[TenTec] AGC Threshold, RF Gain, Volume

[Charles Harpole]

Same issue/problem on new K3.....
Charles Harpole
 
 
k4vud at hotmail.com 
 
 
 
 
 
> From: hjohnc at gmail.com> To: tentec at contesting.com> Date: Sun, 11 May 2008 19:14:57 -0400> Subject: Re: [TenTec] AGC Threshold, RF Gain, Volume> > Thanks Merle!> > That was a good explanation of what I was experiencing. I like version 2 > firmware, but will try v1.373b5. I've tried it before, but never for long > enough to get used to it.> > 73 de K1ESE> John> > > ----- Original Message ----- > From: "Merle Bone" <merlebone at charter.net>> To: <tentec at contesting.com>> Sent: Sunday, May 11, 2008 3:15 PM> Subject: [TenTec] AGC Threshold, RF Gain, Volume> > > > John,> > Yes the RF gain control changes the AGC threshold level - just like > > setting> > it in the AGC menu. One of the original Orion firmware developers, Doug> > Smith, wrote in a paper describing the Orion Digital AGC System:> > -----------------------------------------------------------------------> >> > "In digital AGC systems, it is relatively easy to provide a variable> > threshold or "knee." Input signals below the threshold do not actuate the> > digital AGC and are not compressed. At thresholds well above the receiver> > noise floor, a receiver therefore gets quiet when only puny input signals> > are present in the passband. At thresholds near the noise floor, all > > signals> > are boosted to meet the output-level criterion. The net effect of a > > variable> > threshold is very much like that of an IF gain control."> > ------------------------------------------------------------------------> >> > Consequently, if you "ride the RF gain" and set it for a good audio level > > on> > a stronger signal, weaker signals will not activate the AGC and they will > > be> > too low in volume. I've never been fond of this process. I think it was a> > "crutch" to offset the gain distribution issues in the new Orion V2> > firmware. There was an AVC loop in the V1 code that prevented the audio> > stages from being overdriven and distorting. That code was taken out of > > the> > V2 firmware and there have been peak signal distortion issues since. That> > started some people doing what you described with the audio and RF gain> > controls. Unfortunately you are seeing some of the unintended consequences> > of operating the radio like that. Hopefully Ten-Tec will address the> > distributed gain level issues in the next Orion V2 firmware release - > > maybe> > they will put the ALC code back.> > 73, Merle - W0EWM> >> >> > _______________________________________________> > TenTec mailing list> > TenTec at contesting.com> > http://lists.contesting.com/mailman/listinfo/tentec > > _______________________________________________> TenTec mailing list> TenTec at contesting.com> http://lists.contesting.com/mailman/listinfo/tentec