All,

I am trying to use both transceivers to transmit and receive data, which is
fine with the current GNU Radio blocks.  On one of the transceivers I am
currently using an independent piece of software to do a rough TDMA type
waveform.  Basically, the GNU Radio flow graph for one side looks like:

SIDEA
usrp_source_c       => deinterleave => multiply_const_cc =>
file_descriptor_sink
usrp_sink_c           <=  interleave    <=  multiply_const_cc <=
file_descriptor_source

SIDEB
(same source /deinterleave as above) => FM demod
(same sink / inteleave as above)         <=  FM mod


When I am running the TDMA code (connected through TCP sockets), the USRP
underruns (uU) when no data is sent.  That's no big deal when I have one
transceiver, but when I am running with two transceivers this REALLY messes
with things because of the interleaving.  What I have tried to do is patch
the file_descriptor_source by checking the socket for data (with a select()
call with a timeout of 0) and then sending noutput_items complex zeros to
the USRP to allow the data to be interleaved.  I still seem to be having
problems with underruns.  I know that mblocks will solve my problems in this
area, but I need a solution in a couple of weeks.  Should I throw my hands
up and wait?  or do I need to make my own scheduler?  gr_buffer?  HELP!

Thanks for any guidance,

David
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