I hadn’t anticipated moving up into the GHz range with this cheap little gadget yet but as it turns out, receiving and decoding the pulse trains that make up ADS-B is even simpler than using it to explore VHF/UHF.
This is entirely due to the excellent software available for this purpose.
These dongles are not plug-n-play and there are numerous ways to configure them – all this added to initial confusion in my case as a lot of disparate software had to be downloaded to make everything work. After that learning curve, ADS-B was simple.
ADS-B is far more common among European hobbyists than it is with us here in the States due mainly to the fact that is has been in use there longer. In a nutshell, ADS-B (Automatic Dependent Surveillance – Broadcast) is the name given to the system by which commercial (and some private) aircraft transmit their GPS coordinates to each other and to air traffic controllers on 978 MHz and 1090 MHz. This allows them to be seen, plotted and directed by ATC independently of radar.
This means that air traffic control can have highly accurate aircraft positions in places where radar wouldn’t be feasible – here in Houston, that initially meant helo flights to the Gulf of Mexico to and from off-shore oil rigs, but now it’s gone mainstream.
These latest SDR dongles are the first to have the speed and resolution to be able to decode ADS-B pulses. These pulses contain an aircraft’s GPS position, ID, altitude and speed with this info being transmitted once per second. Every 5th transmission from an aircraft contains additional data (tail number, squawk code, etc). Continue reading 'Receiving ADS-B on the SDR dongle'»