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15-20 DB difference between two TV Tuner Signal Strengths?

4282 Views 13 Replies 8 Participants Last post by Truth Be Known, 10 mo ago

Gibson_s

Discussion Starter · Jun 7, 2021

I realize TV Tuners have varying degrees of sensitivity, but my LG TV's tuner is running about 15-20 DB higher than my Sony TV's tuner. I have a Tablo that gets similar channels as my LG TV when my Sony will miss a few stations.

One of my local channels is at 61 on my Sony and 77 on my LG, it's a trend that runs through every station. My Sony also benefits from a shorter cable run from my CM distribution amp. So I'm guessing my tuner in the Sony just under performs? Is this normal to be that much difference? I miss a few channels on the Sony because of this.

I'm in a pretty strong signal area but have opted for a very frugal setup, knockoff antenna + CM drop amp. I added an LTE filter and it got me a couple more stations. I'm getting 56 total channels on the LG and Tablo, losing 1 or 2 at night. I was going to buy a preamp and see if it was better then decide to keep the drop amp or not.

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RabbitEars, where you can learn all about local, over-the-air TV channels.

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By the way, I have an old school Yagi on a 30ft tower that's not in use. The amp went bad and it just sits up there, went the cheap route because I chickened out climbing the tower

, not quite as youthful as I once was.

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RayGuy

· #2 · Jun 7, 2021 (Edited)

Odds are that the TVs are displaying some internally calculated "number", which can mean very different things in different models. Unless you are seeing more drop-outs and signal issues on the Sony, I would ignore the numbers, except as a crude measure of the relative strength of stations on a given model.

That said, some tuners are more capable that others, either in sensitivity or in rejection of spurious signals. Take any action based on performance, not reported numbers.

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Gibson_s

Discussion Starter · #3 · Jun 7, 2021

Hard to tell what's going on as today strange things are happening. Lost a very close channel and got 3 stations from Lansing, MI, 75 miles away which I definitely shouldn't be getting with my tiny antenna setup.

Got 58 channels on my Sony, most I've ever gotten with this antenna setup.

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rabbit73

· #4 · Jun 8, 2021 (Edited)

Gibson_s said:
I realize TV Tuners have varying degrees of sensitivity, but my LG TV's tuner is running about 15-20 DB higher than my Sony TV's tuner. I have a Tablo that gets similar channels as my LG TV when my Sony will miss a few stations.

Hello, Gibson_s

It is true that some tuners are more sensitive, but the difference is usually only a few dB. How did you measure that difference? The signal scales in TVs are only relative, and they might be signal strength or signal quality.

One of my local channels is at 61 on my Sony and 77 on my LG, it's a trend that runs through every station. My Sony also benefits from a shorter cable run from my CM distribution amp. So I'm guessing my tuner in the Sony just under performs? Is this normal to be that much difference? I miss a few channels on the Sony because of this.

There is another possibility, which is overload. Overload can cause gain compression, which will give lower readings for stronger channels and will make reception of the weakest signals more difficult. Example:
Strange "backwards" pickup pattern
Strange "backwards" pickup pattern - TV Fool

Note in particular post #4 by Tower Guy, a retired TV engineer:
TV Fool - View Single Post - Strange "backwards" pickup pattern

Thank you for the signal report.

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To the Signal Margin numbers on your signal report, you must add the antenna gain and the amp gain.

I was going to buy a preamp and see if it was better then decide to keep the drop amp or not.

With your strong signals, more amp gain might not be a good idea.

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rabbit73

· #5 · Jun 8, 2021

Gibson_s said:
Hard to tell what's going on as today strange things are happening. Lost a very close channel and got 3 stations from Lansing, MI, 75 miles away which I definitely shouldn't be getting with my tiny antenna setup.

Got 58 channels on my Sony, most I've ever gotten with this antenna setup.

This is the time of year for strange things. The cause is Tropospheric Propagation which enhances weak signals that you would not usually be able to receive.
Tropospheric DX Modes

https://www.dxinfocentre.com/tropo.html

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harsh

· #6 · Jun 8, 2021

Signal "levels" (dB versus signal quality versus some combination of the two) are NOT comparable between different devices as RayGuy points out.

It is possible that you're amplified signal is too hot. If you have a long cable laying around, you might test adding that and seeing if the Sony's performance doesn't improve with "less" signal.

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Gibson_s

Discussion Starter · #7 · Jun 8, 2021

Zero chance it's overload. If you saw my older system you'd realize that it's not the case. Needed a preamp and a 30ft tower to get reliable reception previously. I'm pretty close to a tall building and it was causing multipath. I used to get Toledo and some Canadian stations when I turned the rotor.

I'm really surprised I got anything with the cheapie antenna I put up 12ft high... but I had to get the NFL games I was missing and Fox 2 (RF 7 on VHF) wasn't coming in reliably until I added the drop amp (antenna only has one VHF element). I probably have 50ft of coax to the amp and 50ft to the TV's.

And yes, it went from 40% to 60% on the Sony. The LG is higher... I'm reading their signal strengths from the TV's themselves, I don't have any fancy instruments to measure the actual figures.

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Gibson_s

Discussion Starter · #8 · Jun 8, 2021

When I was messing around with the Tablo and a rabbit ear antenna, I couldn't get ABC 7 (25) at 17 miles away or the low power repeater 26 (17) which I'm only a couple miles away. Also only could get 50 (34) at 2 bars.

I don't think anything is overloading.

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Primestar31

· #9 · Jun 8, 2021

There are NO government or manufacturers standards between different devices as to what they are measuring, and what the levels are for antenna signals. 72% on my Tivo Roamio, is 100% on other devices.

So, you may NOT be seeing a real world difference between your two sets.

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Gibson_s

Discussion Starter · #10 · Jun 8, 2021

Primestar31 said:
There are NO government or manufacturers standards between different devices as to what they are measuring, and what the levels are for antenna signals. 72% on my Tivo Roamio, is 100% on other devices.

So, you may NOT be seeing a real world difference between your two sets.

Understood. My error in thinking that the numbers had some accuracy.

I don't really have any reception problems, I get the channels I need, reliably.

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gbynum

· #11 · Jun 8, 2021

Gibson_s said:
I realize TV Tuners have varying degrees of sensitivity, but my LG TV's tuner is running about 15-20 DB higher than my Sony TV's tuner.

I think you have some good answers, and reached a good conclusion. If you want to do some analysis inexpensively, buy some type F attenuators, perhaps (how we did it in 1970) a 30dB, 20dB, 10dB, and a 0-10dB variable. Stack them until you see loss of signal, then go to the other set. If you search around here, you'll find an old-timer who has done some of that; I don't remember who the author is.

We, way back when, had variable versions with type N connections and adapters for UHF, BNC, and F, but those were relatively high dollar.

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Gibson_s

Discussion Starter · #12 · Jun 17, 2021

So I added a RCA preamp and raised my bowtie antenna, now my Sony's signal strength numbers are almost identical to the other TV. I don't really know why this is, but it's getting as good reception (or better) than the other TV. Cleaner and stronger signal from the antenna must have solved the issue.

I'm getting 85% on the strong signals now, very impressed for a cheap amp. I was getting 40% on a weaker station, now it's 67%. Maybe with some fine tuning and pointing, I can better the strength.

Channel 18.1 was coming in and out, just realized it was a Spanish language station... don't know if it's worth it to go after it though. I have it pointed off a bit so I can still reliably pickup 2 stations almost due South. I still need the Hockey games on CBC 9.1 which is on the high VHF.

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ChiwaukeeOTA

· #13 · Mar 27, 2022

I see that one of the other recent tuner threads has been closed for commenting so I'll just leave my comment here. My newer Samsung has the best tuner in the house. My 20in Toshiba is not as good as my 36in Toshiba. My 36in Toshiba gets the same channel count as my Samsung but the Samsung decodes better. I'll find a station it is intermittently pixelating on my 36in Toshiba and run downstairs and check the Samsung and it might not be pixelating at all.

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Truth Be Known

· #14 · 10 mo ago

A simple test that we used in the Cable industry was called "Jumper Verify". You used a separate cable to first go from the street "Tap" to the Converter Box at the set to verify signals were clean and had good levels. You then went to the input cable to the splitter and tested the "Drop" cable to see if the issue was there. it was a simple process of elimination and did expose where the issue was. You could also disconnect all lines at the House Splitter and find out if those lines were allowing interference into the Cable system. As a Cable Tech I always replaced every connector just for preventative maintenance and always found the faults and corrected them. I was a Tech that had no time limits and was sent behind 2 to 3 service techs that had already been there. And I did find the issues.

So what's this got to do with Over the Air Issues?

The same tests could be used with TV Antenna systems. "Jumper Verify" signal readings first from the Antenna if accessible, then all output ports of the splitter one at a time to one TV and compare the signal readings on the TV. Use one TV only as a reference Set to compare signals. If you see a significant drop in level in a wire, first replace the connectors and if that doesn't work, replace the wire. Any connection needs to be looked at since wiring may have been extended and has additional connectors. If you can, replace any wire that has connections to extend them.

I had a Customer once that had an issue with Channel 5 RF only. It was a Splitter that had an RF "Notch" right at Channel 5 RF and suspect it was dropped before it was installed. 2 other Techs missed this issue.

Television Antenna and Cable Distribution is not hard, it's just many times Shortcuts are taken and that's when it gets irritating. I'm just surprised how many bad Antennas are available now days.

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