ACR Electronics 2774 Informações Técnicas descarregar pdf (Página 16)

Y1-03-0148-2 Rev. H

6.3 Shore Based Maintenance (SBM) for SOLAS Vessels, IMO MSC/Circ. 1039

The Maritime Safety Committee approved guidelines for shore-based maintenance of satellite beacons, for the

purpose of establishing standardized procedures and minimum levels of service for the testing and

maintenance of satellite beacons. First Shore Based Maintenance on all ACR EPIRBs is due at the date of the

first battery replacement.

6.4 Annual Testing for SOLAS Vessels, IMO MSC/Circ. 1040

SOLAS regulation IV/15.9 dictates annual testing of 406 MHz satellite EPIRBs. Testing should be carried out

using suitable test equipment capable of performing the relevant measurements. All checks of electrical

parameters should be performed in the self-test mode, if possible.

SECTION 7 – THE SEARCH AND RESCUE SYSTEM

7.1 General Overview

Beacons provide distress alerts via radio transmission on 406 MHz to the LEOSAR satellites of the COSPAS-

SARSAT network. The RapidFix™ can also transmit a distress alert (acquired by the internal or external GPS)

to the GEOSAR network that includes GPS latitude and longitude coordinates.

The message transmitted is unique for each beacon, which provides identification of the transmitter through

computer access of registration files maintained by the National Oceanic and Atmospheric Administration or

other national authority*. Remember, SAR forces will know who you are, what type of vessel you have, your

homeport, and who to contact that might know of your current situation ONLY if your beacon has been properly

registered. This will help expedite the launch of a rescue operation. 406 MHz beacons are required to have

their registration updated every two years.

*The national authority is the governmental body responsible for EPIRB registration database administration

for the country for which the EPIRB is programmed.

Once the 406 MHz signal is relayed through the LEOSAR and/or GEOSAR network, SAR forces determine

who is closest, and then proceed to the beacon using the 121.5 MHz homing frequency.

7.2 Satellite Detection

EPIRBs transmit to the satellite portion of the COSPAS-SARSAT system. COSPAS-S

ARSAT is an

international system that utilizes Russian Feder

ation and United States’ low altitude, near-polar orbiting

satellites (LEOSAR). These satellites assist in detecting and locating activated 406 MHz satellite beacons.

COSPAS and SARSAT satellites receive distress signals from EPIRBs transmitting on the frequency of 406

MHz. The COSPAS-SARSAT 406 MHz beacon signal consists of a transmission of non-modulated carriers

followed by a digital message format that provides identification data. The 406 MHz system uses Satellite-

borne equipment to measure and store the Doppler-shifted frequency along with the beacon’s digital data

message 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.

The LUT processes the Doppler-shifted signal from the LEOSAR and determines the location of the beacon,

then the LUT relays the position of the distress to a Mission Control Center (MCC) where the distress alert and

location information is immediately forwarded to an appropriate Rescue Coordination Center (RCC). The RCC

dispatches Search and Rescue (SAR) forces.

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, SAR authorities instantly know your location to

within 110 yards (100 m). This speeds up the reaction time by not having to wait for one of the LEOSAR

satellite to pass overhead. Because most of the search and rescue forces presently are not equipped to home

in on the 406 MHz Satellite beacons signal, homing must be accomplished at 121.5 MHz.

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