Anatomy Of A Rescue - ACR Electronics ResQLink PLB-400 Product User Manual

Y1-03-0343 Rev. A
How the Beacon Works
How your beacon summons 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 network 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 tens of thousands of lives, and
counting, since its inception.
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 forces via a Rescue
Coordination Centre (RCC). The distress
message contains the beacon UIN and on some models, the GPS location of the beacon.
Additional information about the beacon is accessed by SAR forces 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 forces 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 on board (all ACR PLB's currently manufactured include a GPS engine on board).
This feature allows the beacon to acquire current location coordinates from an internal GPS
receiver. The purpose of this feature is the send an even more precise location of the beacon to
the satellites (i.e., latitude and longitude data). This helps SAR to reach the location even
faster.
Company Confidential

Anatomy of a Rescue

Learn more about the Cospas-Sarsat
satellite system: www.cospas-sarsat.org
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