Y1-03-0233 Rev. L
6
STEP TWO - HOW THE BEACON WORKS
1.
How your beacon brings help
406 MHz beacons are a type of portable emergency equipment that
transmits a distress signal to search and rescue (SAR) organizations.
The purpose of these beacons is to aid SAR teams in tracking and
locating ships or individuals in jeopardy as rapidly as possible.
The 406 MHz frequency is a worldwide dedicated emergency frequency
that is detected by a special system of satellites called the Cospas-
Sarsat system. This satellite system was established by, and continues
to be supported by, its primary benefactors - the USA, Russia, Canada
and France. The Cospas-Sarsat system has saved over 23,500 lives -
and counting - since its inception. See Appendix G or the Cospas-Sarsat
website for more information about the system at
www.cospas-
sarsat.org.
When a 406 MHz beacon is activated, the digital distress message is
sent to Cospas-Sarsat satellites and, in turn, the distress message is
relayed to SAR. The distress message contains important information
about the beacon and its owner. Additional information about the beacon
is accessed by SAR from the beacon registration database. At the same
time the 406 MHz signal is activated, a 121.5 MHz signal is turned on.
The 121.5 MHz signal is used by SAR to home in on the beacon as they
approach it.
The 406 MHz signal is detected by multiple satellites and from that
information the location of the beacon can be calculated. This data alone
is sufficient for SAR to find persons or ships in distress in a reasonable
timeframe. However, as a further enhancement, some beacons have a
GPS engine onboard. This feature allows the beacon to acquire current
location coordinates from an internal GPS receiver or download
coordinates from an external GPS receiver. The coordinates are added
to the ID of the unit, which is transmitted with the 406 signal. This
enables the SAR authorities to locate the beacon to an accuracy of 110
yards (100 m).
