Re: [Discuss-gnuradio] Underrun in usrp causes corrupted packages

[Josh Blum]

On 10/10/2012 12:21 PM, Pär Särnblad wrote:
> Hi
> 
> I've been messing around with the benchmark rx and rx examples to make
> digital voice communication using codec2. I am using a message queue
> between the audio rx - codec path and the main loop that is adding packet
> number and callsigns to the package before sending it on to the tx path.
> 
> All works well until I uses a transmission rate higher than then audiopath
> generates because the usrp gets a underrun, and that is expected. What I
> didn't expect is that the packages that are sent is corrupted when there is
> a underrun.Is this due to problems with not pushing data through the usrp
> and things gets stalled there? The package block is padding for usrp .
> Should I use the eof flag? How do I solve this problem?
> 

In general, there should be some padding and and EOB tag at the end your
packet/burst to flush it through the DUC chain and to tell the DUC chain
that there will be no more samples.

> What I want to do is have a queue with different packages and be able to
> mix voice and data transmissions.
> 
> Also, the codec2 block is really outdated but have a working build of the
> current version and I will submit that when I have tested things out and
> fixed a block or blocks to handle different bitrates.
> 

I highly recommend that you take a look at the pre-cog project. Its
specifically aimed at solving problems like this. You should be able to
channelize different data sources through the simple MAC layer.

https://github.com/buoyboy/pre-cog/wiki

-josh