On Tue, Apr 8, 2014 at 1:42 PM, Ken Adams <[email protected]> wrote: > I'm looking for some tips on how to improve file transfer using two > USRP's. I understand the method I'm using might be fairly crude, but I'm > just starting out. > > Problem is I'm dropping a lot of data out of the file (receiving missing > parts of a string and such). This gets really bad when one of the USRP's is > moving. > > File Source > Packet Encoder > GMSK Mod > USRPB100 Sink > > USRP B100 Source > Xlating FIR Filter (LP 100khz) > GMSK Demod > Packet > Decoder > File Sink. > > I want to try and add some FEC, however, the only FEC blocks that ship > with GNURadio say "This package is for continuous data, not packetized". > Any FEC tips would be nice. > > Is there anything wrong/bad with this flow graph for sending files? Or > perhaps a better solution? I understand there could be a heap of problems > not relating to GNURadio, but I'm sending the files in the middle of a very > large (>1mile square) open field , with good line of sight. > > Cheers, > > Ken >
Ken, There's lots that can go wrong between the transmitter and receiver. As you've already identified, there's no FEC here, so nothing to fix an error. Even a single bit error in a packet will cause you to lose that packet because of the CRC check. At our latest hackfest, we worked (among other things) on two things: our new FEC system and gr-mac. The FEC API system will allow you to apply FECs to packetized data, and gr-mac has ARQ. See the notes from the event for where things are: http://gnuradio.org/redmine/projects/gnuradio/wiki/Hackfest1403-2 Tom
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