Re: [Discuss-gnuradio] Dropped Packets

[Eric Blossom]

On Tue, Feb 14, 2006 at 02:12:38PM -0500, Tom Rondeau wrote:
> I am currently developing a BPSK transceiver with a fully-functional PHY and
> MAC layer defined in the GNU Radio/USRP. Everything almost works perfectly
> (the code will be released on our website once this final problem is
> solved), but I cannot get the final packet to receive correctly. Even when
> using the GMSK2 example, it seems like the final packet always messes up.
> When I take a closer look at the transmissions using our signal analyzer, I
> notice that the transmitter does not finish transmitting the final signal
> (it sends the preamble (I put this into the packet_utils.py for my
> synchronization loops), the access code, and part of the payload).
> 
>  
> 
> The problem seems to come from the thread handling the transmit procedure
> shutting down the USRP before the packet can be fully transmitted.
> 
> Any ideas?
> 
> Thanks,
> Tom

I can think of two causes.  The one you mentioned, and the possibility
that the FPGA is turning off the transmitter before the last packet is
all the way out.

Are you testing using the Flex 400 board with set_auto_tr(True)?
Is it only the last packet that gets truncated?  Have you tried
transmitting packets discontinuously similar to the benchmark_gmsk_tx?
When using discontinuous transmission are the other packets OK?

A quick fix for your hypotheis goes something like this:

   ...
   fg.run()
   time.sleep(1)
   ...

Eric