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S&R

Search And Rescue (S&R)

The Search and Rescue Satellite Programme collects accurate and timely distress alert data and location information and distributes this to search and rescue authorities. The programme coordinates with national and international organisations on frequency management, satellite, emergency beacon and search and rescue issues, and maintains a national register for 406 MHz emergency beacons.

The S&R package fitted to Metop consists of two systems, SARR and SARP.

The Search And Rescue Repeater (SARR) performs the traditional function of a relay station forwarding the distress calls to the mission control centres. The Search And Rescue Processor (SARP-3) provides the added ability to receive and process distress messages from 406 MHz beacons and relay them to the authorities via the SARR pallet.

SARR consists of a receiver assembly and a transmitter assembly. The receiver assembly receives the Emergency Locator Transmitters on 121.5, 243.0 and 406.05 MHz. It down converts its received energy to selected intermediate frequency bands. These bands are then summed with 2.4 kbps data from the SARP-3 unit and the resulting signal phase-modulates the 1544.5 MHz down-link carrier frequency via the L-band down-link.

The SARP-3 instrument is composed of one Receiving and Processing Unit (RPU), which has cold redundancy. It is used to receive messages from numerous 406 MHz distress beacons (400 bps), of which there are two kinds: existing beacons (STD), and new generation beacons (NG). The parameters contained in the received messages (long or short format) allow the RPU to determine the name, frequency, time and location of the beacon. The instrument extracts the binary content of each 24-bit word message and determines the message priority and its Doppler frequency. Once re-formatted, the memory content (up to 2048 messages) is transmitted (playback transmission) via the 2.4 kbps input port of the Canadian SARR transmitter, when there are no real-time messages to transmit.

The SARR receives and down-links emergency signals from aircraft and ships in distress. In addition, it provides a down-link for data received by the SARP-3. The SARR receives distress beacon signals on three separate frequencies, translates them to L-band and retransmits them to Local User Terminals (LUTs) on the ground. These terminals process the signals, determine location of the beacons, and forward this information to a rescue Mission Control Centre (MCC).

SARP-3 receives and processes emergency signals from the 406 MHz beacons of aircraft and ships in distress. It determines the name, frequency and time of the signal. These pre-processed data are then fed in real time to the SARR instrument for immediate transmission to SARSAT (Search And Rescue Satellite) distress terminals on the ground. This means that with a 406 MHz beacon, a distress message can be sent to the appropriate authorities from anywhere on Earth 24 hours a day, 365 days a year.

At the end of 2004, the worldwide population was estimated at 375,000 for the 406.05 MHz frequency beacon. In addition, there are 600,000 beacons utilising the 121.5 MHz frequency. Satellite processing of distress signals from 121.5 MHz is due to terminate on 1 February 2009 however, due to the higher reliability of the 406.05 MHz frequency.

Since its inception in 1982 the Cospas-Sarsat System has provided distress alert information which has assisted in the rescue of over 20,531 persons in 5,752 distress situations. In 2005 the System provided information which was used to rescue 1,666 persons in 435 distress situations.

SARR is provided by the National Oceanic and Atmospheric Administration (NOAA) and the Department of Defence Canada and developed by EMS Montreal, Canada. SARP-3 is provided by Centre National d'Études Spatiales (CNES) Toulouse, France and developed by Thales Elancourt, France, and Alcatel Alenia Space Toulouse, France.

For more information, see and , as well as ESA's and pages.

S&R Summary Budgets


	Power budget		SARP: 22 W, SARR: 47 W

	TX frequency		SARR 1544.5 MHz (± 400 kHz)

	RX frequencies		SARR: 121.5 (± 20 kHz), 243 (± 30 kHz), 406 MHz (± 80 kHz), SARP: 406 MHz

	Data rate		2.4 kbps biphase signal to the SARR Pallet

	Processing		SARP - three messages received/processed in parallel

	Memory capacity		SARP - 2048 messages (extended to 2560 by command)

	Dimensions		SARR RPU: 365mm x 280mm x 194 mm, SARR RX: 458mm x 458mm x 166 mm, SARR TX: 350mm x 369mm x 122mm

	Mass		SARP RPU: 15kg, SARR RX: 15.2 kg, SARR TX: 5.2kg

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