[SATLUG] [OT] Cell phone rant / open source idea

[Geoff]

Brad Knowles wrote:
> USB is actually pretty bad for latency to begin with, even when the 
> devices are native.  Simulated serial over USB plays real hell with 
> latency, and for example makes trying to do NTP to a refclock pretty 
> much useless.  I can't imagine that the situation would be much 
> different for VOIP over simulated serial over USB.

Know of a guy in Oklahoma that was using a USB "professional" sound card 
(multi-XLR in/outputs).  He was using the sound device on his computer, 
setup to accept SpeakFreely connections, to remotely key and send audio 
to his ham radio transmitter, when he was on the road, using VoIP.

After many tests, the latency would increase to 16 seconds, and hold 
there... packets would skip, audio was 'skipping'... took out the USB 
'pro' audio setup, and used a generic 24-bit PCI sound card, with a 
transformer from balanced to unbalanced, and his latency problems went away.

I never knew the 'exact' reason (until now) but always suspected it was 
the USB thing.

--
-Geoff