Re: [Alsa-user] Spikes when recording

2011-05-21 Thread Bill Unruh
Of course it could be that some other program is trying ( and failing) to get a hold of the sound card at that time but disturbing the system in theprocess. So to be clear you have some external device (radio, amplifier, whatever) feeding and audio signal to your sound card. YOu have a program whic

Re: [Alsa-user] Spikes when recording

2011-05-21 Thread lists
I would first remove the audio source then short the inputs to the soundcard, run it overnight, and see if the spikes appear. That would determine if the spikes are in the source itself or somehow created in the PC. Most people don't do automatic updates on their linux boxes, but by chance do

Re: [Alsa-user] Spikes when recording

2011-05-21 Thread Tom Jewell
It's conceivable that it's the UPS itself that performs some chore at the same time everyday. You could try plugging into the mains (without UPS) during that period of time and see if the problem goes away. Otherwise, I agree that it could be some sort of once-a-day RFI that may be difficult t

Re: [Alsa-user] Spikes when recording

2011-05-21 Thread Peter Hoffmann
Hi, The computer is on a UPS. The image is just cutout from a whole hour. I'm recording 24 x 1 hour per day. 23 hours are fine without spikes, but at always the same time at 2:30 such spikes occur. Kind Regards, Peter On Fri, May 20, 2011 at 5:22 PM, James Shatto wrote: > That seems pretty re