Living on the East Coast, not far from New Jersey, it’s hard to escape the “buzz” around drone sightings lately. Some of these reports have even cropped up in my home state of Connecticut. While many of these sightings turn out to be ordinary aircraft, some stand out as worth investigating. It got me thinking about how to discern whether what’s flying overhead is an aircraft or something else entirely—and how to share those findings.
I found for low flying aircraft, flight tracking websites may not be picking up an airplane’s transponder. So we’re going to make our own receiver. See more in my latest video.
Last week, after dropping my kids off at swim practice, I spotted something unusual in the sky. It had a peculiar configuration of lights, including FAA-standard red and green lights, but also bright, non-strobing lights at the wingtips. Despite rolling down my car window to listen for any familiar sounds, like a helicopter’s rotor, the object remained unusually quiet. I captured what I could on my car’s Tesla camera, but the bright lights made it difficult to make out the structure. Intrigued, I turned to ADS-B Exchange, a flight-tracking website that aggregates aircraft transponder data. To my surprise, nothing showed up for the time and place of the sighting.
After consulting with my flight instructor—I’m in the early stages of earning my pilot’s license—I learned that aircraft flying too low might not be picked up by the ground stations feeding data to these websites. Enter software-defined radio (SDR), a tool that combines aviation and radio interests into one accessible gadget.
The RTL-SDR, a small USB device with an antenna connection, became the centerpiece of my experiment. Using an Android phone, a portable antenna, and free software like Dump1090, I created a mobile plane-tracking system. The RTL-SDR can pick up signals from ADS-B transponders, which broadcast telemetry data like identification, altitude, and speed. This data is vital for air traffic control and situational awareness among pilots. However, it’s not foolproof; ADS-B in most airspace is optional.
Setting up the SDR system was straightforward. With a simple USB adapter, I connected the radio to my phone, launched the necessary apps, and began receiving data. From my second-floor window, I tracked aircraft in real time, observing everything from small private planes to airliners. The setup proved effective at capturing data directly from transponders, even when websites like ADS-B Exchange or FlightRadar24 showed gaps.
For those interested in a more permanent solution, desktop setups using tools like Virtual Radar and a Raspberry Pi are excellent options. Additionally, in the U.S., some aircraft broadcast on a secondary frequency, 978 MHz, so using two radios to cover both bands ensures comprehensive tracking.
What stood out to me during this process was how accessible this technology has become. With just a phone and an SDR, anyone can explore what’s flying overhead, filling in the gaps left by online trackers.