Padding burtsy blocks

I have a flowgraph that I’m trying to develop in simulation first before
deploying to some sort of hardware like a USRP. The flowgraph begins
a ZMQ Pull Source and then I have all my signal processing blocks
afterwards (eventually there would be a UHD Sink). The ZMQ block only
produces samples when it receives a message so when it doesn’t receive
samples the flowgraph doesn’t run.

If the work function for any block is only called when there are samples
the input buffer I don’t see how adding any blocks after my ZMQ Pull
could help. So that leaves making my own ZMQ Pull Source that emits
when it has no other message. Do I have any other options? If I add a
this feature would be useful to merge back into GR or is this not really
intended use case for GR?


Hi Devin,

the “padding with zeros unless samples occur within a specific time” job
can be done with gr-eventstream [1] [2] , but:

If you’re going to use USRP sink anyway, what about using tagged stream
You could replace your “Pull Source” with a “Pull Message Source” ->
“PDU to tagged stream”->signal processing->“USRP Sink” (with “packet
length tag name” set accordingly)

Best regards,