A modified ethernet packet structure might serve your needs. It has, as Michael suggests, a "lead-in" or "sync" field, followed by a start of frame delimiter that tells the receiver that the "lead-in" string has ended, thereby indicating the byte framing, then it presents source and destination address information, which, of course, you're at liberty to modify, and then the data, followed by a CRC. That same structure should allow your receiver MCU acquire bit and byte synchronization so it can properly interpret what it receives. The process will probably require that you modulate the transmitted data with its bit clock so that the receiver will be able to acquire timing and bit/byte synchronization. Manchester encoding is very simple, done in hardware, and, if the data rate is low, can be done in firmware. If Manchester encoding limits your bandwidth too much due to RF channel-width limitations, you can use MFM, which is, essentially, Manchester-code divided by two.

You can, of course, use asynchronous format, but that will limit your effective throughput considerably because you may have to transmit sync information with each byte.

Ome more thing ... Manchester encoding is, essentially, BPSK.

RE