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Old 06-18-2014, 9:02 PM
Join Date: Mar 2010
Location: San Diego
Posts: 1,249
Default XT scanners, how to properly configure AGC

Trying to figure out AGC. Could someone familiar with adjusting these settings explain each one. Primarily looking for descriptions of how each setting affects audio in a particular way, with examples of what "pumping" sounds like, and how to know when you have adjusted a setting too far in any direction. Do digital and analog have to be matched, or balanced?

I am more interested in making the low level audio louder than I am making loud audio lower. Thanks.

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Old 06-18-2014, 9:50 PM
Join Date: Jan 2003
Location: McLean, VA
Posts: 1,735


This is a specific thread that I was considering posting for some time, however, I going to have a LOT of questions about the AGC.

I also wanted to really look around before I posted anything to make sure I did not miss anything in the documentation regarding the AGC function and settings.

So here is a quick stab at it.

1. Do not know the x96T plaform, but the x96XT platform and the x36HP platform both have very similiar AGC configurations. Both have an Analog and Digital AGC setting with a number of user specific adjustments. The HP1 only has an AGC ON or OFF setting, not nearly as complex as the x96XT and x36HP platforms.

2. My first question, and this is a honest questions is does the AGC actually work or do anything on these radios?? I have played with the AGC a bit and have failed to really see a difference if the AGC is On or Off and what if the minor adjustments really change or do anything.

3. I really think Uniden should write some sort of Application Note for the AGC settings and configuration. This Application Note should include specific examples of settings and how they impact the signal and/or audio.

4. Is the AGC an RF or Audio AGC?

5. What would a good default or balanced AGC configuration look like.

6. Detail how each adjustment affects the Audio and/or RF section of the radio.

Maybe I have missed the Holy Grail of AGC documentation and someone can just link it here, but I have looked pretty good and this subject was going to be one of my next items to solve and conquer.

As for the original question as how to make low level audio louder than I am making loud audio lower I use the Audio Offset on these radios all the time. This is fine to address consistently loud or quiet systems, but may not be a good option for a system that has a large variation of audio levels.

For example the State Police in my area has rather loud audio as compared to most other systems. So I use the Audio Offset to adjust the State Police audio levels down to match most of my other systems I monitor. Then my local County Trunked system has a few of the State Police TGID patched onto the County Trunked system. These TGID are very loud, so I again balance the audio level with the Audio Offset.

The other thing I do is usually adjust up by +1 or +2 the Audio Offset for specific TGID's in my County System that are Priority or Important TGID's. This along with an Alert Tone and/or LED color/pattern it helps me "hear" the difference on a specific TGID. This is also helpful if the audio level has been turned down a bit my my wife or kids or if there are other conversations in the room my Priority/Important TGID's are easier to hear and allow me to focus easier on.

So anyone that can offer any AGC insight would be appreciated, has anyone actually run any test or can confirm if any of the AGC settings actually work. Also has anyone been able to stabilize and of the P25 Trunked systems with AGC and how was it set.

Any and all comments welcome as I did an initial search and came up empty handed on the subject of AGC, how it works, how the settings differ, what are the optimum settings and how has it improved reception.

AOR AR5000+3 & SDU, AR8000, Icom R71A, R7100, PC-R1500 PRO2004, IC-R1500, PRO2006, PRO43, PRO96, PRO-197, PRO2096, BC785D, HP1E, 396XT, 325P2, 996XT, 996P2, 436HP, 536HP. Probably missed some gear.
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  #3 (permalink)  
Old 06-18-2014, 10:21 PM
Join Date: Mar 2010
Location: San Diego
Posts: 1,249

My probable misunderstanding of Uniden AGC is that it samples for several number of time or whatever, then adjusts up or down to the set limit number to try to average the next set of samples, and begins the process again. This may be totally incorrect, and adjusting the parameters based on this belief could end up making things worse or not making any change at all, so wanted to pin this down.

I use volume off-set mostly on conventional systems that are too loud compared to my 800 trunked stuff, or to bring up air band low level AM stuff. For the county-wide trunked system in San Diego, the agencies on it are so varied in their audio quality, you can normally tell which one is talking not only by the dispatch console tone, but also by how the mobiles and handhelds sound. Perhaps the system admins have adjusted the TX AGC in the Motorolas, since airport units are around loud noises, and patrol officers sneaking around sometimes need to be able to whisper and be heard.

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