[Discuss-gnuradio] packet encoder/decoder input-output rate

[Francois Quitin]

Dear all,

 

We’ve been working on a problem with gnuradio and we just can’t get it solved, so we might need some help. We have a transmitter that sends some waveform the the receiver, the receiver makes some computation, and we want the receiver to send some feedback information to the transmitter. The rate of the feedback link can be very low (down to 20 Hz), while the rest of the tx-rx chain works at 2MHz.

 

For the feedback link, we used packet encoder -> DPSK mod -> USRP at the Rx node, and USRP -> DPSK demod -> packet decoder at the Tx node. The USRPs work at a sampling rate of 2MHz.

 

Can someone help us to determine the sample rate of the information that enters the packet encoder so that it matches the 2MHz sample rate of the USRP at the output of the DPSK modulator? Since the packet encoder adds some overhead and CRC, we’re not sure how to adapt the sample rate of our feedback link without having samples piling up somewhere.

 

Does the packet encoder needs to continuously have samples at its input to generate a packet? Or can we send information to the packet encoder at very low rate, and the packet encoder will just generate one packet and sleep again until the next information comes in?

 

Thanks you for your help!

 

Francois