I got back yesterday afternoon from three weeks in Wichita, doing CSeries flight testing.

While I was in Wichita, I bought the parts to cobble together a cheap open-source ADS-B In receiver (part 2), based on a Raspberry Pi computer and two software defined radios. ADS-B In is widely used in the US to transmit weather info and traffic to suitably equipped aircraft. It would be quite useful when flying in US airspace, and possibly useful when in Canadian airspace (see ADS-B Primer).

Today I took the ADS-B receiver flying, to see how it worked. The receiver I assembled emulates the popular Appareo Stratus ADS-B receiver, so it is compatible with any device that can receive signals from such a receiver. I used ForeFlight on my iPad mini to receive and display the data.

It was receiving transmissions from high flying aircraft on 1090 MHz when I fired it up on the ground. The cyan diamond represents the aircraft that was being received, and “+405” above the diamond means the aircraft was 40,500 ft higher than my aircraft, or 41,000 ft above sea level (Smiths Falls is just over 400 ft elevation).

I zoomed in on the traffic awhile later, and saw the call sign below the diamond (“WJA518”, or West Jet 518).

Level at 7500 ft, I was picking up signals from two ground stations. The ground station locations are shown the map with a while tower symbol.

The system had local and national radar and weather reports and forecasts for US airports.

There wasn’t any data for Canadian airports, but there were weather reports for numerous non-aviation reporting stations in Canada.

I had tested the system in Kansas, using the ground station at Newton, and it was receiving forecasts for Canadian airports. I’m not sure what the transmission interval is for the various data types. Maybe the Canadian forecast data would have arrived if I waited longer. In any event, airport weather reports are much more important than weather forecasts, and I saw no sign of those on either of these two tests.

If I was only flying in the US, it would be a no-brainer to stop spending $60/month on XM, but ADS-B probably isn't good enough to replace XM in Canada, as it has no Canadian radar data, and precious little other weather data. I'll use both ADS-B and XM Weather next summer, and then decide if ADS-B is good enough to stop subscribing to XM.