While we're talking about new decoders, is anybody currently working on ADS-B on UAT 978MHz? As far as general aviation goes, this is where all the good stuff (weather, GA transponders, etc) is going to be.
The commercial receivers cost like $900 and I don't see why. I'm just coming up the RF and demodulation learning curve, but I could take a stab at it. I would be more inclined to do so if someone who really knew what he was doing thought it was worth attempting. There's some stuff here: http://www.ads-b.com/PDF/UAT%20SARP.pdf that describes the RF format. I can't tell if bandwidth is going to be a problem. The spec requires 20dB attenuation beyond 1 MHz and 50 dB by 2 MHz, making me thing this is perhaps within the dongle's capability, or will the small amount of energy outside 2 or 3 MHz is actually important. See... just coming up the learning curve. I think there is coverage in my area (San Francisco, CA) so I can make recordings in the air if that's a help. One problem with these aviation signals is that they are general hard to record on the ground. Regards, Dave J On Fri, Dec 6, 2013 at 9:33 AM, <[email protected]>wrote: > Send osmocom-sdr mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.osmocom.org/cgi-bin/mailman/listinfo/osmocom-sdr > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of osmocom-sdr digest..." > > > Today's Topics: > > 1. Re: Need help decoding of FLARM (868.2/868.4MHz) (Nick Foster) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 6 Dec 2013 09:33:39 -0800 > From: Nick Foster <[email protected]> > To: Fritz Meier <[email protected]> > Cc: sdrrtl <[email protected]> > Subject: Re: Need help decoding of FLARM (868.2/868.4MHz) > Message-ID: > < > ca+jmmq_fozso+afy-4bktan_gnt9aspt1k2mbcgerrw2znl...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > OK, turns out someone beat us to it a while ago, even going so far as to > reverse-engineer the cheesy crypto FLARM put in there to discourage > copycats. The PHY is a Nordic nRF905 (+10dBm output), the medium access > control is blind random-interval squitter with no two-way communication, > and all Onera's vaunted "prediction" logic is being done in an AVR (!). > Kids these days... > > http://pastebin.com/8ke6jnQZ > > The good news is Manchester-encoded GFSK is dead simple to decode, and the > known parameters of the nRF905 make it easy to write a receiver. > > --n > > > On Fri, Dec 6, 2013 at 8:14 AM, Nick Foster <[email protected]> wrote: > > > This is a new one! Thanks for bringing it to my attention. Looks like a > > voluntary, GPS-based (i.e., not secondary surveillance) system. While the > > serial protocol appears to be NMEA-like, the protocol "under the hood" at > > the PHY layer could be basically anything, and the FLARM consortium > appears > > to have elected to keep specs hidden. Reading the dataport specification > > gives few insights as to the PHY layer, but at least it's good to know > the > > protocol has "future-proof" support for all aircraft types. > > > > [image: Inline image 1] > > > > If you record good FLARM transmissions I am happy to assist in decoding > > what I can, not least because proprietary protocols were meant to be > open. > > =) > > > > --n > > > > > > On Fri, Dec 6, 2013 at 7:58 AM, Fritz Meier <[email protected]> > wrote: > > > >> Hi, to all > >> after I've seen with RTL ADSB and DUMP1090 how ADS-B transponder data > >> 1090MHz (pulse modulation) is decoded I would like to start with FLARM > >> (Europe 868.2 and 868.4MHz frequency modulated). The position data of > >> gliders > >> (ID, latitude, longitude and altitude) are sent 1xsec in the form of > >> NMEA-like records. > >> I work with the BeagleBone black and have a FLARM transmitter installed > >> near > >> the RTL-Dongle/Antenne and may at any time start recording I/Qsamples > >> with RTL_SDR. > >> Thanks > >> Fritz > >> > >> > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.osmocom.org/pipermail/osmocom-sdr/attachments/20131206/c495a45d/attachment.html > > > -------------- next part -------------- > A non-text attachment was scrubbed... > Name: image.png > Type: image/png > Size: 32534 bytes > Desc: not available > URL: < > http://lists.osmocom.org/pipermail/osmocom-sdr/attachments/20131206/c495a45d/attachment.png > > > > ------------------------------ > > _______________________________________________ > osmocom-sdr mailing list > [email protected] > http://lists.osmocom.org/cgi-bin/mailman/listinfo/osmocom-sdr > > > End of osmocom-sdr Digest, Vol 25, Issue 7 > ****************************************** >
