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Rabbit,
I think we mostly agree. In looking at Tripp's charts keeping in mind with what he sent to you as an explanation, I think the accounting for low channel noise is only used to determine when the signal strength is declared "bad". The calculate received signal strengths and signal margin only assume thermal noise is present. This would provide a pretty grim chance of reception with your measured noise levels. I guess mounting the antenna outside of the house might yield as lower noise level.
John
 

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I'm not sure how accurate the report is for my location, as some channels listed as poor (WHNS and WUNF) come in at 33-35dB on my signal meter (samsung tv). I have a GE 29884 outside, around 20 feet above ground level right now. I do plan on having a professional installing the antenna, it'll be the eave mount and be guyed.
Thank you for the additional information by PM. I redid your report; it's a perfect match to the one you did.
https://www.rabbitears.info/searchmap.php?request=result&study_id=110563

WGGS is a weak 2Edge signal. 2Edge signal reports are known to me much less accurate than LOS, and your location is directly behind a hill:



and you are in a dead zone (no color) on the Longley-Rice coverage map:



You will just have to make some tests. VHF signals can make it over terrain obstructions better than UHF signals. I rate it as difficult but not impossible.
 

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Rabbit,
I think we mostly agree. In looking at Tripp's charts keeping in mind with what he sent to you as an explanation, I think the accounting for low channel noise is only used to determine when the signal strength is declared "bad". The calculate received signal strengths and signal margin only assume thermal noise is present. This would provide a pretty grim chance of reception with your measured noise levels. I guess mounting the antenna outside of the house might yield as lower noise level.
John

Looks like a 25 foot mast might be in order. I figured it would be a shot in the dark either way.
 

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I think I have everything I need, here's a list of the items I have ordered. If you guys can think of anything else, please let me know.



Winegard HD8200U Platinum VHF/UHF HDTV Antenna
RCA VH226F Outdoor Antenna Rotator with Remote
Solid Signal 100ft Universal Antenna Rotor Wire
Channel Master 25’ Telescoping Mast CM-1830
Winegard SW-0012 Gable End Antenna Mount
100 ft quad shield RG6
CM-7777HD preamp
Radio Shack FM Trap


I already have guy wire and grounding wire, plus a clamp for the mast to ground it.
 

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This is going to be extremely tough if your ambient Lo-V noise is anything like mine. KVCR 5 from my house took a very large log periodic to pull in reliably. 5 performed much worse than I expected and even vs. Trip's RE projection. My signal projection from KVCR 5 is

2 is likely to be tougher, but you won't know until you try, of course. I live in suburbia where LD Lo-V's are lucky to even show the pilot!

Here's my prediction for RF 5.

24‑1 (5) KVCR-DT PBS SAN BERNARDINO CA 33.1 40.8° 29.2° 51.06 Poor 23.06 L
 

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Yah I have a the sharp 37D7U the new ones that just came out, it has the tuner built in.
I recently inherited a Sharp AQUOS LC-37D7U that is in great condition. So I hooked it up outside to my digital air antenna and I can't get any digital channels. All it says is Analog. Even swapped it out with an antenna that I know works and it didn't work. Any suggestions? I am sure this older TV does have a digital tuner built in. Heard something about firmware. Is there a new edition and can I download and install it?
Thanks in advance
 

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I recently inherited a Sharp AQUOS LC-37D7U that is in great condition. So I hooked it up outside to my digital air antenna and I can't get any digital channels. All it says is Analog.

Are you sure it's set to "Antenna" and not to "Cable?" This is the first thing to check when a channel scan shows nothing.
 

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I recently inherited a Sharp AQUOS LC-37D7U that is in great condition. So I hooked it up outside to my digital air antenna and I can't get any digital channels. All it says is Analog. Even swapped it out with an antenna that I know works and it didn't work. Any suggestions? I am sure this older TV does have a digital tuner built in. Heard something about firmware. Is there a new edition and can I download and install it?
Thanks in advance
Read this manual page, you need to scan using the antenna setup - digital - air screen. p.s. There's NO such thing as a "digital antenna", so any tv antenna will work, even an ancient one IF it's for the correct band of stations in your area:

https://www.manualslib.com/manual/151577/Sharp-Aquos-Lc-26d5u.html?page=43#manual
 

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Measuring TV Signal Strength with an SDR

Sometimes it is necessary to measure the strength of TV signals, and you want more than a number from a percent scale. Signal level meters are expensive, but you can use an SDR to view the signal and obtain a signal strength measurement if you have calibrated the SDR. The measurement will actually be signal power because the units are in dB.

Most SDRs have a relative signal strength scale in dB or dBm instead of an absolute value scale.

The SDRplay RSP2 SDR has, it is claimed, a calibrated signal measurement system. They have a video which shows that measurements with an SDR of signals from a signal generator are quite accurate.



I tried a few measurements with my SDRplay RSP1A SDR as a test and found that it works with an NTSC video signal from a frequency agile modulator:



I then wondered if it could be used to measure a digital TV signal. Some signals don't have a flat top, like CH13 in my avatar to the left. My Sadelco DisplayMax 800 signal level meter makes 43 measurements across a channel, takes an average, and adds a correction factor of +6.8 dB to match a noise source derived from NIST. If any one of the 43 measurements is below -20 dBmV, the meter reads Ur.



CH16 TEST
Settings:

8 MHz span
FM WFM 192K

DisplayMax 800: -13.0 dBmV = -61.8 dBm
SDR: -76.2 dBm calibrated
76.2 - 61.8 = 14.4
-76.2 dBm + 14.4 correction factor = -61.8 dBm

If the top of the signal isn't flat, it's up to you to place the measurement window at an average level point in the scan, which is at least as good as a meter that does a 280 kHz wide measurement at the center of the channel.





CH16 at Dropout:
Added sufficient attenuation to bring tuner SNR down to 15 dB
(Added preamp only before meter to keep reading above -20 dBmV and subtracted its gain)
DisplayMax 800: -37.2 dBmV = -86.0 dBm
SDR: -100.5 dBm calibrated
100.5 - 86.0 = 14.5
-100.5 dBm + 14.5 correction factor = -86.0 dBm at Dropout



Most tuners dropout around -85 dBm; close enough.

If you are using a preamp, dropout might be at a lower dBm value (more likely on UHF than on VHF) if the Noise Figure of the preamp is less than the Noise Figure of the tuner.

Good reference by Calaveras:
Signal Strength, Signal-to-Noise Ratio and Other Related Issues in DTV
http://www.aa6g.org/DTV/Noise/noise.html

Now that I know the correction factor, I don't need my signal level meter. If I have any doubts about the correction factor, I only need a variable attenuator for a double check.

Even if you don't have a signal level meter, you can calculate the correction factor with an attenuator and dropout at about -100 dBm (uncorrected) on the SDR. It's the difference between the SDR reading and -85 dBm.

The dropout test should be done with a UHF channel. The ambient noise level on VHF is higher than the Thermal Noise Floor of -106 dBm for a 6 MHz channel. This means that dropout will be at a level higher than -85 dBm because the VHF signal needs to be stronger to have sufficient SNR above the higher VHF noise level. Simplified calculation of minimum required signal:
-106 dBm Thermal Noise + 6 dB tuner NF + 15 dB SNR = -85 dBm



Here is a test on CH11:
800: -5.3 dBmV - 17 preamp just for meter = -22.3 dBmV = -71.1 dBm
SDR -85.4 dBm calibrated
85.4 - 71.1 = 14.3
-85.4 dBm +14.3 correction factor = -71.1 dBm

The correction factor for CH 11 is similar to the factor for CH 16 when I measure the strength of CH 11, but when I do the dropout test for CH 11 the correction factor is larger because of the higher noise level on VHF:
800: -16.6 dBmV -17 preamp just for meter = -33.6 dBmV = -82.4 dBm
SDR: -99.3 dBm calibrated
99.3 - 82.4 = 16.9
-99.3 dBm + 16.9 correction factor = -82.4 dBm at dropout



The correction factor error is even worse if you do the dropout test on VHF-Low.

I did noise level measurements on some vacant channels. It was necessary to add preamplification to make the Sadelco 800 meter more sensitive:

Antenna > 7777HD 30 dB > Sadelco 800 meter
CH 8: -2.7 dBmV - 30 = -32.7 dBmV = -81.5 dBm
CH 13: -1.9 dBmV - 30 = -31.9 dBmV = -80.7 dBm

CH 20: -18.8 dBmV - 30 = -48.8 dBmV = -97.6 dBm

Antenna > 7777HD 30 dB > 7777HD 17 dB > Sadelco 800 meter
CH 27: +0.1 dBmV - 47 = -46.9 dBmV = -95.7 dBm
CH 41: -5.4 dBmV - 47 = -52.4 dBmV = -101.2 dBm

To check measurement system:
75 ohm termination resistor > 7777HD 30 dB > 7777HD 17 dB > 800 meter
CH 41 with 75 ohm resistor: -10.5 dBmV - 47 = -57.5 dBmV = -106.3 dBm; OK

If you set the SDR gain too high, it will overload:

 

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Thanks for everyone's help. Got my HD8200U installed today, took 3 people. Still need to tweak the height some, as I lost one channel, but I did get the channel I was trying to get. I'm around 40 feet above ground level.

Congratulations, it looks like the big antenna at 40' was worth it, guy wires and all! I'm looking forward to putting up my large VHF as well.
 

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Thanks for everyone's help. Got my HD8200U installed today, took 3 people. Still need to tweak the height some, as I lost one channel, but I did get the channel I was trying to get. I'm around 40 feet above ground level.

I hope it holds in for you. A signal strength of 3/10 and an SNR of 20 dB is pretty iffy for RF 2. That implies the Noise Margin may only be 5 dB which would be very low. It'll probably be unwatchable whenever thunderstorms are in the area. I can't even watch RF 9 with a NM of 15-20 dB when there are thunderstorms within 100 miles. :(
 

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Thanks for everyone's help. Got my HD8200U installed today, took 3 people. Still need to tweak the height some, as I lost one channel, but I did get the channel I was trying to get. I'm around 40 feet above ground level.



https://www.dropbox.com/s/t31cb482e36z340/IMG_0176.JPG?dl=0


Will post pictures, once I get everything tweaked.
Glad you got WGGS and hope it holds. It can be problematic even locally here in Spartanburg County. It was much easier to receive before the repack when it was on RF16. And they carry primarily religious programming and some home shopping channels. But since I get Jimmy Swaggart from WJZY, I haven't worried much about WGGS. But now you can at least see what Jim Bakker is up to these days, since none of the Charlotte stations seem to carry his current program.

But will be interesting to see your pics and signal reports once you get it all said and done.
 

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I was up in WA again this past weekend for the 4th and did all kinds of things to improve Hi-V reception. After many different tweaks, I've pretty much concluded that pre-amps on Hi-V are of little to no benefit, at least for the short 6' cable runs I have to my tuners. It definitely helps UHF quite a bit, however. I tried 3 different pre-amps and various sets of attenuators.

What I found most interesting is that the classic CM 7777 pre-amp was passing FM radio on the UHF side even with the VHF side trapped. That was a bit of a shock and my FM trap wasn't in. It is now, but it does little for the 3rd strongest station there (88.1). So, I will filter VHF on the UHF input next time. It definitely isolates Hi-V but not FM radio. I have 3 LOS FM stations from Capitol Peak, at about 18 miles, one of which is a whopping 70kW.

I've mostly been able to get KCTS now from Seattle, but I put up the big Stellar 30-2476 in the attic to make it (mostly) reliable.

Here's the latest results.

https://m.rabbitears.info/index.php?request=tvdx_grid&tid=1047C0BC&tno=1&sort=all&hours=168&tzone=PT&unit=&auto=Y

I have the Hi-V into the pre-amp still, but it's for convenience and not necessity.

I recall rabbit had some explanation on why pre-amps don't help on VHF, so I will look for it. Any additional comments re are welcome, of course.

Edit: Added a pic of the current attic setup (DB4e and 30-2476) and more FM radio info.
 

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I was up in WA again this past weekend for the 4th and did all kinds of things to improve Hi-V reception. After many different tweaks, I've pretty much concluded that pre-amps on Hi-V are of little to no benefit, at least for the short 6' cable runs I have to my tuners. It definitely helps UHF quite a bit, however. I tried 3 different pre-amps and various sets of attenuators.


Thank you for the interesting report from WA. It looks pretty crowded in that attic; must have taken a while to do the setup.

On UHF, a preamp will amplify a signal, amplify the noise, and add its own noise. Since the NF of a good preamp is less than the NF of a tuner, the system noise figure is improved according to the Friis formula because the preamp is at the headend of the system.
https://en.wikipedia.org/wiki/Friis_formulas_for_noise

On VHF, where the ambient noise level is higher than -106 dBm, the system noise figure calculation and the lower NF of the preamp become irrelevant because they are based on the thermal noise floor of -106 dBm. The NFs of the preamp and the tuner are both buried in the much higher ambient noise. All you are left with is the same SNR that you started with because the preamp amplifies both the signal and the noise the same amount. Your only hope is to reduce the noise, unless you can find a location for the antenna with a better SNR.

You will notice there is no place to enter the elevated noise level in the System Noise Figure Calculator:



I quote Calaveras:
http://www.aa6g.org/DTV/Noise/noise.html
Figure 5 adds 10 dB of noise to the received signal. This requires 10 dB more SS to get the same SNR and NM. External noise added to the system acts like a high noise figure amplifier with unity gain. The effective noise figure is just like calculating System Noise Figure. It doesn't take much external noise to ruin the benefits of the preamp when the added noise is much higher than the preamp noise figure. Even external noise that's only equal to the preamp noise figure significantly degrades the System Noise Figure.
Your WA scan:



Unfortunately, the same thing can happen when you increase the antenna gain. When I switched from an indoor folded dipole for VHF-High to a 30-2475 Yagi, the signals were much stronger, but so was the noise, resulting in no improvement in SNR.



I have 3 LOS FM stations from Capitol Peak, at about 18 miles, one of which is a whopping 70kW.
Is this FM report correct? I don't know of any other place to get an FM report other than TVFool.
http://www.fmfool.com/modeling/tmp/b4b45ee87e/Radar-FM.png
I've mostly been able to get KCTS now from Seattle, but I put up the big Stellar 30-2476 in the attic to make it (mostly) reliable.
Sounds like an improvement to me.

My noise on VHF-High is much worse than on UHF



See also this post about my channel 9. I compared an indoor antenna with an outdoor antenna. The outdoor antenna had a better SNR; less noise:
Building Attenuation Test, Method 3
https://www.avsforum.com/forum/25-hdtv-technical/1256344-research-communications-preamp-owners-3.html#post56595346
 

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Thank you for the interesting report from WA. It looks pretty crowded in that attic; must have taken a while to do the setup.
Thanks, rabbit. Yes, quite. We bought the house over a year ago and I've been trying to get up every month (I missed 2 months due to C19) and I have worked on it on every trip up there. It's been quite a process as the attic has blown in insulation and just enough floor boards to service the furnace unit. On the trip prior to this one, I installed enough floor boards to access the area the Hi-V is in now. It's still very cramped as most modern homes in earthquake-prone areas are.

Is this FM report correct? I don't know of any other place to get an FM report other than TVFool [FMFool].
http://www.fmfool.com/modeling/tmp/b4b45ee87e/Radar-FM.png
Yes, that FM report is pretty accurate, but the signals are stronger from Capitol Peak than Tacoma.

I also found out that the Ethernet noise wasn't a factor. I removed the Ethernet over AC and swapped in a WiFi bridge.

I DID find out that the Air TV [it's the original - there's a 2 now it seems] box puts out quite a bit of noise around RF 9 and 10. I will move that box away from everything when I can find a cabler who actually wants to work. It will be far too complicated for me to run coax to even a few rooms.

The blown-in insulation is about 20" deep and is essentially "lava" to anything I have dropped into it (more things than I care to admit). I don't wear my wedding ring into the attic for this reason.
 

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The Stellar Labs 30-2476 VHF antenna features the ability angle it up towards the atmosphere. In what circumstances would this improve reception?
If I am targeting a marginal station 70 miles away over hilly terrain, would angling it up one notch improve performance?
 

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The Stellar Labs 30-2476 VHF antenna features the ability angle it up towards the atmosphere. In what circumstances would this improve reception?
If I am targeting a marginal station 70 miles away over hilly terrain, would angling it up one notch improve performance?
Hello, onslowtn

You have asked a general question without giving any details like a signal report or what station you are trying to receive.

WSPA?

All we can give is a general answer that it might help in rare cases; you must try it to find out.

Keep in mind during your test that OTA signals are constantly changing in strength. Do you have a way to measure signal strength and/or SNR?
 
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