to make sure that your attenuator does not block DC current from the preamp's power supply or the preamp will not have power to operate.FiltersSometimes there are cases in which we might wish to raise or lower the signal on an entire band, such as when joining two antennas to use the UHF band from both of them but using only the VHF band from one of them. Perhaps we might wish to just raise or lower the signal on specific channels in relation to the other channels, rather than on all of them. For this we use filters. Filters cannot amplify; they only attenuate.
Filters work the same on the VHF, UHF, and FM Radio bands.
If we're filtering an entire band the device is known as either a Band Pass or a Band Stop filter.
Band Stop filters are often named as Traps for the affected band, such as an FM Trap filter on a preamp.
Some filter devices have variable filtering levels for stopping/trapping certain channels or likewise passing them.
If we're filtering just certain channels instead of entire bands the device is known as a Notch filter (they get the name "Notch" from the diagram of their operation).
Some notch filters block or pass just one channel, while some do several at once.
Some notch filters allow you to select the channels yourself, while others have to be purchased with the filtered channels preconfigured.
a Stop or Trap, which allows all channels through except for the one(s) that you want blocked (you'd ask for a "Channel 12 stop filter" or a "Channel 12 trap")Allowing all, but stopping/trapping 4, 7, and 9:
2 3 4 5 6 7 8 9 10 11 12 13
______ ______ ___ ___________
[-] [-] [-]
a Pass, which stops/traps all channels except for the one(s) you want allowed (you'd ask for a "Channel 33 pass filter")Stopping/Trapping all, but allowing 2, 5, 8, and 12:
2 3 4 5 6 7 8 9 10 11 12 13
2006-05-24, 01:07 PM
In layman's terms:
a Canadian Over The Air Digital Television station is given a specific channel n to play with by Industry Canada (channel 23, for example)
the old analogue system could use that channel for one station only
the new Digital TV system allows a station to carve up that channel's bandwidth (alotted space) in a variety of ways
how that station divides up that bandwidth is up to them (NOTE: the CRTC has never given an opinion on whether ATSC subchannels will be used in Canada - only a small number of stations actually use the feature but it is very common in the U.S.A.)
High Definition signals require huge amounts of that channel's bandwidth compared to Standard Definition signals because they are so much more complex
using data compression over and above the standard ATSC MPEG2 compression, a station can squeeze down the size of an HD signal but at a cost in picture and audio quality - the more compression, the worse the HD signal
maybe the station will throw all their energy into just one HD feed (without additional compression) in order to provide the best quality picture and sound (just channel 23.1, for example)
such a signal would show up on a consumer's ATSC tuner as channel n.1 (some ATSC tuners use dashes instead of dots) because it is the one and only subchannel being used (for example, 23.1)
maybe they'll decide to compress the HD signal to allow space in their bandwidth to allow 2 or more subchannels operating at a much lower quality, such as in SD or in other data types
in such a case the HD signal might show up as subchannel n-1, an SD signal as subchannel n-2, and another SD signal as subchannel n-3
the sub-channel(s) will have the exact same signal levels as the main channel since they're part of the same data stream being broadcast
maybe they'll decide not to broadcast in HD at all, dividing up their bandwidth into several SD and data subchannels instead
it is up to the station's management on what they decide to apply to the CRTC for in order to cover their broadcast area
Canadian consumers can intervene in CRTC application proceedings to either support or protest the plans of the stations to use their bandwidth for subchannels
U.S. stations use the same system of subchannels, as approved by the FCC
So, your ATSC tuner is the point at which a single OTA DTV channel might be split into a main and sub-channels if the broadcaster chooses.
Channel RemappingThis is a feature of the ATSC standard for use during the analogue-to-digital transition that allows broadcast stations to telecast on a newly assigned DTV channel but "trick" the receiver at your home into displaying a channel number that corresponds to the original analogue channel or any other unused channel they please.
For a fictional example:
An analogue station called CKZZ on channel 8 spent 39 years in a market and has branded itself heavily on its channel number. Their DTV assignment is channel 43 so they must move all their programming over to 43.1, but now they face a big advertising job and the loss of almost 4 decades of "Channel 8" market branding. Using PSIP Channel Remapping, CKZZ-DT begins telecasting on 43.1 but sets its PSIP data to display 8.1 on home receivers. Their "Channel 8" identity is thus saved. After the transition period is done (2009 in the U.S., 2011 in Canada) and the analogue Channel 8 transmitter is permanently shut down, CKZZ-DT's owners make the strategic decision to physically broadcast on 8.1 and leave 43.1 behind for Industry Canada and the CRTC to reassign to any other TV station they choose. Effect on the consumer? The home receiver picks up the change and adapts accordingly with no consumer effort needed. Once again, their "Channel 8" identity is thus saved. Everyone is happy.stampeder I don't understand what you meant here.
"CKZZ-DT's owners make the strategic decision to physically broadcast on 8.1 and leave 43.1 behind"
Are you saying that station wil broadcast on is 8.1(Vhf frequency), or set the psip id to 8.1 but broadcast on a UHF frequency ?
This would make more sense to broadcast on uhf and set the psisp to chan id 8-1. If not what will happend to those customers that currently has only a uhf antenna?DT stations will be allowed to reoccupy/replace their original old VHF analogue channel slots as long as they are in the high band (7 through 13) because VHF-low is being reassigned away from TV. In the example I gave, CKZZ analogue channel 8 goes dark one day, CKZZ-DT digital channel 43.1 (that remaps to 8.1) then shuts down momentarily, then comes back up genuinely on 8.1 and no longer on 43.1, which the authorities are now free to reassign to any other station that wants channel 43.1.
It is much, much more energy-efficient ($$$) to broadcast in the VHF-HI band than in the UHF band to cover the same area, so this is a desirable move for some stations to make. Others will decide to just stay where they are with their new assignments.
You can check the FCC database to see which stations in the U.S. near the Canadian border have elected to go back to VHF-HI and which have elected to stay in UHF. As always, the situation up here in Canada is murky at best.
This is why I will always keep an excellent VHF-HI antenna around... ;)
I understand how remapping works and in general don't have a problem with it. What I don't like is having a virtual channel the same as an actual channel in the same market.There ought to be rules against that, but unfortunately as a Canadian there isn't much you can do to ask the U.S. station(s) or the FCC to take action.
2006-07-08, 09:02 PM
Is there a way to combine two antennas to receive signals from two different locations?Absolutely, but ideally the antennas must be identical. Stacking identical antennas (such as two DB-8s) is relatively easy, and ganging different types of antenna that use the same band (such as a CM4221HD UHF with a 91XG UHF) can be quite difficult, while combining a VHF with a UHF is routinely done and works very well.
What is the difference between Ganging and Stacking two antennas?
"Ganging" is the combining of 2 or more antennas' outputs together into one coax or twinlead cable to provide signal to one or more TVs, including with physically separate, individually aimed antennas.The electronics term ganging is really just a re-use of the English word for:A combination of similar implements arranged so as, by acting together, to save time or labor; a set; as, a gang of saws, or of plows.In electronics I can have 2 resistors side by side on a circuit board but if they are involved in different circuits they are not ganged. If they are part of the same circuit and the current flows through both of them as part of the same task they are "ganged".
"Stacking" is the specific vertical ganging of 2 identical antennas faced in the exact same direction for long distance, deepest fringe reception. The goal of stacking is not to make 2 antennas into 1, but rather to get both of the antennas working as a team. For example, to stack 2 CM4221HDs, just mount one above the other in the exact same aim with their respective bowties spaced uniformly. By experimentation we can vary this spacing of the upper and lower antennas to find the best performance. Research shows that the 2 antennas can actually work against each other if spaced incorrectly. Stacking is a way of increasing the gain usually by about 2 or 3 dB over just the single antenna because the receiving patterns of the antennas join into one, and their focus is sharpened more to the horizontal than the vertical plane.
"Horizontal Stacking" is the same as above but with the antennas mounted side-by-side and aimed at the exact same azimuth, joined by equal lengths of coax or twinlead cable. Horizontal ganging is what Channel Master did perfectly in the 1980s with their original CM4228 antenna (ganging 2 original CM4221s side-by-side) and we can see this still in practice with such models as the CM4228HD and the Antennas Direct DB8. Unlike with pancakes, OTA terminology allows two objects to be "stacked" side-by-side. ;)
What are the basic rules of stacking and ganging antennas?
For stacking or ganging of co-mounted antennas aimed at the exact same azimuth (joined as a team) the coax/twinlead lengths must be exactly equal
For ganged antennas that are not stacked, proper antenna separation (see below) is vitally important
For ganging of antennas aimed at substantially different azimuths the leads can be of different lengths
For ganging of antennas in which the aiming points are less than 20° apart I still cut them identically
stacking or ganging non-identical antennas requires a great deal of trial-and-error for inconclusive benefit
stacking or ganging three or more antennas is best left to extremely dedicated experimenters
stacking or ganging indoor antennas with outdoor antennas is usually futile or extremely disappointing
no matter which method you choose, be prepared to test, test, test!
Ganging & Combining Antennas: A Walk Through
In a case where we have UHF stations in two relatively fixed directions that are between about 20 to 160 degrees apart we might be able to avoid using a rotor by ganging two antennas, but we will have some work to do. First, it is highly advised that the antennas be identical. It is possible to gang different brands or types of UHF antenna, but for the newcomer it can be overly complicated and difficult to accomplish.
For this article we will assume that Antenna A and Antenna B are identical CM4221HDs and that the path from each to their respective target stations is clear.
When we gang two antennas it is essential to use one of these two methods to connect them, with more detailed information provided later in this article:
connecting their feed points with 300 ohm twinlead (as short as possible) into a single balun, which then feeds into your preamp. If your antennas are subject to local interference use shielded, foam-filled 300 ohm twinlead.
connecting their feed points directly to individual baluns, which then feed over coaxial cable into a joining device to create a single coax lead going into your preamp. A high frequency, high quality 2-to-1 splitter will suffice as a joining device. Such splitters can be found in many electronics and satellite stores, but avoid the cheapie ones. The balun-to-splitter cable can be RG59 coax, but I personally use RG6 for everything just because it means buying one less coil of coax.
At this point, regardless of which option we choose, we might face a very basic electronic problem. We'll need to make sure that the two antennas are in phase so that their signals complement eachother instead of cancelling eachother out. We won't be able to tell if there is a phase problem until we hook up a TV or signal meter, so lets assume we're all hooked up and ready to test.
Now we face another very basic electronic problem. Ganged antennas cannot be too close together or their fields will interact in undesirable ways, so in the case of a CM4221HD we should leave at least 25 inches of space between them (see explanation later in this article). Remember that this minimum distance does not apply to stacking, just ganging.
At this point we need to take our best guess as to the aim of the two antennas, but don't worry yet about getting it right. We just need to have some signal showing up on the screen or on the meter. If there is little or no good signal after connecting the downleads of Antenna A and Antenna B through the splitter, disconnect the balun wires off of Antenna B, switch the two wires around, reconnect them to that antenna, check for signal, and we'll find that the signals are now in phase and are working properly together.
Next, we will have the actual aiming task to perform. The term for getting one antenna's aim perfect is called peaking. The most natural expectation is that we would disconnect Antenna A from the splitter and peak Antenna B perfectly for its intended station(s), then do the opposite to peak Antenna A for its own. Nope! If only it were that easy! ;)
Unfortunately there may be some further aiming to do. The problem is that antennas have a specific beam pattern of reception that has areas of strong and weak signal. For example, see this illustration of the CM4228's beam pattern (from the HDTV Primer site):
Now imagine if our two antennas, perfectly peaked individually for their own targets, share an overlap that causes a strong area (a peak) to overlap a very weak area (a null), and we can see that our reception will suffer. Of course the worst scenario would be if the two antennas shared nulls in the exact direction of some of our desired stations.
So, as we can see, a compromise is often required, and this best-of-both-worlds solution can take a fair amount of time and effort to locate exactly. Don't be discouraged. Many people have found aiming solutions that provide them with suitably strong reception from both directions of aim.
Stacking Identical Bowtie Reflector Antennas: A Walk Through
stack your antennas one above the other so that all of their bowties are equally, evenly spaced
combine their output with exactly equal lengths of RG6 into a reversed high quality splitter
run a single coax downlead from the reversed splitter
test by watching a signal meter on your TV or with a signal tester
if the reception is great your antennas are in phase and you can solder, twist, or crimp the twinlead ends to the balun and cover it with roofing tar or heavy duty electrical tape
if the antennas are out of phase your reception will be horrible
fix that by simply switching the two conductors on just one of the baluns
test again, slightly moving the lower antenna apart from the upper one to watch for improvements, and when you find the best solution go ahead and permanently attach all the connectors
And here's an experimental alternative to using a coax splitter when stacking identical antennas, but the problem is that the "rated" 300ohm impedence of each antenna (as broadband antennas their real world impedence is variable depending on the frequency of each channel) will combine to result in only 150ohms, which will cause a typical 4:1 balun to yield only 37.5ohm impedence on the coax downlead on some channels. This means that some channels may be weaker than the coax splitter technique while some may be stronger.
get about 8 to 10 feet of 300ohm twinlead (the old fashioned stuff)
connect both antennas with it, leaving about 2 inches of extra length
measure the length of that twinlead connection as exactly as possible
mark the exact middle of the length
cut and strip the 300ohm twinlead at that middle point
temporarily attach the balun to those twinlead ends (as the unison point of the output from both antennas)
connect your coax downlead to the balun
test by watching a signal meter on your TV or with a signal tester
if the reception is great your antennas are in phase and you can solder, twist, or crimp the twinlead ends to the balun and cover it with roofing tar or heavy duty electrical tape
if the antennas are out of phase your reception will be horrible
fix that by simply switching the two conductors on just one of the twin leads
test again, and it should be fine to permanently attach all the connectors
If I would like to gang two Delhi 10Y13s horizontally, could I use the same method with the 300 ohms twin leads?Yes, it would work exactly the same, so just be careful about testing if the antennas are in phase before you permanently connect them and the balun together. Also check the information below on correctly spacing your two Delhi 10Y13s.
Note to all about 300ohm twinlead
300ohm twinlead is usually fine for just about any ganging or stacking into a single balun, but if you are in an area that already is known to test badly for interference you should use shielded, foam filled 300ohm twinlead for more protection.
What if I want to use more than one antenna but don't want to combine them in any way?
If you want to use two or more antennas independently of each other, such as one for each apartment in a subdivided home, you will need to reduce or eliminate effects of the antennas caused by their proximity to each other. This issue is called Antenna Spacing. The antenna spacings given here have always served well :) but holl_ands has been doing some terrific research using computer modeling and can discuss it over in the Stacking, Ganging, Combining TV Antennas (http://www.digitalhome.ca/forum/showthread.php?t=95148) thread. The spacings here in the OTA FAQ are tried-and-true examples, while the results that holl_ands is getting are for people needing to get every last ounce of signal regardless of the complexity of putting up a longer/higher mast (wind and snow load, weight on a rotor, etc.) so please keep that in mind. To use the tried-and-true spacings listed here, first read Post #5 in the OTA Knowledge Base & FAQ (http://www.digitalhome.ca/forum/showpost.php?p=710401&postcount=5), then this:
Same-band antennas should be spaced apart at least one full wavelength (λ) of the lowest channel they can receive
use full wave spacing, but if not possible use half-wave (as a last resort try quarter-wave spacing)
VHF-LO (includes VHF/FM, VHF/FM/UHF Combo): channel 2 λ = 18.22 feet (5.55 metres) apart, but 1/2 can be done
VHF-HI (7-13) antennas: channel 7 λ = 5.65 feet (1.72 metres) apart, but 1/2 can be done
FM Radio antennas: 88MHz λ = 11.18 feet (3.41 metres) apart, but 1/2 can be done
UHF antennas: channel 14 λ = 25.12 inches (.64 metres)
Channel-cut (single-channel-specific) antennas: using Post #19 in the OTA FAQ you can find the required channel's wavelength to determine the best full wave or 1/2 wave spacing
Different-band antennas also need to be spaced properly:
VHF-LO with a VHF-HI: channel 7 λ = 5.65 feet (1.72 metres) apart, but 1/2 can be done
VHF-LO with an FM Radio: 88MHz λ = 11.18 feet (3.41 metres) apart, but 1/2 can be done
Either a VHF-LO, FM Radio, or VHF-HI with a UHF: channel 14 λ = 25.12 inches (.64 metres)
Can I use separate UHF and VHF antennas together?Yes, if a single Combo antenna is not suitable for your needs you can easily combine the output of a UHF and VHF antenna in several ways, with some being better than others depending on the situation at hand (that means you might have to do some testing):
combine their balun output up on the mast into a UHF VHF Separator/Joiner, such as a
Pico Macom UVSJ
Winegard CC 7870 2-Way Antenna Joiner Coupler
Antennas Direct EU385-CF UHF / VHF Antenna Combiner
if each antenna has its own preamp do as above except combine from the signal output of the preamps' power injectors into the Separator/Joiner
combine their balun output up on the mast into a reversed high quality, low loss splitter for a single coax downlead
combine their balun output up on the mast into a VHF/UHF preamp (only if amplification is suitable)
join their feed lines together with 300ohm twinlead cut half way between them, where you attach a balun and downlead
run their separate coax downleads into an A-B switch at your TV (not convenient for PVRs that cannot operate the A-B switch as needed)
I'm trying to estimate the kind of antenna I will need in order to be able to pick-up an additional digital station.
The main reason I cannot pick-up this station yet is that this station is VHF (WVNY-DT on channel 13) and that I haven't set up a VHF antenna yet.
I currently only have a CM 4221 but I am already able to pick up a weak signal at 10db SNR on channel 13.The thing about Channel 13 and the other VHF Hi channels is that a good VHF antenna will give about 10 to 15dB of unamplified gain on those channels to give a solid lock, so I don't think you should try to use your CM4221 for Channel 13 when it cannot deliver much at that frequency in the first place. Boosting it a lot could simultaneously cause big problems with the UHF channels.
Since you only want one VHF Hi channel, my advice is that you look at either (best to worst):
a precision-cut single channel antenna for Channel 13 up with your CM4221
separate VHF/FM antenna up with your CM4221 (nice to have FM Radio stations, particularly if they are HD Radio)
a good Combo to replace your CM4221 (convenience of just one antenna up there)
replace the CM4221 with a CM4228, which has decent VHF Hi reception (see next point and apply to CM4228 if needed)
CM4228 into an all-band preamplifier (might be too strong on the UHFs - you'd have to test)
(not guaranteeing this will work) stay with your CM4221 but put in a splitter from the balun, with:
one lead going into a UHF-only filter to TV
the other lead going into a strong VHF-only Preamplifier to TV
For a wide ranging discussion of the topics in this post please read through the Stacking, Ganging, Combining TV Antennas (http://www.digitalhome.ca/forum/showthread.php?t=95148) thread in the main OTA Forum.
2006-07-21, 03:30 PM
Will my analogue and digital tuners get the same reception results in the same location?
First of all, it is expected or hoped that after the transition to complete digital OTA the TV stations will operate with very similar coverage areas as their analogue stations did. This is not necessarily the case during the transition, and much work is still to be done to make sure that viewers will still get their desired OTA stations as they did before. For the purposes of answering this question lets assume that the person's area generally gets both the analogue and digital stations equally well.
With old-style analogue OTA, signals pour out from the transmitter in waves. An antenna on a house on top of a hill probably gets great analogue reception, but for other locations down the hill there might be problems that can unfortunately make the analogue signals "dirty" due to such things as terrain bounce, adjacent RF interference, multipath distortion from reflections, and more. In such cases even a great home antenna might get a miserable or at the least unpleasant signal. Oddly enough, even in generally poor reception areas analogue OTA signals can sometimes make their way and be seen satisfactorily, so there is always hope. This signal reception mess has given analogue OTA a bad rap for half a century compared to cable and satellite programming sources.
With digital OTA almost all of those analogue OTA problems have been solved. There is a big caveat to that, though. Digital OTA reception is subject to the cliff effect: if your ATSC tuner can get a lock on the signal, the programming is perfect and beautiful, but if your ATSC tuner loses that lock even for a brief time or just cannot make that lock in the first place, the entire signal goes away until a lock can be made again. The cliff effect is discussed further below in much more detail under the heading What do ATSC Signal Meters measure?
Thus, it is possible in some cases that an analogue tuner will pick up stations while a digital one will not. There are solutions, and the OTA Forum is exactly the place to go for advice and assistance.
What do I need to know about buying a tuner to get digital OTA stations?
If your TV or Home Theatre system does not contain an integrated digital tuner for OTA (called either an ATSC/QAM or NTSC/ATSC/QAM tuner) you will need to purchase an ATSC Set Top Box (STB), which means that you would plug it into one of the input ports of your HDTV and/or into an input port of your Surround Sound AV receiver. Details of exactly how to connect one will be in its set of instructions, and DHC has a FAQ and many excellent threads on Home Theatre cabling and connections should you require help or information with the hookup.
NTSC = old style analogue signals
ATSC= new style digital OTA signals
QAM = new style digital Cable TV signals (discussed elsewhere in the DHC Forums but not in the OTA Forum)The OTA Forum is, of course, filled with excellent information specifically about OTA equipment and gear issues, such as antennas, amplifiers, splitters, mounting, cabling, expected reception for your area, etc.
ATSC STBs are available from such manufacturers as LG, Samsung, Viewsonic, Digital Stream, Humax, Panasonic, and others.
Not all ATSC tuners are created equal! The latest Generation 5 and 6 chipsets are vastly improved over earlier models, so while you may find the newest models to be pricey in comparison to older "eBay specials", the performance difference is wide and very noticeable. You get what you pay for, and some poor souls have found that the "great deal" they paid for had a Generation II chipset in it, causing all sorts of reception disappointments.
Not all ATSC tuners output HD! For people who have TVs, VCRs, etc. that get only NTSC (analogue) programming a new type of ATSC tuner is available to allow reception of the new digital OTA stations. These converter boxes are not full-fledged tuners/receivers but in fact simply take the digital OTA signals and convert them to NTSC analogue. For example, the effect on watching a program is that if a true ATSC tuner provides it in 1080i High Definition resolution with Dolby Digital 5.1 audio, the converter box downsizes the image to 480i resolution with 2.0 stereo audio. Again, these converter boxes are simply to allow older NTSC gear (TVs, VCRs, etc.) to display the digital OTA programming.
Not all ATSC tuners contain analogue NTSC tuners!. If continuing to receive NTSC analogue signals is part of your OTA viewing goal, make sure that the model of ATSC tuner can receive both ATSC and NTSC signals. The better HDTVs and STBs have seamless integration of both standards into one channel-changing capability, while other models require that the user enter different on-screen interfaces for either one. Almost all of the new U.S. "coupon" boxes are ATSC only, and it is expected that Canadian consumers would just use their remotes to go back and forth between the TV's own NTSC tuner and the new box's ATSC tuner. On a modern CRT TV with Composite or S-Video inputs a consumer would hook up the ATSC tuner box in a similar fashion to a DVD player, and then select either the internal NTSC tuner for the Canadian stations or the correct input for the ATSC tuner box to watch the Canadian and U.S. digital OTA stations.
Some Bell satellite receivers have built-in ATSC tuners, but their OTA picture quality is generally not as high as with the latest ATSC STBs. Also, most satellite receivers require a satellite TV subscription/activation even to use just the ATSC tuner, so they are essentially useless as standalone OTA tuners.
The OTA Forum contains important threads concerning information, availability, technical questions, and prices of ATSC STBs and ATSC-equipped HDTVs.
What do ATSC Signal Meters measure?
ATSC Digital OTA TV broadcast signals pour out of the transmitter in waves of computer data made up of ones and zeroes, with a variety of high-tech measures added to guarantee that the receiver at the other end can take the stream of ones and zeroes and reassemble the programming in near perfect resolution and sound quality. Signal meters on ATSC tuners actually don't measure signal "strength" as one might intuitively believe, but rather the percentage of the transmitter's data packets that arrive cleanly through your antenna system and are thus able to be digitally processed.
As your ATSC tuner attempts to lock onto a station it fills a memory cache with all the data it can receive, and as a pattern forms in that data the ATSC tuner knows to look for certain cues in that data in order to lock onto the stream and commence processing it. A certain minimum amount of info is required by the ATSC tuner before it can digitally "lock" onto the signal and begin providing picture and sound. Below that threshold the tuner will not operate on that channel because the stream of ones and zeroes has been broken too much for the error-control measures to fix. This is called the "Cliff Effect" of ATSC broadcasting, in which reception is an all-or-nothing proposition. If you saw this phenomenon on a graph, it would look like a cliff. If the cliff effect is happening all the time on certain channels you may need to consider better OTA gear to get them because they are tantalizingly close to locking. Generation 5 and 6 chipsets are much better than the older ones at making and keeping signal locks.
Unfortunately there is no industry standard in place to harmonize the signal meter readings of one company's ATSC tuners with those of other brands. For example, an LG tuner owner may find that < 80% usually means no picture or sound lock on channel 39, while a Humax owner down the street may find that > 60% is required on the same channel.
Basically, unless someone has the exact same tuner in a very similar circumstance as you, the readings on your signal meter are useful just for your own particular benefit and comparison, such as when repeaking the antenna or rotating it. Even so, DHCers are encouraged to provide their signal meter results and their ATSC tuner brand/model when posting in the Results threads.
For those who require detailed signal "strength" data for their system, such as in deepest fringe reception areas, there are signal analysis tools out there but they're priced way up in the professional range and require a good knowledge of TV signal theory and practice in order to use properly. Your best bet is to contact a professional OTA installer who uses such gear and techniques to come and do a site survey for you.
Some excellent discussions of actual signal "strength" engineering theory can be found in the Understanding OTA DTV Broadcasting Technology in Canada thread:http://www.digitalhome.ca/forum/showthread.php?t=25774
2007-04-16, 05:29 PM
The official sponsor of the OTA Forum is SAVE AND REPLAY (http://overtheair.saveandreplay.com) and we thank them for their generous support and their quality OTA parts and service. :)
Where Can I Find OTA Gear/Installers In Canada?
Here are the threads in which you can find or share info on OTA Gear, Installers, etc.:
OTA: BC & Western Canada Parts, Sales, Service, Installers (http://www.digitalhome.ca/forum/showthread.php?t=51079)
OTA: Quebec Parts, Sales, Service, Installers (http://www.digitalhome.ca/forum/showthread.php?t=51078)
OTA: Ontario Parts, Sales, Service, Installers (http://www.digitalhome.ca/forum/showthread.php?t=23984)
OTA: On-Line Parts, Sales (http://www.digitalhome.ca/forum/showthread.php?t=78265)
OTA Gear From The U.S. (http://www.digitalhome.ca/forum/showthread.php?t=92505)
If you or your company are OTA Parts, Sales, Service, Installation, etc. providers please contact Hugh to advertise: http://www.digitalhome.ca/content/blogsection/3/80/
Why can't we talk about OTA prices and parts places in regular threads?
The DigitalHome web site has a separate forum for discussing where to buy items of all sorts. This is to prevent regular threads from diverting into pricing and availability discussions that tend to stray way off topic. Thus, as per the Rules Of The Forum, we don't discuss prices of OTA gear in regular OTA Forum threads.
2008-12-02, 07:54 PM
Downloadable PDF version at bottom.
To use a single-channel-cut antenna on any given TV channel in these tables, the two elements of a dipole antenna must be straight, extend exactly opposite each other, and measure 1/2 Wavelength in width from tip to tip when extended horizontally, then aimed perpendicularly to the station's broadcast antenna. A set of plain, 2 element rabbit ears is an example of such a dipole antenna. Experimentation may show as much as ±10% variance in width for best reception. Multi-element antennas meant to cover the VHF-LO or VHF-HI bands are typically generalized for the middle of the desired band.
Since FM Radio in North America is broadcast with an almost circular polarization, the receiving dipole antenna need not be horizontal as long as the two elements are exactly opposite each other, then aimed perpendicularly to the station's broadcast antenna.
For the smaller UHF TV wavelengths the elements of a bowtie antenna need to match the correct size for the desired channel. Since the UHF band is so wide, bowtie element sizes are typically generalized for the middle of the band.
DIY antenna builders and owners of telescopic-element antennas can utilize these tables to given an optimal starting point for configuring the elements for the desired stations in the area.
VHF-LO ---- (These channels are likely
to be reassigned to other non-TV uses in
most areas after the digital transition)
CH Freq in MHz Full Wave 1/2 Wave 1/2 Wave
LO MID HI Meters Meters Inches
2 54 57 60 5.26316 2.63158 103.606
3 60 63 66 4.7619 2.38095 93.7382
4 66 69 72 4.34783 2.17392 85.5874
5 76 79 82 3.79747 1.89874 74.7535
6 82 85 88 3.52941 1.7647 69.4764
FM Radio ---- (TV reception hint: a
strong local FM Radio station's
Second Harmonic can cause interference
if it overlaps the frequency of a
desired VHF-HI TV channel)
Freq in MHz 2nd Harmonic Full Wave 1/2 Wave 1/2 Wave
in MHz Meters Meters Inches
88.1 176.2 3.40522 1.70261 67.0319
88.3 176.6 3.39751 1.69876 66.8803
88.5 177 3.38983 1.69491 66.7287
88.7 177.4 3.38219 1.6911 66.5787
88.9 177.8 3.37458 1.68729 66.4287
89.1 178.2 3.367 1.6835 66.2795
89.3 178.6 3.35946 1.67973 66.1311
89.5 179 3.35196 1.67598 65.9835
89.7 179.4 3.34448 1.67224 65.8362
89.9 179.8 3.33704 1.66852 65.6898
90.1 180.2 3.32963 1.66481 65.5437
90.3 180.6 3.32226 1.66113 65.3988
90.5 181 3.31492 1.65746 65.2543
90.7 181.4 3.30761 1.6538 65.1102
90.9 181.8 3.30033 1.65017 64.9673
91.1 182.2 3.29308 1.64654 64.8244
91.3 182.6 3.28587 1.64294 64.6827
91.5 183 3.27869 1.63935 64.5413
91.7 183.4 3.27154 1.63577 64.4004
91.9 183.8 3.26442 1.63221 64.2602
92.1 184.2 3.25733 1.62867 64.1209
92.3 184.6 3.25027 1.62513 63.9815
92.5 185 3.24324 1.62162 63.8433
92.7 185.4 3.23625 1.61813 63.7059
92.9 185.8 3.22928 1.61464 63.5685
93.1 186.2 3.22234 1.61117 63.4319
93.3 186.6 3.21543 1.60772 63.2961
93.5 187 3.20856 1.60428 63.1606
93.7 187.4 3.20171 1.60085 63.0256
93.9 187.8 3.19489 1.59745 62.8917
94.1 188.2 3.1881 1.59405 62.7579
94.3 188.6 3.18134 1.59067 62.6248
94.5 189 3.1746 1.5873 62.4921
94.7 189.4 3.1679 1.58395 62.3602
94.9 189.8 3.16122 1.58061 62.2287
95.1 190.2 3.15457 1.57729 62.098
95.3 190.6 3.14795 1.57397 61.9673
95.5 191 3.14136 1.57068 61.8378
95.7 191.4 3.1348 1.5674 61.7087
95.9 191.8 3.12826 1.56413 61.5799
96.1 192.2 3.12175 1.56088 61.452
96.3 192.6 3.11526 1.55763 61.324
96.5 193 3.10881 1.55441 61.1972
96.7 193.4 3.10238 1.55119 61.0705
96.9 193.8 3.09598 1.54799 60.9445
97.1 194.2 3.0896 1.5448 60.8189
97.3 194.6 3.08325 1.54163 60.6941
97.5 195 3.07692 1.53846 60.5693
97.7 195.4 3.07062 1.53531 60.4453
97.9 195.8 3.06435 1.53218 60.322
98.1 196.2 3.0581 1.52905 60.1988
98.3 196.6 3.05188 1.52594 60.0764
98.5 197 3.04569 1.52285 59.9547
98.7 197.4 3.03951 1.51975 59.8327
98.9 197.8 3.03337 1.51669 59.7122
99.1 198.2 3.02725 1.51362 59.5913
99.3 198.6 3.02115 1.51058 59.4717
99.5 199 3.01508 1.50754 59.352
99.7 199.4 3.00903 1.50452 59.2331
99.9 199.8 3.003 1.5015 59.1142
100.1 200.2 2.997 1.4985 58.9961
100.3 200.6 2.99103 1.49551 58.8783
100.5 201 2.98507 1.49253 58.761
100.7 201.4 2.97915 1.48958 58.6449
100.9 201.8 2.97324 1.48662 58.5283
101.1 202.2 2.96736 1.48368 58.4126
101.3 202.6 2.9615 1.48075 58.2972
101.5 203 2.95567 1.47784 58.1827
101.7 203.4 2.94985 1.47493 58.0681
101.9 203.8 2.94406 1.47203 57.9539
102.1 204.2 2.9383 1.46915 57.8406
102.3 204.6 2.93255 1.46627 57.7272
102.5 205 2.92683 1.46341 57.6146
102.7 205.4 2.92113 1.46056 57.5024
102.9 205.8 2.91545 1.45772 57.3906
103.1 206.2 2.9098 1.4549 57.2795
103.3 206.6 2.90416 1.45208 57.1685
103.5 207 2.89855 1.44928 57.0583
103.7 207.4 2.89296 1.44648 56.948
103.9 207.8 2.88739 1.44369 56.8382
104.1 208.2 2.88184 1.44092 56.7291
104.3 208.6 2.87632 1.43816 56.6205
104.5 209 2.87081 1.43541 56.5122
104.7 209.4 2.86533 1.43267 56.4043
104.9 209.8 2.85987 1.42993 56.2965
105.1 210.2 2.85442 1.42721 56.1894
105.3 210.6 2.849 1.4245 56.0827
105.5 211 2.8436 1.4218 55.9764
105.7 211.4 2.83822 1.41911 55.8705
105.9 211.8 2.83286 1.41643 55.765
106.1 212.2 2.82752 1.41376 55.6598
106.3 212.6 2.8222 1.4111 55.5551
106.5 213 2.8169 1.40845 55.4508
106.7 213.4 2.81162 1.40581 55.3469
106.9 213.8 2.80636 1.40318 55.2433
107.1 214.2 2.80112 1.40056 55.1402
107.3 214.6 2.7959 1.39795 55.0374
107.5 215 2.7907 1.39535 54.935
107.7 215.4 2.78552 1.39276 54.8331
107.9 215.8 2.78035 1.39017 54.7311
VHF-HI ---- (These channels are
remaining in use post-transition)
CH Freq in MHz Full Wave 1/2 Wave 1/2 Wave
LO MID HI Meters Meters Inches
7 174 177 180 1.69492 0.84746 33.3646
8 180 183 186 1.63934 0.81967 32.2705
9 186 189 192 1.5873 0.79365 31.2461
10 192 195 198 1.53846 0.76923 30.2846
11 198 201 204 1.49254 0.74627 29.3807
12 204 207 210 1.44928 0.72464 28.5291
13 210 213 216 1.40845 0.704225 27.7254
UHF ---- (These channels are
remaining in use post-transition)
CH Freq in MHz Full Wave 1/2 Wave 1/2 Wave
LO MID HI Meters Meters Inches
14 470 473 476 0.634249 0.317124 12.4852
15 476 479 482 0.626305 0.313153 12.3289
16 482 485 488 0.618557 0.309279 12.1763
17 488 491 494 0.610998 0.305499 12.0275
18 494 497 500 0.603622 0.301811 11.8823
19 500 503 506 0.596421 0.29821 11.7406
20 506 509 512 0.589391 0.294695 11.6022
21 512 515 518 0.582524 0.291262 11.467
22 518 521 524 0.575816 0.287908 11.335
23 524 527 530 0.56926 0.28463 11.2059
24 530 533 536 0.562852 0.281426 11.0798
25 536 539 542 0.556586 0.278293 10.9564
26 542 545 548 0.550459 0.27523 10.8358
27 548 551 554 0.544465 0.272232 10.7178
28 554 557 560 0.5386 0.2693 10.6024
29 560 563 566 0.53286 0.26643 10.4894
30 566 569 572 0.527241 0.26362 10.3787
31 572 575 578 0.521739 0.260869 10.2704
32 578 581 584 0.516351 0.258176 10.1644
33 584 587 590 0.511073 0.255536 10.0605
34 590 593 596 0.505902 0.252951 9.9587
35 596 599 602 0.500835 0.250418 9.85898
36 602 605 608 0.495868 0.247934 9.76118
37 608 611 614 0.490998 0.245499 9.66532
38 614 617 620 0.486224 0.243112 9.57134
39 620 623 626 0.481541 0.24077 9.47913
40 626 629 632 0.476948 0.238474 9.38874
41 632 635 638 0.472441 0.23622 9.3
42 638 641 644 0.468019 0.23401 9.21299
43 644 647 650 0.463679 0.23184 9.12756
44 650 653 656 0.459418 0.229709 9.04366
45 656 659 662 0.455235 0.227618 8.96134
46 662 665 668 0.451128 0.225564 8.88047
47 668 671 674 0.447094 0.223547 8.80106
48 674 677 680 0.443131 0.221565 8.72303
49 680 683 686 0.439239 0.219619 8.64642
50 686 689 692 0.435414 0.217707 8.57114
51 692 695 698 0.431655 0.215828 8.49717
UHF ---- (These channels are to be
reassigned to other non-TV uses after
the digital transition is complete)
CH Freq in MHz Full Wave 1/2 Wave 1/2 Wave
LO MID HI Meters Meters Inches
52 698 701 704 0.42796 0.21398 8.42441
53 704 707 710 0.424328 0.212164 8.35291
54 710 713 716 0.420757 0.210378 8.2826
55 716 719 722 0.417246 0.208623 8.2135
56 722 725 728 0.413793 0.206897 8.14555
57 728 731 734 0.410397 0.205199 8.0787
58 734 737 740 0.407056 0.203528 8.01291
59 740 743 746 0.403769 0.201884 7.94819
60 746 749 752 0.400534 0.200267 7.88453
61 752 755 758 0.397351 0.198676 7.82189
62 758 761 764 0.394218 0.197109 7.7602
63 764 767 770 0.391134 0.195567 7.69949
64 770 773 776 0.388098 0.194049 7.63972
65 776 779 782 0.385109 0.192554 7.58087
66 782 785 788 0.382166 0.191083 7.52295
67 788 791 794 0.379267 0.189634 7.46591
68 794 797 800 0.376412 0.188206 7.40969
69 800 803 806 0.373599 0.1868 7.35433
2009-01-25, 09:15 PM
What kind of mount should I use?Some people will find that an outdoor antenna can simply be mounted onto an outdoor wall with a bracket. Condo or apartment dwellers might put their antenna on a pole weighted in a large flower planter, or clamp a pole to their deck railing. Home owners might use a tall metal pole sunk several feet into the ground. Others will need to have their antenna as high as possible to receive the desired stations so will use a roof-top antenna using a tripod or chimney-mount. For all your antenna mount needs, see the OTA Mounts, Towers, Rigging Hardware (http://www.digitalhome.ca/forum/showthread.php?t=29559) thread. How High Should My Antenna Be?In layman's terms, raising the antenna shows real benefits to a point, at which the more time, money, and labour it takes to raise the antenna past that point, the lesser the benefit per dollar/hour/back spasm is achieved (the law of diminishing returns). For this reason I only recommend tall towers to people known to be in deepest fringe areas. For some rare occasions the local conditions of other folks might dictate a tower even if they are in a closer range. For the vast, vast majority of OTA users the point of diminishing returns will never be reached because reception will have already been found to be satisfactory well below that point. Having said that, in some unusual situations reception can be improved by lowering the antenna due to local issues. Deciding on whether to use a tower should be done after reading through the Reception Results thread for your area to understand local reception issues that might require one.What about using a tower?A few OTA users will want to opt for either a guy-wired tower or a free-standing, self supported tower, while rural dwellers in deep to deepest fringe areas will likely need to use a tower 10m (~35 feet) in height or beyond. Physics tells us that apart from bearing the weight load downwards, the point of greatest strain (urge to tip over) on an antenna mast that is not free-standing is at its highest point of bracing. A free-standing mast that has no bracing or guy wires has all its points of strain occurring down where it leaves the concrete. For that reason, manufacturers make the bases of free-stading masts very stout. A non-free-standing mast will experience its maximum tipping strain at the connection point of its top guy wires, or at the location where it is bolted onto a roof end joist if no guy wires are used.
For a very Canadian example, hold a hockey stick above your head. No big deal, right? Now tape your skates onto the blade of the hockey stick and hold it above your head again. Notice that while the weight of the stick is on your lower hand, the strain of keeping it straight upwards is on your upper hand. That is the same tipping force felt by the top-most antenna mount guy wires and/or bracing point brackets.What materials are recommended for building a mast or mount?Choice of materials is critical when creating your pole or mast plans. For non-welded assembly (using nuts & bolts) your best bet is 1.5" O.D. galvanized steel conduit pipe (often called EMT for Electrical Metallic Tubing) which is common in major hardware stores in 4' to 12' lengths. It is known for its stiffness and rust/corrosion protection, as are galvanized or zinc-dipped fasteners. Welding galvanized steel is extrememly toxic so should only be done by a trained welder. If standard steel pipe is used it must be thoroughly coated in rustproofing paint before non-welded assembly or after welding. Try to use stainless steel fasteners for least corrosion. Some low-stress poles can be of extruded steel piping, but those are typically not strong enough for heavier antennas or rotor use. Plastics are not always strong enough for a pole or mast, but can be used in some situations as you can see in the ABS, PVC and other plastics for structural parts (http://www.digitalhome.ca/forum/showthread.php?t=96673) thread. Avoid using wood outdoors (even if coated) as it is subject to mildew, rot, and breakage. Pressure-treated lumber has copper product on it so must be avoided due to its mild signal-reflection properties.Is there danger of a lightning strike or other such problem?While direct lightning strikes on homes with outdoor antennas are exceedingly rare, it is still important to ensure proper grounding of your outdoor OTA gear since nearby strikes can create bursts of electromagnetic interference that could damage sensitive equipment. It is not only sensible to ground your gear properly but it is also necessary for proper home insurance protection and to meet your local electrical code. The Grounding Info & Standards: OTA/Dish/CATV/Telecom (http://www.digitalhome.ca/forum/showthread.php?t=62265) thread has everything you'll need to know about it.Should I tilt my antenna up or down?Most people can simply mount an antenna without tilting it, although in deep to deepest fringe areas it may sometimes be helpful to tilt the antenna upwards a bit. Pointing the antenna downwards is not an option. Sometimes there are situations in which the line-of-sight from an antenna to a broadcast antenna up on a mountain or tower is upwards, in which case tilting the antenna to match that line makes sense. The Tilting Antenna for Better Reception (http://www.digitalhome.ca/forum/showthread.php?t=106196) thread is dedicated to this topic.
Can I mount my antenna sideways to save space?All TV antennas for use in North America must be mounted exactly as per their instructions, which ensures that they are receiving signals horizontally. If you tip the antenna on its side it would now be vertically polarized. The reason vertical orientation won't work is that the originating signals from all North American TV stations are polarized in the horizontal plain (in some parts of the world TV was in the vertical plain but I think that's not so anymore) so a vertical antenna is only capable of picking up just the tiniest slice of signal per wave. In computer modeling of antennas for North America the vertical parts of a reflector mesh are almost dead of signal even while the horizontal segments are booming with signal.Can I put my antenna up in a tree?Nearby trees can be a problem for UHF reception, although VHF signals are much more succesful at penetrating trees and forests. Trees should never be used for mounting antennas, as discussed in the OTA: The Big Trees Factor (http://www.digitalhome.ca/forum/showthread.php?t=104178) thread.Can I run Cable TV and OTA on the same coax line?You cannot have Cable TV signals on the same coaxial cable as OTA TV signals. They use the same frequency bands so they would interfere with each other, if not cancel each other out on certain channels. Further, there would be a high risk of signal leakage, which is treated very seriously by the authorities. For more information see the Signal Leakage Between CATV and OTA (http://www.digitalhome.ca/forum/showthread.php?t=65268) FAQ.Any other tips?Always remember the old saying that what goes up must come down, so double check all the mount points and fittings for solid security. Some minor installations can be done alone, but it is always better to have an assistant for any job requiring rooftop, ladder, or climbing work. Do not mount an antenna within 2m (6 feet) of an overhead electrical utility line.
2009-07-24, 01:18 PM
Are all coaxial cables the same? Which is best?Here are the typical coaxial cable types used in OTA reception, with a brief description of their best uses:
Regular RG-6 for almost any OTA use
Quad-shield RG-6 if you have a lot of very local interference affecting the TV and/or FM Radio bands
Plenum-rated RG-6 for stringing through heating ducts has a special anti-smoke outer sheath - safety feature regarding house fires
Underground-rated RG-6 for stringing under grass, in a trench, or inside conduit that goes through a pond or high-moisture area
RG-11 for continuous lengths of over 100 feet/30 metres in any of the above situations - requires pro tools and fittings not common in stores
RG-59 for very short, flexible connector jumpers if RG-6 is too stiff to make tight bends:
at the receiver end
Messenger-type is regular, standard coaxial cable that has a separate steel wire of about 16AWG bonded to the outside of the shielding to be used for alternative purposes
For regular use without local interference across the TV bands, Quad-shield RG6 is overkill and an annoyance at crimping time, in my experience.
In the past if I wanted good RG-6 of any sort I'd go to a wholesaler and they'd cut it off their spool for me and charge by the foot or metre. Buying boxes of RG-6 in hardware stores or even Wal-Marts was not at all common. It was all RG-59 in those stores, and in short lengths.
Today the consumer marketplace has good deals on bulk or large-box RG-6 in different varieties, so for some people seeing the low prices on each type the quad-shield rating seems like a plus even though they will likely never see any OTA reception benefit to it. If they buy the quad-shield and are satisfied with its performance, all the power in the world to them :) but I would not spend any extra money on it unless I already knew there was an interference problem to be fixed.
The OTA Cabling: RG-6, RG-59, RG-11, Twin-Lead, Crimping, Other Tips (http://www.digitalhome.ca/forum/showthread.php?t=104308) thread contains a wealth of information and real world experiences with coaxial cable.