: Splitters, Attenuators, Filters, Diplexers, Other Signal Gear
2006-01-16, 04:24 PM
The easiest way to check for leakage between 2 sources is to disconnect the regular TV's CATV and OTA inputs and put a portable TV with rabbit ears right beside it. On the portable TV do a full channel scan of both TV and CATV and make note of which channels you receive and also which other ones are really garbled.
Next, hook up the regular TV's inputs again and turn it on as well as any set top boxes needed, then on the portable TV do a full channel scan of both TV and CATV. If you are now receiving more channels than the with the first scans on the portable TV (even if they are garbled but strong signals) then you have leakage. If not, your TV is properly isolating the inputs.
Another thing you can do if you're not sure is check your TV's manual or contact the manufacturer to find out if they're isolated.
macker, let us know the make/model of your TV and what you find out. :)
2006-01-16, 04:43 PM
Be aware that if you use an RF Modulator to connect a DVD player, VCR, XBox, or other electronic gear to your TV because it only has a coax (RF) input, you must not put your RF Modulator and your OTA connection on a splitter feeding into the TV. If you do, you will cause signal leakage that will mess up everything you try to view and maybe that of your neighbours too. Industry Canada might even fine you when they triangulate in on your location.
2006-01-16, 09:23 PM
They probably don't care as much about interferance with OTA as with other services. Cable channels use frequencies other than TV, including aeronautical band, etc.
2006-01-17, 08:54 AM
The make and model is RCA Scenium HD65W20. The only info I've found is
"Deluxe Shielded Tuner with 181-Channel Tuning Capability = Check your cable company's compatibility requirements"
So hopefully this means that they are isolated
2006-01-17, 09:36 AM
If we could redo CATV all over again I'd advocate assigning a third range of frequencies apart from TV and Satellite.And what range of frequencies would you choose? (there isn't exactly a surplus out there!) Correct me if I'm wrong, but I think the problem plaguing CATV systems has traditionally been the inability to effectively distribute channels using higher-frequency assignments due to increased signal attenuation. Nowadays, they're getting into super and hyper bands that nearly mimic UHF frequencies, but they can only do this because of the recent feasibility of sending optical fibre signals to individual neighbourhoods and then doing relatively few amplify-and-split coaxial trunks to peoples' homes. In the "olden days", when the whole CATV system was copper coaxial cable from headend to customer premises, it was very hard to maintain all channels at a uniform signal strength, since upper channels attenuate quicker than lower-frequency ones. In other words, this is why crappy, who-watches-that kind of channels were assigned "high" channel numbers since few people really cared that you got a crummy, noisy picture on them.
I tried to look for a decent website that shows all the frequency allotments, but this is all I could find:
So, if you simply connect the antenna and the CATV with a splitter you will cause signal leakage of the CATV signals through your antenna and vice-versa, which will cause garble and interference not only for yourself but for your neighbours too. Connections like that are ILLEGAL. Industry Canada and CATV providers constantly check for signal leakage and will come down really hard on you if you let it happen.Is there really any proof of this kind of heavy-handed action against private citizens? I mean, if someone accidentally spliced their CATV connection to their OTA TV antenna, and started radiating minute amounts of interference into the airwaves, are the Industry Canada goons going to come and arrest you and treat you like some kind of ruthless corporation? I mean, the average CATV drop has what, 0dB signal strength? You might be lucky to cause interference with someone else's reception down the street, but it's not as if you're going to actually ruin the signal propagating from a 500,000 watt commercial transmitter stick hanging 500 feet in the sky.
I'm not saying this is completely laughable -- just that when you talk about actually doing tests to make sure a multi-input TV actually has sufficient isolation between CATV and OTA inputs, c'mon. I doubt the feds would bust down your door for using a piece of consumer equipment how it's intended to be used!
What is the solution then? An A-B input switch is one method, or if your TV has 2 coax inputs you could test to see if they are discrete (separated inside to prevent leakage). Some people run the OTA lead right into the TV and the CATV lead into the VCR and then over Composite or SVHS into the TV. There are a few solutions like that if you think about it. I think there might be remote control capable A-B CATV/Antenna coax switches out there too.Has anyone found a remote-control A-B switch? I've been looking for one that is not infrared, but it seems impossible to find.
2006-01-17, 12:29 PM
Here's a much better TV frequency chart from Tin Lee Electronics:
Also mr.ous, as ShawnD was getting at, and as HDTV101 has some great info on, certain leaking CATV frequencies can directly affect aircraft Instrument Landing Systems due to overlap. Signal leakage is taken extremely seriously in areas near ILS-equipped airports, meaning where the vast majority of Canadians live. Or look at it from the CATV side: some preamped OTA antennas are outputting as much as 25 to 30dB gain through their downleads, so having that bleed into a cable system is really not cool.
So which is better, to inform readers about this topic or to just let it ride?
2006-01-17, 02:57 PM
I wasn't trying to ridicule your cautionary note. I mean, there's all kinds of information out there about this:
I just took a bit of an exception to what I interpreted as a dire warning. DBS home satellite systems typically convert 11.7-to-12.2 or 12.2-to-12.6 GHz signals from the LNBF to 950-to-1450 MHz ones sent through the downlead to the receiver. I would hesitate to call them "not a problem" -- it's just more difficult, I suppose, to cause 'common' interference problems. If you have one of those in-line satellite booster/distribution amps and don't know what you're doing, you could cause just as much trouble with your local cable company, other radio signals in the airwaves, the feds, etc.
Plug in a spot welder? You cause electrical spikes within the local circuit. Short out your phoneline or attempt to send power down it maliciously/inadvertently? You probably won't blow any of Bell's equipment, since they usually have protection devices in place, but they'll probably send a tech to your door, eventually. Attempt to suck juice out of high-tension power lines by putting massive induction coils in close proximity? You might be in trouble with some hydro officials.
Heh, I guess I'm just saying I'm surprised that increased awareness is being sought, when I'd hope most people eager enough to investigate OTA HDTV would know you can't use a splitter 'backwards'. Maybe it's valid since a lot of people have grown up not having a clue that you can even pick up channels off-air, and so they have very little experience with MATV type systems. Still, some TV sets are so poorly manufactured with respect to leakeage that if you're within reasonably vicinity of an OTA TV transmitter site, you can get better than a total snow image of reception without anything even connected to the 75-ohm antenna jack; that's just the nature of consumer equipment, and I don't see how the consumer can be held responsible so long as they made all the proper connections.
2006-01-17, 04:52 PM
Disagreeing with me is quite alright, by the way. ;)
2006-01-19, 02:37 PM
Hello from Vancouver. Kudos to all participants of this forum - it is a great resource and one of the reasons I love the Internet.
My HP/Panny PE4200N ED plasma has built-in ATSC/NTSC/QAM tuners but only one RF input. I'm looking for the best solution for utilizing both analogue cable and an OTA antenna signals. If I understand the info provided by Stampeder, an A-B input switch would work. I have a couple questions about this solution:
1) Any recommendations for a good switch that is remote controllable?
2) With an A-B switch installed so that I can select one of either the OTA antenna or the analogue cable signal, is it likely that my TV will retain in its channel memory both the OTA channels and the analogue cable channels or will there be some conflict that prohibits all available channels from co-existing?
The other possible solution is to connect the OTA to the TV's RF input, and connect the cable to the VCR and then connect a composite video out from the VCR to the TV. I have a couple questions about this solution:
1) With this configuration, I would be using the VCR's tuner for the cable channels, right? Therefore, I would not be able to record something on the VCR and watch a different cable channel at the same time, is that correct?
2) Using a composite video cable from the VCR to the TV, is the picture quality likely to suffer compared to the existing coax connection between the VCR and the TV?
If I understand things correctly, a remote controllable A-B switch is the best option - provided that my TV will retain all available channels in its memory without any conflicts (re-scanning channels every time I switched inputs is not a viable option in my opinion).
Thanks in advance for the guidance.
2006-01-21, 03:30 PM
Gee, I thought people would jump in with advice for you, cohoho... here goes... ;)
First, read up on the various connection types in the DHC FAQs so that you can tell what they are capable of when hooking up components like VCRs. In there you'll see that for VCRs and DVDs it is preferable to use composite over RF.
OTA is a different consideration since your TV has a built-in ATSC tuner, so you have no choice in this matter: you must run the OTA antenna coax lead directly to your TV's RF input since it is going to be inputting ATSC (HD 16:9 DD5.1) signals to its tuner.
Then I would run the analogue CATV lead into the VCR since it is going to be inputting NTSC (SD 4:3) and that's what the VCR is made for. Do a channel scan and that will load up all the analog CATV stations you are getting.
Then, based on what the VCR offers for connections, use the best one that it can do. If its composite, so be it, because it is generally better than RF for NTSC programming.
Regarding TV Channel memory, you would use the TV's for OTA, and the VCR's for CATV.
I think this is the simplest/best setup for you since it doesn't require any additional purchases and it gears the signal source to its best medium in your particular case. It also avoids the problem of signal leakage discussed in this thread: http://www.digitalhomecanada.com/forum/showthread.php?t=36675
If your TV has two ANT inputs, you could put a splitter upstream of the VCR sending one cable to the VCR (and to the TV via composite), with the other cable split to the ANT2 of the TV.
That way you could tune to the analogue cable signals on the TV on ANT2, while recording another channel. I'm not sure if it'll work or not as some people have reported that even with two tuners, they could not do this (one tuner ATSC, one NTSC....
You could also get a digital STB for cable doing the same "split" but sending the split to the cable STB and then from the cable STB to the TV via the appropriate connection (composite, S-video, component (if HD)). If you get this complex, see the Digital Home FAQ "how to connect a VCR & STB".
2006-01-21, 04:35 PM
That model has just one RF input, but 1 HDMI, 2 Component, 2 S-Video, and 1 PC(RGB), so we can forget about composite from the VCR:
Unless your VCR has S-Video, you would need to use its RF-out line. That takes us back to an A-B RF switch idea:
OTA going to the A-B switch
CATV going to the VCR's RF-in
VCR's RF-out going to the A-B switch
A-B switch going to the TV's RF-in
There are composite to S-video adaptors. They're relatively inexpensive. A search on the web will find lots, if you end up needing one.
2006-01-21, 05:07 PM
Attached is the list of inputs/outputs on that PE4200N TV as seen in the HP documentation. This clarifies everything. The connection solution then is:
OTA going to the TV's RF-in
CATV going to the VCR's RF-in
VCR's Composite Video-out going to 3rd Party S-Video adaptor-in
S-Video adaptor-out going to the TV's S-Video-in
VCR's Analog R-L Audio-out going to the TV's R-L Audio-in that correlates with the S-Video-in being used
Composite-to-S-Video adaptor: http://www.hometech.com/video/svconv.html
2006-01-21, 06:42 PM
First thing, make sure your TV can scan all kind of signal on the same setup.
I have a LG PVR with two RF inputs and I canít scan NTSC-OTA and CATV all together. I always have ATSC but I have to choose between OTA-NTSC and CATV/CADTV.
With only one RF input, maybe you will have to choose between TV/DTV and CATV/CADTV.
2006-01-23, 01:37 AM
Wow, thanks for the excellent discussion folks. Actually, regarding the available video inputs on the HP PE4200N, the TV Authority info is wrong, and the HP excerpt above (which I think is from the spec sheet) is misleading. The TV actually has 1 RF in, I HDMI in, 2 sets of component video in, and 2 sets of composite video in.
Here's the user guide (but beware - it's a big 11.3 MB PDF file)
Anyway, with the TV's single RF input being used for an OTA antenna, it seems for NTSC analogue cable, I can use a composite video cable from the VCR to the TV. Would there be any advantage to converting this composite video to S-Video and using that input on the TV instead of the TV's composite video input?
The problem with the above hookup would be when the VCR is recording something, I wouldn't be able to watch a different channel on analogue cable. However, if there isn't a better solution that could combine the OTA antenna and analogue cable into the single RF input on the TV, then I guess that is what I'll have to accept for now.
2006-01-23, 09:12 AM
cohoho you still use a vcr to record ? :)
You have to go with the configuration you listed and use a S video cable from the vcr if it has that output. Picture should be slightly brighter and sharper.
If you dont have a s-vhs then dont bother to buy a converting box from composite to s video not worth it.
2006-01-23, 04:07 PM
Yaamon - my wife uses the VCR to record her s*!#. It's a Panasonic VCR with only RF and composite video outs available. I would like to get a DVR to replace it but I want to be able to record HD content and right now there doesn't seem to be a lot available. The Sony DHG-HDD250/500 would fit the bill but they are discontinued - I may pursue one of those on eBay or something. Otherwise, I'll just bide my time until the right DVR comes along. I know that the satellite TV providers and cable TV provider has PVRs available but I only have OTA and basic cable (no set-top box) and right now I'm not very keen to be on the cable company's hook for any more money each month as I really don't watch enough TV to justify it. Well, that's the way it is for now anyway.
2006-01-23, 06:49 PM
cohoho buy a home dvd recorder with a hard drive. Much better quality than a vcr?
Will have component outputs and S video too. :)
Something to consider. Good luck.
2006-01-25, 11:27 PM
From the DHC Rogers Forum: