Well this is a little off topic with respect to amateur radio. It does, however, involve a radio transmitter and receiver. I’ve been busy working with Jared on one of his 4H projects. I think I’ve mentioned before that he’s doing model rockets, r/c airplanes, and geology. We have the airplane about 75% done right now. I thought that some of you might be interested in the radio setup being used in today’s r/c world. It isn’t like the old days when my brother had r/c planes. I think they were on or near the 6m ham band. They had several channels and you’d have to put a tag on the aerial of the transmitter to let everyone know what channel you were on. Big problems if two people on the same channel both powered up at the same time!
Today everyone uses new stuff. Jared’s transmitter is 2.4 ghz with spread-spectrum and random frequency hopping. You can literally power up around 200+ transmitters at the same time and the chance of any of them getting on the same frequency scheme is nearly impossible. Pretty cool stuff! I believe the military may have been the first to start using this technology. There are some hams experimenting with it also but I’m not sure at what level. I think it’s mainly a UHF-only prospect due to the amount of bandwidth required to do it.
The company that makes the radios we’re using is called Spektrum. They have a pretty nice website with some info on how digital spread-spectrum works. Here’s a nice video from their website that shows them flying various helicopters and planes at the same time as turning on 100 transmitters. There is also a pretty nice shot of the spectrum analyzer display that shows how full the band is with signals. No crashes. I really enjoyed the video regardless of the fact they’re really using as a advertisement for their DSMX products.