A PLB as the only link between you
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Two different satellite systems to capture the signal from Personal Locator Beacons
GEO satellites continually view large areas of the Earth from approximately 70 degrees North to 70 degrees South latitudes and can provide immediate alerting and identification of a 406 MHz beacon. They cannot determine the location of a PLB using Doppler processing, because they are "stationary".
The signals received by LEO satellites are relayed to a network of LUTs (Local User Terminals) that locate the PLB by measuring the Doppler shift caused by the motion of the satellite with respect to the beacon. This process can locate a 406 MHz beacon within an accuracy of approximately 3 miles (5 km).
Not good enough
It can take up to 90 minutes for a LEO satellite to come overhead and to get a position of a PLB that sends a distress signal. In some cases this could be too long to save someone.
A GPS receiver incorporated in a PLB
This gives a huge amelioration for two reasons:
- The location accuracy is much better than the accuracy obtained by the Doppler shift measurements of the LEO satellites.
- The PLB sends its GPS coordinates with the distress signal, so no need to wait for the LEO satellites anymore.
Two requirements added to Personal Locator Beacon standards
The U.S. added two notable requirements to the international Personal Locator Beacon standards. They must include a 25 milliwatt 121.5 MHz analog homing signal. Inserted into the homing signal at the insistence of the FAA is a Morse code P to distinguish a PLB from an ELT (Emergency Locator Transmitters), as used in aviation.
PLB registration
Your PLB must be registered in your country of residence. Each Personal Locator Beacon is equipped with a UIN (Unique Identifying Number) This number is a 15 digit alpha-numeric code. This code is what is transmitted in the electronic burst to the satellites. The UIN is linked to a computer database. The electronic burst provides Search and Rescue with your location, while the UIN links to the database and provides your name, address, phone number and any pertinent information such as medical problems, of which Search and Rescue should be aware. When you buy a Personal Locator Beacon, it is imperative that you register it. In doing so, they will tie all your personal information into the 15 digit UIN. That way, when your beacon is activated any where on the Planet, Search and Rescue will know, who you are, where you are and how to handle any pre-existing medical problems when they reach you.
When to use your Personal Locator Beacon
Your Personal Locator Beacon must only be activated in a distress situation and only in remote areas where conventional communication facilities are not available. A distress situation involves an incident concerning grave danger to the safety of human life.
What happens when you activate your registered PLB?
By the time the signal is picked up and transferred to the Mission Control Center, rescue authorities already know your name and have a digital profile direct from your PLB registration form. Armed with your personal stats, they can take a number of initial steps to determine the nature of the emergency. First, they will try to contact you to make sure that the PLB was not erroneously switched on. Next, they will move on to an emergency contact, usually a friend or family member who may know your general whereabouts-and should have a copy of your float plan or itinerary. Now that they know exactly what they are looking for they will be able to determine the best way to make contact and give you assistance.
Some modern PLBs with incorporated GPS receiver
Before buying a Personal Locator Beacon you should check if it is approved in your country of residence. Otherwise you will be unable to register your purchase with the competent Authorities.
ACR is the manufacturer with more PLBs on the market than any competition. Above is their TerraFix 406 GPS. Approved by the FCC for sale in the US. Size in inches 1.74 x 5.71 x 3.03 (4.4 x 14.5 x 7.7 cm) and a weight of 12.11 ounces (343 gr) w/o holster; 13.3 oz (378 gr) with holster.
And this is ACR's newest MicroFix 406 MHz PLB. Also approved for sale in the US. Size in inches 1.4 x 5.85 x 2.21 (3.55 x 14.9 x 5.6 cm) and a weight of 10 oz (283.5 gr).
The Fastfind Plus GPS of McMurdo is approved for sale in the US. Dimensions in inches 6 x 3 x 2.1 (15.2 x 7.6 x 5.3 cm) and a weight of 11.4 oz (323 gr).
Microwave Monolithics' MicroPLB comes in two versions Type GX will operate for 48 hours at -20 degrees Celsius and type GP will operate 24 hours at -20 degrees Celsius. Dimensions in inches for both types (?) 1.1 x 2.35 x 5.95 (2.8 x 6.0 x 15.1 cm) with a weight of 9.5 oz (269 gr).
The Kannad 406 XS-2 from Martec has the following dimensions in inches 6.06 x 2.75 x 1.34 (15.4 x 7 x 3.4 cm) at a weight of 13.4 oz (380 gr).
The new MT410G from Australian GME has the following dimensions in inches 5.3 x 2.8 x 1.5 (13.5 x 7.1 x 3.8 cm) and a weight of 8.8 oz (250 gr).
For the many remote areas of the world
If you plan to travel to areas where cell phone coverage is non-existent or not very reliable, a Personal Locator Beacon could make the difference between being found or not in case of an emergency.
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