Cospas-Sarsat 406 MHz distress beacons are provided in models which transmit either a “short” distress message or a “long” distress message as indicated below. 406-MHz beacon messages are comprised of:
- a message preamble which is the combination of the 160 ms of unmodulated carrier, the bit synchronization pattern and the frame synchronization pattern,
- various other data fields which provide a unique beacon identification and, depending on the protocol used, other information that would be useful to Search and Rescue Authorities.
Note that additional information describing the beacon message characteristics of the fields is provided by clicking on the appropriate section of the message format diagrams below, or via the menu on the right-hand column of this page.
Fields of the Short Message Format