[App_rpt-users] My update regarding audio droput problems with USB FOB audio output.

[Steve Gladden]

My status is still at a point where I'm trying to get a good handle on 
being able to compile some custom Linux kernels that work..
I have some brushing up and getting up to date to do on this as my last 
few attempts have not produced a working kernel yet..

I need to be able to do this in order to at least try the semi-fixes 
that Dave suggests by using his modified code as well as using  relaxed 
DTMF decoding...

I've thoroughly convinced myself that there are issues with intermittent 
dropouts / intermittent choppy audio on all systems I have tested
regardless of CPU speed motherboard chipset, integrated video/USB etc. etc.

I will update when I have a chance to try my custom kernels and Dave's 
posted fixes

For anyone questioning these dropout issues I'd be happy to work with 
you live and give you an over the Internet live audio feed
physically patched to the audio output of any of my test systems where 
you can hear the audio intermittently chopping out while we look at live 
events and live debug data.

The way I am testing (which makes all of the dropouts far more obvious 
and detectable) is by running the audio output from the USB fob to a 
good set of amplified speakers..
setting TX timeout very high issuing a radio key and listening the the 
transmitted PL tone as well as a CWID beacon sent every 60 seconds (you 
get used to it.)

The audio dropouts are prevalent as ever on every system I've tested so 
far which specifically includes:

* Pentium3 450Mhz all Intel chipset.
* Pentium3 600Mhz Intel chipset
* AMD Duron 1.1Ghz all in oue mother board system VIA chipset.

* AMD Athlon64 system NVidia motehrbaord (NForce3) with AGP Nvidia video 
card.
* Intel Core2 Quad 6700 Nvidia SLI750i motherboard with Nvidia PCI/e 
video card

* Intel i5 (2.66Ghz) Asus P7P55D Motherboard (Intel P55 Express chipset) 
woth PCI/e video card.

* AMD Turion64 Laptop (2.2Ghz CPU) also tried turning off speedstep 
locking CPU at full speed.

* HP Laptop with Intel P4 3.2Ghz (Single core) CPU Intel chipset.

* Virtual Machine on AMD Turion Laptop: has same audio dropouts + it's 
own new audio pops due to virtual machine/usb share (this is expected)

I've noticed the frequency of the dropouts on all systems to be about 
the same.. but the 'sound' of the droputs changes
with CPU speed... on the very slow systems you can actually hear the 
'putter putter putter' sound they make..
On very fast systems you hear a quick 'zipping sound'.

This occurs seeming randomly but on average 3-5 times in any 3 minute 
span of time..
Especially around the beginning and end of the CWID but not always there..

At this point I'm speculating (but I'm not an expert or software/driver 
guy) that the routine handling sending data to the USB
fob is being inappropriately interrupted by something else (or 
everything else) when it should not be..
In my experience this routine  should have some type of exclusive (or 
nearly exclusive) use of the CPU/bus while the data is being sent
(timer interrupt routine I am guessing) to the USB device. :-)

Thanks!

Steve N8LBV




















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