Oznog said:
Of course, being an aircraft you want to accomodate the situation where you lose signal for a second, possibly in a radical maneuver which are somewhat more likely to cause it. It may not be ideal to retain the last control settings received for a prolonged period but rather return to some settings which would be the best guess for neutral flight until the link is restored. Yet you would not want to do this with just a single pkt lost.
I hadn't notice this was for an aircraft?.
Have you considered the legal implications?, as far as I'm aware you require a specific type of equipment, on a specific frequency band, for aircraft remote control - obviously country dependent, but the UK is very strict over this (for obvious safety reasons).
But as far as the actual control goes (ignoring legal questions), the amount of data required is fairly small. Have you considered how a normal radio control system functions?, you could even duplicate that quite simply - it just sends varying width pulses.
Or if you want a proper digital system, send the data in packets (which again is similar to how normal radio control works). For example, you could send a four byte packet, rudder, throttle, ailerons, flaps, THEN a largish gap (to allow syncronisation). You then repeatedly send the same information - if your controls change, then the data changes, but regardless the transmitter sends the four bytes, followed by a gap, continually.
You might also send a fifth 'checksum' byte for error correction, this can be checked at the receiver, and the data rejected if incorrect - you could implement a scheme where if a certain number of errors occur in a row (say ten?) the aircraft enters a 'safety mode', throttle down and controls set for a slow circle and descent. The same should happen if the signal is lost completely - if you miss a certain number of packets in a row completely, again enter 'safety mode'.