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Sound drop-outs

Posted: Fri Jul 01, 2016 2:45 pm
by Ste

Does anyone else get sound dropouts when using SDRUno and greater than 5Mhz bandwidth?

Is there a solution to this? The issue seems to get worse when I zoom in on the waterfall.

CPU usage is only 20%/25% according to SDRUno and around 30% according to Windows.



Re: Sound drop-outs

Posted: Sat Jul 02, 2016 12:57 pm
by DanubeBCL
Yes, Stephen, I have the same or at least a similar problem.
For me the audio stuttering seems to be related to the "PERF" button. When the PERF button is on, audio is interrupted every 4 seconds for about 500 ms. When PERF is on, it is impossible to decode DRM radio because the audio is so much corrupted that Dream.exe never synchronizes. Deactivating PERF brings DRM radio back at once.
Moreover the PERF button shifts the passband the more you tune off center. You never "hit" a station which is shown close to the spectrum borders. As the center spike of SDRPlay distorts the audio you always have to tune "off center" to get a clear audio. But with the PERF button on things get worse and worse the more you are off center.
The selected spectrum bandwidth also seems to have an influence.

After playing around with all sorts settings to no avail I have decided to leave the bandwidth to 0,5 MHz, PERF button off. Of course I miss a lot of spectrum width doing this, but it is the only way to achieve the following:
No audio stuttering
DRM reception possible
Tuning off center possible

BTW: The PERF button only increases CPU usage from 4% to 5% on my PC: Thus a poor CPU cannot be the cause for the dropouts and audio issues.
73s, Heinrich

Re: Sound drop-outs

Posted: Sat Jul 02, 2016 10:13 pm
by Ste
Thanks for your reply Heinrich. I have also noticed the same with the PERF button although it doesn't seem to make as much of a difference for me.

I agree that I don't think the CPU is at fault but SDRUno isn't fully utilising the CPU available, I've been experimenting with making the SDRUno.exe process High Priority or Realtime priority but this needs more testing before I can say if this affects the drop-outs or not.

I've also tried sending the audio to a VAC but the dropouts still persist.


Re: Sound drop-outs

Posted: Sun Jul 03, 2016 8:09 am
by DanubeBCL
Ste wrote:I've also tried sending the audio to a VAC but the dropouts still persist.
I am using the "famous" ;) VB Audio Hi-Fi Cable for all my SDRs (Perseus, Winradio G33, Elad S2, Angelia, that SDR with the hash software as well ;) ...). This is my default system soundcard. It never gives me big trouble there. Only the VAC of OpenHPSDR PowerSDR is a bit peculiar and needs a little tweaking for digital radio DRM.
My problems with SDRuno and SDRPlay RSP are definitely reproducable with the PERF button. The PERF button makes the audio stream almost unusable. It makes it totally unusable for DRM with Dream.exe.
Maybe someone can fix this sooner or later.
73, Heinrich