Experiments with an extended asynchronous protocol

As a first stage in an investigation into improved serial data transmission, experiments have been carried out on an asynchronous system in which several frames are packaged into a “superframe”. The superframe contains message, synchronization and cyclic redundancy information. Simulations have shown that long superframes are better at low error rates, and short superframes at high rates. A cyclic redundancy check (CRC) of degree 14 gives very good security against undetected error. Alternative methods of start-bit detection had little effect. The system appears to be suitable as the basis of an adaptive method of communication, in which the superframe length and the CRC degree could be subject to closed-loop control.