RTLSDR decoding of ADS-B signals…

June 26, 2013 | Amateur Radio, Radio Controlled Airplanes, Software | By: Mark VandeWettering

A few days ago, I wrote about the EZCAP EZTV645 dongle that I got which could be used with RTLSDR software to implement asoftware defined radio that only cost $20. I also had ordered a NooElec radio (similar, but with the R820T tuner that most people seem to favor) as well as an MCX-SMA adapter pigtail so I could use it with my mag mount dual band hamradio antenna that I have.

Today, for kicks, I drug it outside, hooked it up, and then started playing with it. Unlike my earlier tests, I could see some traces of a signal around the 1090Mhz ADS-B frequency, so I download ADBS# from here and fired it up. It immediately began detecting packets, so I went ahead and downloaded ADSBSCOPE from here, configured it to accept local data from the ADBS# server, and voila! It worked! Here are a couple of screen caps from a few minutes of sitting around outside at lunch:

adbs

adbs2

Ironically, I didn’t see a huge difference in difference between using my mag mount antenna and the cheap antenna that comes with the dongle, but neither are optimized for the 1090Mhz frequency either, so perhaps that’s not any kind of meaningful test. I think I am going to try to build a stacked colinear antenna that is, and we’ll then do some range testing. But at least close to the OAK airport, I can definitely get some good signals.

More later.

Comments

Comment from Gary Mastenbrook N8DMT
Time 6/26/2013 at 5:03 pm

Nice write-up on the ADS-B functionality! Don’t forget about the zenith hole on those colinear antennas. Generally it’s a good trade for gain at the horizon, but if the zenith hole is too deep, then you’ll lose overhead reports (even with the much shorter range.

Comment from Mark VandeWettering
Time 6/27/2013 at 11:10 am

I’m aware of the hole, but don’t think it will be too serious. The higher the azimuth gets, the less time the plane actually spends at that azimuth, so any drop outs will be of short duration. And, of course since my interest in this is purely for fun’s sake, there is no real downside to drop outs.