The First 2.4GHz Aircraft Radio

It’s hard to believe, but all the RC aircraft radios we now use and love got their start only 12 years ago. First reviewed in our March 2006 issue, the first airplane radio operating with a 2.4GHz modulation was the DX6 from Spektrum. In development for several years, Spektrum’s optimized DSM system used direct sequence spread spectrum (DSSS) technology, which had been well proven with competitive RC car racing. Unlike the then-current 27MHz and 75MHz narrowband systems, DSSS generated a wideband signal on a single frequency, and the signal information was encoded with a globally unique identification (GUID) number so that the receiver could recognize only the information sent from its specific transmitter. With more than 4.2 billion GUID codes available, it was—and still is—virtually impossible for the receiver to be affected by anything other than its specifically mated transmitter.

We were amazed by the Spektrum DSM system as it operated in the ultra-high 2.4GHz band and offered several advantages over previous systems. Typical radio interference that is generated by electric motors, speed controls, and metal-to-metal noise is below the 300MHz range, and with the new Spektrum radio transmitting 2.4GHz (2,400MHz), its frequency range was—and still is—eight times higher than any modelgenerated radio-frequency noise. The radio couldn’t “see” the noise, so it was immune to that interference. The DSM system also isolated the receiver from other outside high-frequency interference sources, such as cell phones, pagers, and wireless computer systems.

The many features included with the Spektrum DX6 were also cutting edge for the time, and it led the way for many of the now-wellknown and popular radio systems that carry the Spektrum brand name today.