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Apparently doesn't take much signal to be able to watch
TV.
That's long been known as one of the advantages of digital signals. Depending on the modulation & reception methods, it's even possible to recover a signal that's below the noise level, something that's pretty much impossible with analog. If you look at the digital TV transmitters, you'll find they're running much less power than the old analog transmitters.
 

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Yeah, I know.
Wouldn't mind looking at a typical Link Budget for ATSC TV reception.
Happen to know of something to look at online, lemme know...
 

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That's long been known as one of the advantages of digital signals. Depending on the modulation & reception methods, it's even possible to recover a signal that's below the noise level, something that's pretty much impossible with analog.
Amateur radio operators have been doing that for a while with PSK31. The desired signal is typically below the noise level but the software pulls it out and makes a usable signal.
 

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Wouldn't mind looking at a typical Link Budget for ATSC TV reception.
Happen to know of something to look at online, lemme know...
TVFool.com interactive maps feature is a good start. You can see the receive power level at any location you which on google maps. Click on the station id, and you can gt a colour coded power level map.

It won't do the rain fade part of the link budget, though, if that's what you're looking for -- just terrain-based propagation issues.
 

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The fol. should help to sort out the different Signal Level Meters.

1. Inexpensive "Satellite Signal Level Meters" are ONLY good for aligning SAT dishes:
http://www.solidsignal.com/pview.as...Tone-(SF99)&c=Signal Meters&sku=2I7SF01005354

2. Inexpensive "OTA Signal Level Meters" are simple, full-band energy detectors which
are useful to align OTA DTV Antenna...but ONLY when ALL desired LOCAL, STRONG towers
are in the same location---which hardly EVER happens in real world applications:
http://transatelectronics.com/store...r_P561?zenid=ddfc331826d4f674fafb055ca6cde549

3. Some CECB Converter Boxes have been cross-calibrated against professional Signal Level Meters:
http://www.avsforum.com/avs-vb/showpost.php?p=16166929&postcount=9117
Probably the least expensive way to measure signal strength on a channel-by-channel basis
and will measure very weak signals.
Some USB Stick Tuners also display Signal Strength (e.g. HDHomeRun, et. al.) but I have not
(yet) seen any data re cross-calibration to professional Signal Level Meters.

4. There are VERY FEW low cost OTA Signal Level Analyzers which can display receive levels
for individual channels. Here's the Digiair Pro for just under $200:
http://www.solidsignal.com/pview.as...-(DIGIAIR-DB)&sku=DIGIAIR PRO&source=googleps
However, it will not measure very weak signals, so consider using a Preamp with it.

4. There are numerous Analog TV "Field Strength Meters" appearing from time to time
on the used equipment market. An adjustment factor is needed to convert from Peak Reading
for Analog to Average Reading for Digital. Correction may vary from model to model:
http://www.pi-usa.com/pdf/dtva.pdf
http://www.boonton.com/pdf/AN50.pdf
BTW: If the "Field Strength Meter" comes with an antenna, it's intended to measure
the very strong signal levels in the vicinity of the transmitter....not the receiver....

5. Pricey, professional OTA/CATV Signal Level Meters with increasing levels of useful features:
White Paper from 2003: http://www.sencore.com/uploads/files/Analyzing_Signal_Quality_of_TV_RF_Signals.pdf
Some are CATV ONLY, whereas some do both OTA and CATV. Some even add SAT band.
http://www.sencore.com/products/rf-analysis/
Carefully check the minimum signal level capability....many are intended for CATV use
and have limited sensitivity when used for OTA.

6. Expensive Spectrum Analyzers that can display multipath degradation and various sorts
of interference, whether co-channel, adjacent channel or intermodulation distortion.
Some of the more expensive Signal Level Meters have this capability built-in.

Additional info:
http://www.avsforum.com/avs-vb/showthread.php?t=1084674
 

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Digiair pro

I'm considering getting a DIGIAIR PRO to help aim tv antennas, and was wondering if their any good for the new digital channels, as I see no mention of ATSC in the manual.
 

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After a couple of seconds of hard Googling, it appears it does do ATSC. BTW, the name is also a clue.
 

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Witchdoctor, I moved your post into this thread mostly because of Post #45, which is a must read for someone wanting to buy a suitable OTA signal analyzer or meter for their needs and budget.
 

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Digiair pro

I have had my unit for nearly 2 years and - yes it works well for ATSC stations as well as NTSC. There is a selection which enables it to track both types of signal. I last used it to peak a Winegard 9032 antenna on CICT-DT here in Calgary. I must say that it is invaluable for use on the roof with no TV screen in sight or a body to shout the signal strength readings as you are adjusting! :)
 

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I had this DigiAir Pro, and it did not have a switch for ATSC, it was NTSC. So that the readouts were too low, to be of use.

Where is the switch for the ATSC?

Thanks! Id give it another shot if it worked for Fringe signals, and had an ATSC switch. Perhaps a new version was put out?
 

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A Portable OTA Signal Finder Setup (See Post #53)

Here is a option for those who wish to hunt for OTA reception hotspots.



The heart of the setup is the 7 inch "MyGoTV" DPT170D+ battery-powered ATSC TV. Great TV for this because 1) it has a capable ATSC tuner, 2) it is lightweight and battery-powered (rechargeable proprietary only), 3) it has a signal strength indicator and a manual channel-add option, and 4) the 800 x 480 display is really quite nice. A bit pricey, yes, but try the "Big River". This unit is also sold under a different brand and model number at R. Shack (Auvio High-Resolution 7").



The idea was to maximize mobility (on foot), without worrying, for example, about dropping a $1000 laptop-USB tuner rig off the roof (yeah, you could use a netbook, but it's still a lot to wrangle). So I aimed for a stable lightweight platform that could hold an antenna and TV and free up one's hands to move it around, fiddle with the channels, etc.

I went the 1/2 inch PVC route, with lots of fittings ($15 worth!). There are certainly other ways to put something like this together. What's nice about the PVC and fittings is that they are snug enough to be secure without glue or screws, so the whole thing can be quite modular.



The antenna shown is the Fracarro-style X-032 4-diamond, built approximately to the specs supplied by Xauto http://www.digitalhome.ca/forum/showpost.php?p=949752&postcount=184 . I like this antenna because it is easy to build, has no eye-poking elements, and pulls in signals very well. You could swap in a different antenna, as long as it's not too heavy. The lower mast is metal electrical conduit, which works nicely because it is strong, and narrow enough to fit through the cross and into the T on the base. You can also shed the base and carry the rig around like a staff. Or do without the portable TV and connect it to your cable run into the house (but then you have to bug a family member to get on the phone with you and...well, it sort of defeats the whole purpose).
 

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That's a great idea, jpasadena, and a GH or M4 could be substituted for the 4-diamond with ease for UHF.

For VHF a person could use simple rabbit ears on top, but for longer distances there would be a need for at least a small LPDA - all a person has to do is manoeuvre one on a pole with a length of coax to where your base unit sits.
 

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Nice work ! Besides using it for locating the hot spots, it could also be used to tweak phasing lines and elements/reflectors in real time. :p For wi-fi, tweaking in real time using net stumbler helped me get another 2 dBi out of my bi-quad. Its amazing that little tiny changes did so much.

A bit pricey, yes, but try the "Big River". This unit is also sold under a different brand and model number at R. Shack (Auvio High-Resolution 7").
Theyll be coming down in price. Ive seen some smaller ATSC units go on sale for less than $80. (dont know about the quality of their tuners though)
 

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Signal measurement for overload.

I have a Tektronix 475 (DM44) and several multi-meters. The scope is 100MHz limited. I don't know about the multi-meters. Are the overload values quoted in this thread RMS or peak-to-peak. Is there a method to measure for signal at the antenna? I was going to attach a 75Ohm resistor across the inner core and the outer shield and connect a scope/meter across this. Is there a circuit, device, method to measure the antenna voltage?

I have a Kworld ATSC-110 which has a horrible front-end (12DB noise figure guesstimate). I also have ~70ft of cable and want to add an additional three devices. I am in the M8V xxx area of Toronto. Here is the femon summary output (from linux dvb wiki (signaltest.pl)).

Summary statistics:
Frequency Signal Ber Unc
========= ======== ======== ========
473028615 99.6 % 0.0 0.0
497028615 65.9 % 1443.6 182.3
509028615 99.3 % 0.0 0.0
527028615 98.2 % 0.0 0.0
533028615 94.7 % 0.8 0.0
545028615 67.2 % 9507.6 136.1
557028615 45.5 % 5952.8 133.0
581028615 99.0 % 0.0 0.0
587028615 97.5 % 202.4 8.5
617028615 99.2 % 0.0 0.0
623028615 97.4 % 152.0 0.0
629028615 99.1 % 340.8 0.0
647028615 99.4 % 0.0 0.0
653028615 99.2 % 0.0 0.0
659028615 63.5 % 3223.2 204.0
683028615 99.4 % 0.0 0.0
707028615 94.9 % 6507.2 0.0
773028615 98.1 % 0.0 0.0
779028615 99.4 % 0.0 0.0
785028615 99.4 % 0.0 0.0

I would order the Research Comms amplifier if I knew there would be no overload. I know that if I was to point my antenna directly at the CN tower, the CICA analog signal would overload it. However, I am pointing slightly east of grand island and expect about -25DB drop due to the side lobes. I would prefer to have some measurements before ordering. With the strength of the CAD the Research Comms and TinLee are about the same amount.

Calculations put peak signals at about 41dBm (from WNLO) and theoretically the RC amp should be ok.

Before I made my own ground, I had used the one Rogers installed. I was able to get sparks from the RG6. Rogers had connected to plumbing which contacts heating ducts which run millimeters from single strand knob and tube. With a ground stake and two separate ground wire, I don't seem to get this type of voltage anymore.

Thanks for suggestions.
Bill Pringlemeir.
 

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I have a Kworld ATSC-110 which has a horrible front-end (12DB noise figure guesstimate).
I suggest that perhaps you look into upgrading the tuner before laying out for an expensive pre-amp. There are much (MUCH) bigger gains to be made that way.

And only then spring for the RC if the signal you want is teetering on the edge. Otherwise the Kitz ought to be just as good.

Cheers
 

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Replace PCI tuner card (was:how to measure antenna signal to check for overload)

I suggest that perhaps you look into upgrading the tuner before laying out for an expensive pre-amp. There are much (MUCH) bigger gains to be made that way.
Err, ok. Do you know of a PCI ATSC Tuner card that works under Linux that has a better front end? Is there a thread for that? I also wish to add another capture card, an LCD Tv and an old NTSC set by splitting the signal four ways. Also, I still have 70ft of cabling in front of this. The cost of the PCI cards is about $80. Getting another is as much as a CM7777 and couldn't over-come the cable loss (and future splitters) like a pre-amp could.

Also, I don't see how 'much bigger gains' are to be made that way. I thought the first amp in the system was the dominate factor. If I amplify by 25dB gain with a 1dB NF, then most items coming after the pre-amp don't matter afaik.

Sorry, I am confused.
 

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Also, I don't see how 'much bigger gains' are to be made that way. I thought the first amp in the system was the dominate factor. If I amplify by 25dB gain with a 1dB NF, then most items coming after the pre-amp don't matter afaik.

Sorry, I am confused.
I think you've hit the nail on the head. Just that mlord is also pointing out the fact that no matter the preamp, sometimes it's really hard to get over that cliff using some of the early generation tuners. I can attest to that.
My usb pc tuner quite often can't get over the cliff on weak stations, yet every other tuner in the house can.
Also kinda depends on what environment ur in, Like if ur in a rural area, far away from nearby transmitters, urban trash,
A pre-amp will help immensly, because your are most likely "noise limited". When your in the city, close by to transmitters
and other sources of trash, you may be "interference limited" when using a pre-amp. No pre-amp is gonna help ya overcome interference.
in fact may just make a bad situation worse. There is also the factor of some tuners are not able to handle really strong signals as well as others. At least I think that's what he's gettin at.

I live in the suburbs south of Buffalo, and there is no way I can receive canadian digital stations reliably without a pre-amp.
(Very low Noise Margins, 1 EDGE IN MY tvfool)
I'm almost there, but still room for improvement in my setup. Mainly due to sloppyness/laziness on my part.

Noise limited: Where reception is most limited by the noise floor, i.e. - just plain weak signals
Interference limited: Decent strong signals in the area, yet still poor quality / bit errors.

Everyone's environment is different which is why you'll get so many seemingly contradictory results/opinions.
What really matters is what works for you, not what works for the other guy...

have a look at this sheet, and try plugging in ur own numbers...

http://docs.google.com/fileview?id=...WItMjE2OS00ZWQ4LTk0YjYtZWM2NDlkOTFlMTNj&hl=en
 
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