How can I measure signal gain in DB of a TV signal?

jmoffat

Joined Jul 18, 2012
42
I can't answer your question but your 10.5 dB amp is split 4 ways. The output may be equal or less than the input. Then there is the signal to noise issue. If the original signal is very weak then the output will have a high level of noise.
 

SLK001

Joined Nov 29, 2011
1,549
Some TVs have a signal level available somewhere. My Sharp has it in a digital channel setup menu. My VIZIO has it in the SYSTEM INFO menu. These indicators are usually in dB, with some arbitrary reference, so they can only be used for relative measurements.

If this dist amp replaced a passive 4-way splitter, you should see about 3 to 3.5dB higher output power on each port. You would need a network analyzer to make the measurements you want.
 

#12

Joined Nov 30, 2010
18,224
45 years ago, I was installing TV antennas. Sears handed me a meter that measured microvolts right out of the antenna terminals and I could tune in any channel. That meter cost over $1000. Maybe it's cheaper now.
 

Thread Starter

spinnaker

Joined Oct 29, 2009
7,830
Some TVs have a signal level available somewhere. My Sharp has it in a digital channel setup menu. My VIZIO has it in the SYSTEM INFO menu. These indicators are usually in dB, with some arbitrary reference, so they can only be used for relative measurements.

If this dist amp replaced a passive 4-way splitter, you should see about 3 to 3.5dB higher output power on each port. You would need a network analyzer to make the measurements you want.

Yeah I have an HDHomerun tuner and a Haupauge tuner. Both have power meter software. I am going to do some experiments with that. The problem is they only go from a 0 to 100 scale. Makes it a little difficult for a good comparison but it might do.
 

Thread Starter

spinnaker

Joined Oct 29, 2009
7,830
45 years ago, I was installing TV antennas. Sears handed me a meter that measured microvolts right out of the antenna terminals and I could tune in any channel. That meter cost over $1000. Maybe it's cheaper now.
I ordered one of these.

http://www.ebay.com/itm/182180902279?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

But then later I realized I wasted my money (never order late at night ;) ). But maybe it will help me see if each of my antenna's are working anyway (I have two).
 

GopherT

Joined Nov 23, 2012
8,009

SLK001

Joined Nov 29, 2011
1,549
Your ebay box is for pointing satellite antennae that has a low noise block converter at the head (you shoot for the highest signal).
 

Thread Starter

spinnaker

Joined Oct 29, 2009
7,830
Your ebay box is for pointing satellite antennae that has a low noise block converter at the head (you shoot for the highest signal).

Not according to the description. Last I checked satellites are non-terrestrial. Though I guess their receiving antennas are. ;)

DVB-T Finder Digital Aerial Terrestrial TV Antenna Signal Strength Meter US
 

Externet

Joined Nov 29, 2005
2,201
I have one of those indicators for aiming my satellite receiving dishes. It works, but they have a front end LNB mixer/receiver and preamplifier at the focal point that yields a much higher signal than a few microvolts a plain television antenna yields. So I doubt it will work. And it is designed for aiming towards a signal showing the peak azimuth/elevation, not to read signal power/voltage value.
 

BR-549

Joined Sep 22, 2013
4,928
Do you really need to measure it? I picked up a small battery powered lcd color tv for under 60 bucks a while back (a few years). It's handy when the power goes out. I would think one could find an exceptional deal right now.

I use it with the antenna on my roof. My antenna rotator does not indicate direction of antenna. I just rotate 'til clear picture.

Work's great. You can check the whole feed system thru-out the house.
 

#12

Joined Nov 30, 2010
18,224
not sure what an actual signal from a TV Antenna should be
When I was doing this job, 300 uvolts at the antenna terminals was considered 100% sufficient.
How in the world I remember that number from 45 years ago is amazing:cool:, but that also means a lot can change in 45 years.:(
Still, it's any measurement at all.
 

snav

Joined Aug 1, 2011
115
I ordered one of these.

http://www.ebay.com/itm/122062463786?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT

It is a booster that is supposed to have a 10.5 db gain of a TV signal. I am not seeing much of a performance increase over my non powered splitter.

Is there a way to measure the gain? I have a scope, will I need some kind of filter or amp to measure the signal?
Best way to do it is get a converter, (given out for free during transition) and use built in signal strength functions. Most have outputs that will connect to any video input. Something like this http://www.ebay.com/itm/USA-1080P-H...763469?hash=item48a0d2040d:g:EPwAAOSw-5RZi8Im

but a giveaway at flea market or craigs list. Without proper tuner cheap meters can't tell you the BER and bad signals look the same as good ones.
 
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#12

Joined Nov 30, 2010
18,224
35 years ago I bought a battery operated TV and tapped into the AGC signal. 100% portable. That allowed me to tune a station and measure the peak direction. Now we have boxes which do all that, better and cheaper!

All I have to do is choose a channel, turn the sound up, and listen to the tone while I turn the antenna.
Of course, it's more convenient with a helper to change the channels, but it can be done alone.
 
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