I am NOT an FMA dealer, but a great fan of the product after owning FS5 and FS8 receivers. They work very well and as advertised. I am actually split in my preferences between PCM and PPM because of my positive experiences. I have taken the liberty of cutting and pasting a description of their Digital Signal Recognition technology from the website.

DSR stands for Digital Signature Recognition and is the latest technology for secure receiver decoding. Developed and implemented exclusively in FMA Flight System receiver products, DSR works with any standard FM transmitter, is affordable, and provides interference rejection far beyond any other method of decoding used in the R/C industry to date. On startup, Flight System receivers check for valid data. DSR locks on to your unique transmitter characteristics such as FM shift, channel count, pulse widths, and frame length. During flight, DSR compares the received data against stored DSR variables. If an anomoly is encoutered, DSR invokes 4 levels of error correction that can actually repair damaged data and re-construct frame information. This approach is only possible through the advancement of powerful microcomputers used in Flight System receivers. The method is faster and smarter than PCM or any other method for secure data decoding. In addition, all DSR based receivers from FMA support fully programmable failsafe on all channels. Failsafe is simple to setup and uses the controlling transmitter as an interface during the process. Enter failsafe setup mode by holding down the programming button as you apply receiver power. Move the transmitter channel you wish to program. Put the servo where you want it for failsafe condition and press the button again. That's all there is to it. You can read more about DSR technology by visiting the support section of the FMA Direct website and downloading the "FMA Flight System White Paper".