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autogain


Patrick Perdue
 

Hi all:

For the entire time I've been using DVSwitch, I've had usrpAudio=AUDIO_USE_Gain on Analog_Bridge. I'd like to use AGC, as dynamic range from DMR can be quite wide, but I find the attack and release to be way too fast, yielding a very crunchy effect, even with moderately hot DMR audio. Decreasing the gain just turns down the output. The input is still just as squished, just quieter. I like the idea, just want a smoother implementation of it. I think increasing the release time a little, and perhaps raising the threshold slightly would improve things, but I don't see a way to do this. Is this possible at all with the algorithm currently being used? If so, could this be added as a set of user adjustable parameter in Analog_Bridge?

Thanks and 73

de

KE4DYI


Mike Zingman - N4IRR
 

Partick,

Thanks for the message.  When I put the AGC code in, I was playing with several functions and never really did finish the work on this.  Today I looked back. at what was included and it is pretty rough.  So, I am playing with a new (for me) algorithm and it seems to perform much better than the included code.  Not sure how I will expose the tuning parameters (threshold, slope and decay), but I am continuing to test.  If I allow dynamic updates to the parameters I will have to protect the internal structures from being modified while audio is present.  

For me, the modes with the greatest range are DMR and DSTAR on the loud end and fusion on the quiet end.  Not that the AMBE is different, but the different radio manufactures tend to have vastly different front end gains defined by default.  Playing on several of the bridges where all of these modes tend to be present.

Mike N4IRR   


Patrick Perdue
 

Hi Mike:

Very cool. Thanks for looking at this.

I agree re digital modes. Also, Fusion radios tend to have some dithering built-in, or something. There always seems to be some constant low level white noise on those radios when in YSF mode, for some reason. I don't hear that on DMR or DSTAR. To be fair, I don't have any YSF equipment myself, and am hearing this through DMR, but theoretically, that shouldn't matter.


On 4/13/2020 5:07 PM, Mike Zingman - N4IRR wrote:
Partick,

Thanks for the message.  When I put the AGC code in, I was playing with several functions and never really did finish the work on this.  Today I looked back. at what was included and it is pretty rough.  So, I am playing with a new (for me) algorithm and it seems to perform much better than the included code.  Not sure how I will expose the tuning parameters (threshold, slope and decay), but I am continuing to test.  If I allow dynamic updates to the parameters I will have to protect the internal structures from being modified while audio is present.  

For me, the modes with the greatest range are DMR and DSTAR on the loud end and fusion on the quiet end.  Not that the AMBE is different, but the different radio manufactures tend to have vastly different front end gains defined by default.  Playing on several of the bridges where all of these modes tend to be present.

Mike N4IRR   


EA3BIL_Rafa
 
Edited

As far as I've been able to "see", YSF does always show low audio level when received on DMR.
I guess it has some kind of link to the need to use YSF on DN modulation when using multimode nodes.
Anyway, in the same line if thinking it does not make make sense when they use their YSF only nodes (so they can use DW and theorically improved audio response) and I have the same results on DMR side.

I agree about comments on low audio level.
It looks like a "brand mark" on YSF.

Anyway it's easy to fix:
Tell the colleague on YSF to SPEAK UP.
;)