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View Full Version : AGC gone from 80 to 2, should I be worried.


Ojustaboo
12-11-19, 13:35
When I last had a problem with my setup, which turned out to be the skew, the AGC was around 80 (both before and after I adjusted the skew).

A few days ago we lost the signal for about 30 seconds (wasn't raining, and rain doesn't usually affect it anyway unless it's a cloudburst), haven't lost it since.

Looking at random channels over the past few days , the AGC is always the same, it's only 2% compared to the 80% it used to be at.

Since I last fixed my skew problem until a few days ago, I hadn't bothered checking the signal strength as everything was working fine.

Should I be worried with only 2% AGC (it's more that it used to be 80% that's made me query it), or should I simply put loosing the signal down to a fluke with the weather?

My SNR is now also always 100%.

(I am running vix 5.2.043, not the latest version)

For example, here are two screenshots taken today

5941859419

and here is a screenshot taken a few months ago

59421



Many thanks
Ojustaboo
12-11-19, 16:24
Just updated to ViX 5.3.009 and it's the same
twol
12-11-19, 16:56
Which receiver is it????????????
Ojustaboo
18-11-19, 17:33
GiGaBlue HD-ULTRA-UE
twol
18-11-19, 17:35
As long as you are receiving without issues, I wouldnt worry
adm
18-11-19, 21:32
Just updated to ViX 5.3.009 and it's the same

What is the AGC (Automatic Gain Control) figure actually indicating? Traditionally an AGC attempts to normalise the input to a fixed level for the following stages hence a high input and a low gain applied and conversly a low input and a high gain applied.
If you have improved the level of your input signal then an AGC would apply a lower gain. This is perhaps what the AGC figure on the box is showing.
CRMS
07-08-20, 16:55
Interesting. I'm now foreign with the same LNB, receiver, DC injector and splitter as a couple of days ago in UK.
In UK 100 SNR, 2-4% AGC and 16.5 dB.
In FR Tuner A is the same but Tuner B AGC has shot up to 100%.
Nothing changed. Rebooted, no different.
Strange??
adm
07-08-20, 20:11
Interesting. I'm now foreign with the same LNB, receiver, DC injector and splitter as a couple of days ago in UK.
In UK 100 SNR, 2-4% AGC and 16.5 dB.
In FR Tuner A is the same but Tuner B AGC has shot up to 100%.
Nothing changed.

So you are using the same undisturbed cables from the LNB to the splitter and the same undisturbed cables from the splitter to your box?
Badly made cable or F plug connection?
F plugs not fully screwed home?
Kink in the cable? Are you using a cable with foam dielectric that resists kinking better?

Swap A and B over to see if the AGC values swap over.
Have you got any unused outputs on any of your splitters? If so terminate them with a 75 ohm load.
example


https://tinyurl.com/yyahgbqv
BrianTheTechieSnail
08-08-20, 00:08
Have you got any unused outputs on any of your splitters? If so terminate them with a 75 ohm load.
example


https://tinyurl.com/yyahgbqv

But note that if there is power or 22kHz signalling on the unused port(s) you really need a 75 ohm load that presents 75 ohms at RF frequencies only, while being high impedance at DC or 22kHz.
I'm afraid I have no idea if such loads are or are not easily available.