AGC Issue

Status
Not open for further replies.

JamesO

Member
Joined
Jan 22, 2003
Messages
1,816
Location
McLean, VA
What radio are you working with?

I am not convinced it actually works or does anything based on my experimentation. Additionally if it is on a radio with the 2-3 different settings, nowhere have I ever seen a guide, description of settings or a White Paper on how any of the setting affect a signal.

Might try setting up 2 identical systems, one with and one without the AGC enabled and see if you notice a difference.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,516
Location
Stockholm, Sweden
It's an audio AGC that tries to even out the min and max. It's hardly noticable, if it at all works.
On the BCT15 and HP-1 one can adjust the settings to make a bigger change to the audio and at max settings it will give a very noticable pumping effect in the audio.

There haven't been any reports of how to access the AGC settings in the x36 series.

/Ubbe
 

dallascowboys

Member
Premium Subscriber
Joined
Feb 23, 2009
Messages
680
Location
Dothan Alabama
Good Morning,

Thanks for all the info on this, I did leave out one thing this AGC is a DIGITAL AGC on my BCD436HP , as of right now in Sentinel under my county it has the AGC set to on.
Again should this be on or set to off ? Again thank you for all the info on this.
 

Markscan

Member
Premium Subscriber
Joined
Jan 9, 2004
Messages
583
Location
New Jersey
I leave mine off. It doesn't seem to work anyway.


Sent from my iPad using Tapatalk
 

majoco

Member
Joined
Dec 25, 2008
Messages
3,723
Location
New Zealand
AGC does nothing for an FM or FMN signal - in fact the gain is probably maximum and amplitude variations are clipped off (limiting) to prevent noise spikes getting through.

AM (aircraft band) may be helped with AGC on to help smooth out signal amplitude variations to bring audio up to the same level.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,516
Location
Stockholm, Sweden
AM AGC is a different thing and acts on the gain of the RF to not clip the AM modulation.
AGC on FM and digital is pure audio level control.

My AOR AR8200 actually have RF AGC on FM as well. You can select to have it active on FM and when you come near a tower that usually creates intermod mess with another scanner the AOR reduces gain to avoid this. It is very apparent as you loose the coverage but rather that than listening to intermod. But it also fools you thinking that the scanner has an incredible frontend when you never hear any interferencies.

/Ubbe
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,516
Location
Stockholm, Sweden
I tested the analog FM AGC, and it should be valid also for digital AGC, and it is working.
I entered a DMR channel, that transmits data with 2 sec intervals, as an FM analog type only and tested AGC on and off with squelch open.

Without AGC the noise are easily noticed as being much louder than the data signal.
Using AGC the audio level is equal for both noise and data and when data starts the level of audio is first low and then increase very fast during a few milliseconds to equal the noise level.

It could benefit by having a bigger dynamic gain, as I have manually set in BCT15 and HP-1, but as long as we don't have access to the service menu we can't do much about it.

But as the AGC actually works I recommend to always have it on. You normally only disable AGC if you get annoyed by the pumping effect from the audio. No risk with that when Uniden uses these kind of moderate default values.

/Ubbe
 
Status
Not open for further replies.
Top