On Sat, Mar 24, 2007 at 01:17:28PM -0400, Eric A. Cottrell wrote: > Hello, > > Yet another project I am interested in. Number 157 on the list. 8) > > ADS-B is an interesting system that allows aircraft to send position and > other information. It uses the 1090 MHz Transponder frequency. > http://www.garmin.com/aviation/adsb.html > > ADS-B is more progressed over in Europe. It is in a testing phase on > the East Coast of the US. It is out of range from my QTH. > http://www.garmin.com/aviation/Safe_Flight_21_v0.69a.pdf > The UAT is used for general aviation on a frequency of 978 MHz. > > I was interested in the SBS-1 which decodes Mode S and ADS-B. > http://www.kinetic-avionics.co.uk/sbs-1.php > > The design uses SDR techniques. It appears the decoding is done in a > Xilinx Spartan. http://www.tech-software.net/inside_sbs1.php > There are other interesting things on the website. > http://www.tech-software.net > > Some interesting info about the data being encrypted and delayed > 5 minutes over TCP/IP. So no direct Linux support. > http://www.kinetic-avionics.co.uk/forums/viewtopic.php?=&p=22004 > > I talked to someone with the SBS-1 and they said there is some ADS-B > activity as some US aircraft fleets have it installed. > > I thought that the USRP and DVB tuner board could also receive ADS-B and > Mode S. I did not know if my discone and long coax run would work. So > I did some experiments. > > I used the fft and oscilloscope programs to check for activity. I did > see activity on 1090 MHz. I then modified the oscilloscope program to > do AM detection with the gr.complex_to_mag() function. I saw various > pulse trains that look correct. There were some short ones that look > like old transponders and longer ones that look like Mode S. I found > the range of good gain settings was narrow (31 to 35) with 33 to be the > best. I found the decimation of 16 gave good pulse shapes. The pulse > timings are in 500 nS units so you need 250 nS sample times at least. > This is the data format. http://www.tech-software.net/adsb_decode1.php > > The next step is to write a decoder block that takes in the samples and > prints out type and raw data to the standard output.
This is great! Looking forward to what you come up with! Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
