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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
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).
Y1-03-0233 Rev. D
www.cospas-sarsat.org.
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