Re: [Discuss-gnuradio] USRP-Overrun Problem

[Andrea Montefusco]

Eder Matthias wrote:

> Well, as I unterstand, the main problem is, that the audio sink has got another clock than USRP has. That means that packets are lost, whan the audio sink buffer is full. 
> Ok so far, i can follow you. 
> But what can i do to solve this problem.
> The best way would be to synchronise the two clocks. But how can this be done? 

This is a well known problem in the HAM radio world as well.
In some hardware (QS1R, HPSDR) the problem was solved adding a D/A converter clocked by a clock 
taken from the A/D, therefore removing the needs of a PC audio card.

In a more general way, because, usually, the clock synchronization in hardware is not easily 
feasible, you need to use a software resampler.
However, due to the drift between the two clocks, in order to avoid slips, the scaling factor has to 
be dynamically changed.

The only software (with source available), at least the only I am aware of, to implement this 
adaptive resampler is WinRad (http://www.sdrham.com/winrad/download_source.html) written by Alberto 
I2PHD.


        *am*

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Andrea Montefusco iw0hdv        http://www.montefusco.com
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