Satellite Detection - ACR Electronics ENGLISH Product Support Manual

1.3

SATELLITE DETECTION

1.3.1 The 406 PLB and GyPSI™ 406 PLB transmit an encoded phase modulated radio signal to the
satellite portion of the COSPAS-SARSAT System. The system was developed and implemented
by the COSPAS-SARSAT Partners (Russian Federation, Canada, France and the United States).
1.3.2 COSPAS-SARSAT is an international system that uses Russian Federation and United States low
altitude, near-polar orbiting satellites that assist in detecting and locating activated 406 MHz
Satellite beacons. The Russian Federation provides aboard COSMOS navigation spacecraft
COSPAS payloads that are inter-operable with the SARSAT System. In addition to weather and
environmental sensors, SARSAT payloads, provided by Canada and France, are carried aboard the
United States National Oceanic and Atmospheric Administration's (NOAA's) Advanced TIROS
environmental satellites.
1.3.3 COSPAS and SARSAT satellites receive distress signals from the 406 PLB and GyPSI™ 406
PLB transmitting on the frequency of 406.028 MHz. The COSPAS-SARSAT 406 MHz satellite
signal consists of a transmission of non-modulated carrier followed by a digital message format
that provides identification data. The 406 MHz system uses spacecraft-borne equipment to
measure and store the Doppler-shifted frequency data along with the satellite digital data message
including GPS data, and time of measurement. This information is transmitted in real time to an
earth station called the Local User Terminal (LUT), which may be within the view of the satellite,
as well as being stored for later transmission to other LUTs. In the real-time mode, the signal
detection is limited to a mutual satellite-LUT circular visibility area of about 2500 km radius that
moves with the satellite along its track. However, because of the stored-mode capability at 406
MHz, the need for this mutual PLB-satellite-LUT visibility is not essential, and the system is fully
functional in just the global mode.
1.3.4 The LUT processes the Doppler-shifted signal and determines the location of the PLB; then the
LUT relays the position of the distress signal to a Mission Control Center (MCC) where the
distress alert and GPS location information is immediately forwarded to an appropriate Rescue
Coordination Center (RCC). The RCC dispatches Search and Rescue (SAR) forces.
.
1.3.5 The COSPAS-SARSAT System includes 38 LEOSAR LUT Stations, 9 GEOSAR LUT stations
and 24 Mission Control Centers that provide real-time as well as global-mode coverage for the
northern hemisphere, while the southern hemisphere is presently served primarily by the global-
mode. Additional LUTs and MCCs are planned for installation in the near future both in the
northern and southern hemispheres.
The addition of the GEOSAR Satellite system greatly improves the reaction time for a SAR event.
This satellite system has no Doppler capabilities at 406 MHz but will relay the distress alert to any
of the LUT stations. When there is GPS data included in the distress message this will instantly
tell SAR authorities where you are located, hence by not having to await the transit of the next
LEOSAR satellite.
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Y1-03-0169 Rev. B