[App_rpt-users] USB audio and telemetry timers

[David McGough]

Hi Everyone,

Well, since I haven't heard of any solutions to my USB audio choppiness
issues, I decided to have a go at it myself. I've added several hacks to
chan_usbaudio.c that GREATLY improve the sound quality on my system. Now,
false DTMF decode events are infrequent for me--as compared to sometimes
occurring every few seconds. The trade off is that I'm letting a few
frames of "real" DTMF tone pass thru the system without muting before
deciding that a DTMF tone is really present.

Also, I have experimentally modified the soundcard_writeframe() function
slightly. Now, this source is raspyness is improved, too.

I'll post code for evaluation if anyone is interested.

73, David kb4fxc




On Thu, 3 Sep 2009, David McGough wrote:

> 
> Hi everyone,
> 
> I've been using app_rpt for well over a year now on a home UHF repeater
> that includes 2 remote bases (HF & VHF). For the hardware interface, I'm
> using DMK Engineering URI adapters. This config has worked fairly well,
> overall.  But, so far I've used this system casually.
> 
> Over the last few weeks, I've finally gotten "serious" about implementing
> some new repeaters, etc., for local ham community. So, I'm now trying to
> iron-out the remaining issues and, wondered if anyone else has already got
> solutions.
> 
> To start with, I "upgraded" to the latest and greatest by installing the
> most recent ACID release on a new AMD X2 Athlon 64 6000+ box (MSI
> K9N6PGM2-V motherboard, 4GB RAM). I was, at this point, running the latest
> CentOS 5.3 and app_rpt version 0.174.  I immediately hit problems. The
> telemetry timers were getting "stuck" (e.g. the idrecording would stop and
> the transmitter would hang keyed until timeout) and audio was sporadically
> moderately garbled....
> 
> So, I download the latest SVN version (v362).  This helped, but, problems
> persisted....So, I download the most recent kernel (2.6.30.5) and
> compiled. I wanted to use the high-res kernel timer, and had to patch
> ztdummy.c to support the most recent (as of 2.6.28?) kernel interface API.  
> This GREATLY improved everything! No more timer issues, etc., so far!
> ...zttest now reports timer consistancy of 99.997%!
> 
> 
> But, I still have 2 longstanding issues that I'd love to find resolution
> for. First, I'm still getting a fairly frequent stream of warning messages
> like:
> 
> 	WARNING[xxx]: chan_usbradio.c:1640 soundcard_writeframe: write: used 3 blocks (1)
> 
> And, these messages accompany somewhat choppy (or raspy)  audio when they
> occur. I've seen these messages on several different boxes. So, it doesn't
> seem to be specifically hardware or kernel related.
> 
> Second, I'm still seeing fairly frequent false DTMF decoding. This, too,
> causing a momentary choppiness (muting) in the audio. On some peoples
> voices, this false decoding (and chop) is severe. Last year I added some 
> explicit code to chan_usbradio.c to disable DTMF decode, and, this problem 
> was temporarily hidden. But, now I need DTMF decode--so, disabling isn't 
> an option.
> 
> Thanks in advance for any help!
> 
> 73, David kb4fxc
> 
> 
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