Re: [Discuss-gnuradio] question about overruns with simple flowgraph

[Marcus D. Leech]

On 08/08/2013 12:03 PM, Vanush Vaswani wrote:
> Has there been any effort in using PTP to solve the two-clock problem 
> (like Audinate's Dante)?
The two-clock problem exists due to the fact that the two *hardware* 
clocks involved here -- the audio subsystem, and the USRP aren't
  locked to each other, and aren't at exactly, precisely, the rate you 
think they are (the nature of oscillators).

Clock-skew (between source and sink) tends to get "absorbed" in 
buffering, but since buffering is a finite resource, occasionally 
leading to the audio
  subsystem saying "guys, I can't accept any more samples at the 
moment, my buffers are full".  The way to "solve" this problem is to 
have a control-loop
  that allows you to fine-tune the rate that samples are delivered to 
the sink -- you need a "speed up a bit/slow down a bit" control message 
that occurs
  before things are about to get ugly.


--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org