Inside GNSS Media & Research

MAY-JUN 2018

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34 Inside GNSS M A Y / J U N E 2 0 1 8 www.insidegnss.com Cospas-Sarsat specifications and per- formance standards, and of determining their position anywhere on the globe. The distress alert and location data is provided by Cospas-Sarsat Participants to the responsible SAR services. Cospas- Sarsat cooperates with the ICAO, the International Maritime Organization (IMO), the International Telecommu- nication Union and other international organizations to ensure the compatibil- ity of the Cospas-Sarsat distress alerting services with the needs, the standards and the applicable recommendations of the international community. It is today the most important worldwide rescue system, having been used from 1982 to December 2016 to provide assistance in rescuing at least 43,807 people in 12,664 events. From the beginning, Cospas-Sarsat has been integrated to aircraft safety and security systems with two types of beacons: ELT (Emergency Locator Transmitter), attached to the aircra and mandatory in most of them; and PLB (Personal Locator Beacons), attached to the pilot, widely spread in general aviation. Aviation domain today rep- resents 20% of the 2 million deployed beacons. In 2016, the Cospas-Sarsat system answered to 876 SAR events (177 distresses were related to the aviation domain); contributing to save 2,057 lives (355 lives involved in aeronautical SAR events). Thanks to the efficient com- munication link between the Cospas- Sarsat Mission Control Centre (MCCs), and the Rescue Coordination Centers (RCCs), the ground operational seg- ment of Cospas-Sarsat in general, and the aeronautical branch in particular, has reached the rank of the most per- forming SAR system as Cospas-Sarsat has been involved in half of the distress events managed by RCCs around the world. Over the last 34 years, with 30 oper- ational MCC deployed in 30 countries all around the world, and more than 100 RCC/SPOC, Cospas-Sarsat con- solidated its international SAR network and earned a rich experience in coordi- nation of information and rescue means in all the events it treated. Every year, new countries join the program and contribute to the Cospas-Sarsat ground segment. Today, t he Cospas-Sa rsat space segment is composed of five satellites in Low-Earth Orbit, eight satellites in Geostationary Orbit, and 37 satel- lites in Medium Earth Orbit, equipped with SAR payloads to receive and for- ward distress messages broadcasted by the Cospas-Sarsat SAR beacons. The Cospas-Sarsat system is free of charge for the user and entirely financed by the partners of the program. Figure 2 illustrates the nominal oper- ation chain of the Cospas-Sarsat system and the Return-Link use (violet arrows); the three space segments of Cospas-Sar- sat are represented: the Low Earth Orbit SAR (LEOSAR) space segment, the Medium Earth Orbit SAR (MEOSAR) space segment and the Geostationary orbit SAR (GEOSAR) space segment: 1. Distress beacons are activated by aircraft (ELT and ELT(DT)), ships (EPIRB: Emergency Position Indicat- ing Radio Beacon) or individual users (PLB: Personal Locator Beacon) 2. The SAR payloads aboard Cospas- Sarsat satellites (including Galileo satellites) relay the alert to LUT 3. The Local User Terminals (MEO- LU T, L E OLU T a nd GE OLU T ) detect, demodulate and localize the distress beacon signals 4. The LUT forwards the alert data (including the independent location computed by MEOLUT and LEO- LUT) to the appropriate MCC (i.e. the MC in charge of the area where the beacon is localized) 5. e Mission Control Centres (MCC) distributes alert data to Rescue Coor- dination Centres (RCC) 6. RCC organizes and coordinates SAR services and operations In addition, each Cospas-Sarsat beacon can be localized either thanks to the position encoded in the alert message transmitted or by the indepen- dent localization of the alert provided by the Cospas-Sarsat ground segment. is independent localization is based on the capacity to localize the beacon that transmitted the signal based on the reception characteristics of the signal by the Cospas-Sarsat ground segment. With the LEOSAR system, it relies on the Doppler effect but requires several bursts and is disturbed by the beacon motion, w it h t he MEOSAR system relying on the Frequency of Arrival and Time of Arrival of the signal and basi- cally consists in a triangulation just like what is done with GNSS. It eliminates the risks linked to GNSS, as the SAR operators dispose at any time of an esti- mation of the location of the beacon. b. ELT(DT) used in the MEOSAR system In parallel of the MEOSAR evolution, Cospas-Sarsat is also developing new standards of beacons: • ELT(DT) (Emergency Locator Trans- mitter for Distress Tracking) a spe- GRICAS FIGURE 2 The Cospas-Sarsat system (source: Cospas-Sarsat)

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