Yeah I figured that was the main issue, an AX.25 encoder/decoder would be awesome!
Thanks -Adam On Wed, Jun 6, 2012 at 5:20 PM, John Malsbury <[email protected]>wrote: > 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 <[email protected]>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 < >> [email protected]> 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 >>> [email protected] >>> >>> <[email protected]> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> [email protected] >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >> > -- Adam K. Gunderson Space Science and Engineering Lab Montana State University [email protected] (406)-570-8711
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