Radio Waves from a Height of 30,000 Feet Above Ground Level
Article Title: RDS Signal Reception During Flight: A High-Altitude Adventure
Flying at high altitudes can extend radio frequency (RF) signal reception range, thanks to improved line-of-sight visibility to transmitters, reduced ground clutter, and specialized antenna systems. This was proven during a recent flight by journalist Nick Langan, who used a portable radio to scan the FM band and positively identify several stations during his journey from Philadelphia to Las Vegas for the 2025 NAB Show.
While RDS (Radio Data System) signals are primarily intended for receivers near the surface, Langan was able to pick up RDS transmissions during his flight. The average distance of RDS receptions was around 142 miles, with the farthest reception coming from 93.1 KRVN(FM) in Lexington, Neb., at a distance of approximately 240 miles.
The TEF6688, the portable radio used by Langan, captures RDS PI codes quickly using firmware developed by Sjef Verhoeven and maintained at fmdx.org. A separate algorithm was developed for translators, causing their PI codes to begin with a "D" prefix.
Interestingly, many stations didn't seem to be running RDS, but the vast majority did, even in more sparsely populated regions. The vast majority of RDS receptions came from the north side of the aircraft.
Langan noted four separate translator stations over southern Colorado: 93.5 K228EV(FM) Montrose, 97.1 K246CC(FM) Delta, 101.9 K270AY(FM) Grand Junction, and 103.9 K280GQ(FM) Grand Junction.
However, it's important to note that the local oscillator of an FM receiver could potentially interfere with aircraft navigation frequencies. Therefore, it's crucial to ensure the use of such devices is permitted according to FAA rules.
Langan had a fantastic time at the NAB Show and looks forward to continuing to share new stories and features with their website team. He also looks forward to meeting readers again at next year's NAB Show.
Key factors that contribute to extending RF signal reception range during flight include antenna design and orientation, transmission power, use of signal boosters or repeaters, and reducing interference and obstructions. By understanding these factors, we can further improve RF signal reception during flight, including RDS signals.
References:
- https://www.fcc.gov/general/radio-frequency-spectrum
- https://www.faa.gov/air_traffic/publications/media/air_traffic_control_handbook_volume_1/media/Chapter%204-Radio%20Communications.pdf
- https://www.tef-electronics.com/products/tef6686/
- https://www.fmdx.org/
- https://www.researchgate.net/publication/319464592_A_Study_of_the_Effect_of_Height_on_Radio_Frequency_Signal_Reception_Range
- During his flight from Philadelphia to Las Vegas, journalist Nick Langan utilized technology like data-and-cloud-computing and portable radio to broadcast his journey, even picking up RDS (Radio Data System) signals at high altitudes.
- The reception range for RDS signals improved during Langan's flight, with the average distance being around 142 miles, and the farthest reception coming from a station in Nebraska, at roughly 240 miles.
- The TEF6688 portable radio, equipped with specialized media for data decoding, swiftly captured RDS PI codes during Langan's flight, including translator stations in southern Colorado.
- While many stations didn't seem to be running RDS during the flight, a vast majority did, even in sparsely populated regions, with the majority of receptions coming from the north side of the aircraft.
