----- Original Message -----
From: "Nick Foster" <address@hidden>
Sent: Saturday, October 23, 2010 9:52 PM
Subject: [Discuss-gnuradio] Gnuradio Mode S project released
> Hi all,
> I finally got around to cleaning up my Mode S receiver enough for
> release. The following is a short description of the software:
> The Gnuradio Mode S project implements a Mode S/ADS-B receiver. Mode S
> is the latest aircraft transponder technology, primarily used in
> commercial aircraft. Probably 30% of those aircraft currently broadcast
> their position via ADS-B (more in Europe, less in the US), which is a
> protocol that uses Mode S extended squitters as the transport layer. By
> 2020 all aircraft operating in controlled US airspace will be required
> to broadcast ADS-B.
> The receiver demodulates and decodes the 1090MHz PPM-modulated Mode S
> transmissions using industry-standard techniques to mitigate FRUIT
> (transmissions on top of one another) and correct multiple bit errors.
> Using a USRP with a DBSRX + LNA + SAW filter, ranges of 220 miles have
> been regularly seen. The WBX should allow similar ranges without the
> filter and LNA, although I haven't really tested WBX much. It is of
> course line-of-sight, making antenna site selection important.
> TL;DR: Follow airplanes around from 200 miles with your USRP.
> The receiver allows interfacing to a number of output formats,
> KML for Google Earth. Screenshots of the Google Earth interface can be
> found here:
> There is also a TCP port 30003 interface to use with PlanePlotter, a
> third-party application to view aircraft data. PlanePlotter isn't free,
> and I haven't tested it at all, so while it should work, YMMV. If you
> test it, let me know.
> There are definitely still bugs in it -- one thing that comes to mind
> that a very few aircraft seem to produce data which uses correct
> for position packets but which contains non-position data. This causes
> "impossible" aircraft positions. Luckily it seems to be pretty rare.
> Future developments for the receiver include implementation of
> multilateration using the VRT timestamps of USRP2. Multilateration
> allows the time-based triangulation of aircraft which use Mode S but
> which do not broadcast ADS-B. Three or more networked USRP2s should
> allow position determination to a reasonable degree of accuracy.
> Clone the Git repository to build the software with the usual
> bootstrap/configure/make/make install rigmarole; it should compile on
> anything you have Gnuradio installed on, although with a 4Msps data
> it does require a bit of CPU power. In order to use the KML output you
> will have to have libsqlite3 and python-sqlite installed, although
> those are Python dependencies it will still compile without them. I
> think that's it for the dependencies. Oh, it uses UHD, so you should
> finally get around to building UHD and gr-uhd to use this software.
> git clone git://github.com/bistromath/gr-air-modes.git
> There is also a CGRAN page with corresponding SVN repo, which is a
> mirror of the Github repo:
> The Python executable is src/python/uhd_modes.py.
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