Recently I was asked about reading multiple PPM encoded signal streams, merging their data with other signals, and generating new PPM outputs.  I've writing a new PulsePosition library, which is in need of beta testers.

The PulsePosition library is designed to be able to simultaneously input and/or output up to 8 PPM encoded streams, each with up to 16 signals.

PulsePosition is designed for 0.02 µs accuracy (approx 24X better than most Arduino implementations using AVR Timer1) with tolerance for significant interrupt latency caused by other libraries.  Pin change interrupts, which add error due to interrupt latency, are never used.  All pulse input and output is done directly with the 48 MHz clocked timer hardware.

http://www.pjrc.com/teensy/td_libs_PulsePosition.html

At this early stage, pretty much all testing had been done only with verification of signals on an oscilloscope.

I'm hoping to find people who might be interested in testing this with real signals and real applications.