[App_rpt-users] First experience with ACID app_rpt & usbradio audio popping problem.

David McGough kb4fxc at inttek.net
Thu Nov 12 18:56:39 EST 2009

Hi Steve,

What exactly do you mean by "popping"?? Is it a loud POP! like a drum or 
is it a momentary audio drop-out or choppiness??

The reason I ask about choppiness is that I've experienced this issue. 
But, I've never had loud POPS! ....

73, David kb4fxc

On Wed, 11 Nov 2009, Steve Gladden wrote:

> Short version:
> *Installed ACID
> *Have audio popping problem with USB transmit (output) audio.
> *I'm not surprised didn't expect it to work perfectly first attempt.
> *Only tried one combinarion of hardware/cpu/motherboard so far.. I need 
> to try other motherboards/CPUs.
> * Tried 3 different USB devices and ports.
> * played with moving interrupts disabling motehrboard built-on hardware etc.
> * CPU runs at about 10% while USB radio is active..
> * Loading PC heavily by running gzip -9 seti at home Lots of disk access 
> lots of network activity seem to have zero impact on the popping 
> frequentness.
> * I'd like to know if anyone else here has had this or similar problems 
> with consistent audio from the USB device (CM-108) and what they may 
> have done
>   to make it work better.
> Long Version:
> I gave it a go and went the 'easy' route just to get started..
> I ended up trying it out on that 1.1Ghz AMD Duron CPU rack mount server..
> I must say I'm extremely excited & please with this software..
> But it would be too good to be true if it all just worked first try.. 
> and of course would take all the 'fun'
> out of getting it to work..
> Ok enough small talk (haha)
> Here's what I have going on:
> Everything works except I am getting intermittent audio popping in the 
> audio output of the USB sound device.
> VERY intermittent maybe about 3-4 'pops' every minute on average.. 10 at 
> most sometimes.. and other times several minutes go by without a 'pop'.
> It seems to mostly occur during the CW ID beacon which I have going 
> every minute..
> The pops that are heard only happen when the 'transmitter' is active 
> sending PL or CW ID or PLAYBACK...
> My test arrangement has "radio key" running to produce continuous PL and 
> occasional audio popping.
> There is no radio actually hooked up yet.
> OK will talk about the hardware a bit.. and probably worse case scenario 
> here due to an 'all in one' motherboard..
> It's a MSI 6378 'budget' Athlon board.. everything built on.
> Has USB 1.1  *NOT 2*
> I don't know/think this matters for a sound device.
> Here's all of the things I have tried all of which have absolutely no 
> effect on the intermittent popping...
> 1. Disabling everything not needed on motherboard including ethernet for 
> test..
>     ethernet + usb share an interrup line and there is no ability to 
> re-route this in the bios
>     so I turned off the ethernet on the motherboard for testing.
> 2. Carefully monitor CPU during audio pops running 'top' around 20 
> updates per second (this alone takes more CPU load than asterisk 
> /app_rpt + usb radio.
> 3. On this motherboard the USB controller and ethernet share a PCI 
> interuupt line and you cannot change it.
>     I've tried disabling the built on ethernet and still get the popping..
>     I've also flood and large pinged the machine which genreates huge 
> numbers of interrups from the ethernet chip and this has no effect on 
> the popping..
> 4. Tried other USB fobs with same chipset.
>     Created various types of heavy system activity to see if it has any 
> impact on the popping heavy disk use hevy network use and heavy vga use 
> (text mode)
>     moving interrupts  (changing them) on the motherboard.. getting usb 
> controller onto a different interuupt (ethernet ends up on same).
> 5. Measured and scoped 5V output on USB to be sure 'popping' sound is 
> not coming from 5V power supply.
> 6. Am really looking to hear what some others experience has been with 
> this..
>     what works and what does not?
>     The popping very much sounds like an interrupt issue or some kind of 
> issue where the task of sending and audio stream is completely dropped 
> for something else
> and then resumed leaving lots of holes heard as pops in the output stream.

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