EPIRB'S
Because the duty cycle of the transmitter is so short it will reduce the drain on the battery and the time between transmit cycles will allow other EPIRBs to transmit simultaneously while the satellite is passing overhead. The EPIRB identification is digitally encoded hexadecimal signal which provides the serial number of the EPIRB and this allows SAR to consult the database for the name of the vessel. And as previously mentioned the newer ones may have the position inserted in the message.
The EPIRB also contains a low power homing transmitter (25 milliwatt) that emits a continuous signal on 121.5 MHz. This allows the SAR units to "home" in on the beacon. Most of the EPIRBs also have a strobe light to proved on-scene units with a visuallD of the EPIRB. As mentioned the 121.5 MHz signal is also picked up by other satellites like the NOAA.
The Federal Communications Commission requires that each EPIRB be registered. This registration is done by the card enclosed when the EPIRB is purchased. There is no fee and the card is sent to NOAA directly. They in turn make the registration data base available to all SAR organizations world wide. There is a proof of registration label that is to be .attached to the EPIRB.
GMDSS REQUIREMENT, ships are required to meet certain ship radio equipment general requirements which:
a) Includes a Satellite EPIRB capable of transmitting a distress alert through the polar orbiting satellite service in the 406 MHZ band;
b)The EPIRB must be installed in an easily accessible position, ready to be manually released and capable of being carried by one person into a survival craft. It must also be capable of floating free if the ships sinks and automatically activated when afloat;
c)The EPIRB must be capable of manual activation and deactivation;
Shipboard personnel preparing to abandon ship should retrieve the 406 MHZ EPIRB from the bracket and take to the survival craft for manual activation.
The EPIRB must be capable of automatically activating after floating free from the mounting bracket. It must able to float free from the sinking ship at a depth not to exceed 4 meters (at a list of up to 45 degrees) these float free operations are done by a hydrostatic Automatic Release Mechanism (ARM) on the EPIRB mounting bracket.
There is a replacement date label is affixed to the ARM and the ARM must be replaced by this date .
Watertight Integrity, EPIRBs are required to be watertight to a depth of 10 meters for a period of at least a 5 minutes. They must be capable of being dropped into the water from a height of 20 meters without damage and of floating upright in calm water.
Some of the newer models will activate when detected in water, salt or fresh, and automatically activate the beacon regardless of the switch position. All EPIRBs have a buoyant lanyard used as a tether to secure the beacon to a survival craft or to yourself if need be.
There are severe penalties in store for the vessel who activate either by inadvertently or on purpose (hoax or gross negligence) and the 100ierai Communications Commission will take action.
The EPIRBs should be tested and examined as part of the pre departure checks on every vessel. Check for expiration dates on both the ARM and EPIRB, and to see if the proof of registration is affixed. You can check for signal by using the small FM radio tuned to 100 MHz while the EPIRB is in the test mode. This will assure that the 121.5 MHz signal is working and we can assume that the 406 MHz transmitter is working also. Most EPIRBs are equipped with a test switch. The US Coast Guard requires a monthly test (and must be done on the first FIVE minutes of the hour). The test switch places the EPIRB into a non radiating position and signal is kept to a minimum.
The batteries in the EPIRB are to have sufficient capacity to operate the EPIRB for a minimum of 48 hours. And in all cases of survival equipment there is a month and year of replacement marked on the battery. The unit cannot be used beyond this date. The battery must be replaced at this time as there is no grace period permitted.
