Unexplained aerial phenomena enthusiasts gathering together in the UAP Tracking Network (UAPTN) have turned to software-defined radios, not as a means to find aliens but as a means of discounting commercial aircraft from their recordings.
"We want to allow those without deep pockets to make meaningful contributions to the data we hope to gather," writes UAPTN's Bob McGwier. "So how do you think you would respond to a recommendation that we ask you to buy a several thousand dollar camera in order to prevent you from recording a jet airliner? We want to work towards enabling much less expensive cameras contribute video plus other data in our system.
"Let’s discuss an obvious first step. How can you prevent capture, by accident, overflights by commercial airplanes, or general aviation? For now, let’s concentrate on commercial flights. Flightaware provides detailed maps with moving icons for tracking flights. They have taken on the job of allowing individuals with interest provide them with data to aid in their primary job.
"They designed an inexpensive receiver," McGwier continues, "you plug into a USB port on a Raspberry Pi or other small board Arm-based computer. They spent resources constructing a codebase to allow this system to be used for tracking commercial and government planes operating in a normal manner.
"[The] FlightAware Pro Stick plugs into the USB port on the computer we will use in our data trackers. This will be our recommendation for the basic tracker to eliminate many airplanes. This will get more complex, costing another few dollars to add the necessary extra pieces to eliminate most general aviation airplanes, but for now this is the 90% solution."
Costing $20, the FlightAware Pro Stick is an RTL-SDR software-defined radio receiver which is capable of tuning into and recording the ADS-B signals sent from commercial aircraft. "Most commercial flight tracking sites censor military and private jets," RTL-SDR.com explains of the need to receive the data yourself, though adds: "However, of course a military aircraft conducting operations are always able to turn ADS-B off if required for the mission which is what the UAP network will probably detect the most."
The discussion on using the FlightAware Pro Stick for discounting commercial flights in UAP monitoring can be found on the UAPTN Forum.