In researching the requirements for a quadcopter I found that I needed a real RC hobby radio. I’ve looked into these in the past and was always daunted by the price of the radios used traditionally such as those by Futaba and Airtronics. But, given that I was going to be really getting into these copters I decided to go ahead and spring for a good one. I started looking around at what others have used and ran across several. First, the ones I mentioned are still in use, but they’ve moved away from the 75MHz band and analog signaling they have used for years and instead started using 2.4GHz. And not just that, they now sport spread spectrum, frequency hopping, and digital signals which all adds up to a highly reliable radio solution with tremendous range. Even the most basic radios have a range of 1.5Km which I find totally amazing.
With that knowledge in mind, I started looking at the various options. There is a good 8-channel setup from Futaba, and the same from Airtronics. Lots of people like Spektrum and Hitec as well and generally they are pretty similar in terms of feature set. They all come in at about $300 and include features such as multi-model memory, touch-screen displays with telemetry, and SD-card slots. But then I stumbled across what is almost an open source radio. The Turnigy 9XR is an Arduino-based radio using low-cost parts shared with cell phones that are really inexpensive. This results in a radio platform that costs $50 and takes a JR-style TX/RX module (those are the pieces that actually do the broadcasting and reception.) It doesn’t have a touch-screen display, but otherwise it is pretty similar in terms of features as the $300 models. This is the 3rd generation model and others find it works great. Given its Arduino roots and the ability to run an open source open9x firmware stack, I decided I had to give it a try. And hey, if it doesn’t work out, I can always switch to another brand and re-use the RX/TX module.
I purchased the Turnigy 9XR from hobbyking.com and the Frsky DJT transmitter and V8FR-II receiver for a total of $90. I’ll let everybody know how it works.