PS - The decoder I built was tested with live recordings of a stensat beacon from the phonesat group, so I think it will certainly work in your case - if only with minor modifications.
-John On Wed, Jun 6, 2012 at 4:18 PM, John Malsbury <john.malsb...@ettus.com>wrote: > Adam, > > I apologize if I'm misunderstanding your question. But the packet decoder > in GNU Radio is not an AX.25, just a general purpose decode. I've hacked > together an AX.25 receiver with the N200. I can send the files to you > tomorrow. > > -John > > > > On Wed, Jun 6, 2012 at 3:52 PM, Adam Gunderson < > agunder...@ssel.montana.edu> wrote: > >> Hello, >> >> We are currently trying to setup a ground station for GMSK modulated AX25 >> packets at 9600 and 19200. >> >> Our current setup that works is the USRP N200 through GNU radio audio >> sink and to a Kantronics 9612+ TNC (gmsk_demod.png, quadrature demod -> >> audio sink). What we want to do is replace the hardware TNC with GNU radio >> packet decoding blocks and send the packets over TCP. >> >> We first tested the loopback through all the gmsk mod/demod and packet >> encoder/decoder blocks, (gmsk_loopback.png) and this works fine. >> >> However, when we send our received AX.25 packets through GMSK demod -> >> packet decoder -> TCP sink (gmsk_demod.png) we do not see anything on the >> TCP server side, which tested fine in loopback. >> >> We are assuming the hangup is in the packet decoder block as it is not >> recognizing AX.25 packets or possibly at the end of the GMSK demod block. >> >> Do we need to look into writing our own packet decoder block? If we need >> to do this, is there a good guide on how to edit existing blocks, or look >> at their work() functions? >> >> Do we need to also implement a derandomizer block before we even can >> start making sense of the bit stream? >> >> If we were able to get a byte stream with the framed AX.25 packets as an >> output from GNU radio to our TCP server we can deframe them there instead >> of in GNU radio, but we cannot get any output with this current setup. >> >> We have also looked at trying to get the GMSK Spacecraft Groundstation >> project to work but the versions must be out to date because the files >> located on https://www.cgran.org/wiki/GMSKSpacecraftGroundstation won't >> make. >> >> Thanks >> >> -Adam >> >> -- >> Adam K. Gunderson >> Space Science and Engineering Lab >> Montana State University >> agunder...@ssel.montana.edu >> >> <agunder...@ssel.montana.edu> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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