Hexadecimal Representation of Beacon

406 MHz beacons are identified by the content of the message that they transmit. Within the Cospas-Sarsat System beacon message content is identified using the hexadecimal representation of the binary bits encoded in the beacon, and are presented in either a 15, 22 or 30 hexadecimal character representation.

15 Hexadecimal Identification

All 406 MHz beacons, regardless of message format (i.e. long or short) or protocol, should be coded so that the combination of bits 26 through 85 is unique. For beacons coded with variants of the Standard Location or National Location protocols, the 15 hexadecimal identification is calculated assuming the position bits in the first protected field of the message are set to their default values as specified in document C/S T.001 "Specification for Cospas-Sarsat 406 MHz Distress Beacons".

The hexadecimal representation of these bits is also unique and is referred to as the beacon 15 Hex ID. See the example below:

The 15 hexadecimal representation is the beacon identification commonly used in referring to a beacon, and is used operationally as the identification in Cospas-Sarsat distress alert messages sent to SAR services.

22 Hexadecimal Representation

Short format messages (bit 25 set to "0") are comprised of 112 bits. Since bits 1 through 24 are required for synchronizing the decode equipment, only bits 25 through 112 are available to be programmed with message content. The hexadecimal representation of bits 25 through 112 is referred to as the beacon 22 Hex representation.

30 Hexadecimal Representation

Long format messages (bit 25 set to "1") are comprised of 144 bits. Bits 1 through 24 are required for synchronizing the decode equipment, therefore, only bits 25 through 144 are available to be programmed with message content. The hexadecimal representation of bits 25 through 144 is referred to as the beacon 30 Hex representation.