Hi,
> OK I understand that. But is there any solution which permits to reset that > growing propagation delay ? How to reset the flowgraph buffers without > killing the application and restart it ? Is there any method that permits to > purge and resync buffers of the flowgraph ? The USRP supports timestamps for RX and TX. So you get tags for when data was received / is supposed to be transmitted. Using a custom block to modify the RX tags into TX tags ( to change the RX timestamps to TX timestamps a bit into the future ), you should be able to achieve a constant controlled latency. Cheers, Sylvain