So whats the difference from a SPOT. Both use the same navigation system for location right? I have a SPOT and I think it is less money. Is it less effective?
Separate systems, personally, I would consider the SPOTS and similar devices less effective for distress purposes for several reasons (which I list below), which include the distress function being a secondary feature for them.
Summary of the differences:
SPOT, DeLorma, etc are communications devices that work over commercial networks. How long it takes your message to get through depends on the amount of traffic on the network. I would assume that distress messages would be given priority, but you would have to check with the company, however, even if they are given priority, there are other issues.
First, the part of the RF spectrum that they operate in is licensed by the FCC for commercial use, so they are subject to power restrictions. Less power means you need a better shot at a satellite to enable the satellite to receive the signal and the signal is more affected by terrain and foliage.
Second, a distress signal is picked up by their satellite and routed to their network control center, which has to relay information to search and rescue personnel.
Third, these devices only have satellite communication capability, which means that if you can't find a satellite or get a reliable link to one, you don't have any communications.
Personal Locator Beacons (whatever brand) are specifically designed for relaying distress messages, so they operate in a different part of the RF spectrum under different rules and there is a system of satellites with a dedicated channel that only listens for these devices. This the same systems used for ships and aircraft.
PLBs have two (relative to SPOTs, etc) high power transmitters, one broadcasts on the satellite channel and the other broadcasts on a VHF radio that is used by general aviation. It's "only" 5 watts, but it's a lot more than the SPOTs and similar devices, so it is less affect by terrain, foliage etc, but they still require line of sight to a satellite or aircraft.
The satellite signal has your identification and position and broadcasts it to the satellites, which relay the signal directly to the Air Force Search and Rescue Coordination Center at Langley AFB, Virginia. The Rescue Coordination Center will verify whether or not it is a false alarm and can then directly task search and rescue units.
The VHF radio signal is broadcast on 121.5 MHz, which is the general aviation Guard frequency. Every airport and the vast majority of private and commercial aircraft monitor that frequency at all times. The signal has a very distinct tone that any aviator will recognize instantly as a distress call and they will report it.
That signal is also used by search and rescue teams to triangulate the position of the transmitter, I'm sure you've seen the shows where they track animals with the radio-location collars. SAR teams and aircraft use the exact same principle.
I know that ACR offers a package that requires a subscription where you can send "I'm okay" messages using the test function, but there are a limited number of times that you can do it before the software inhibits tests in order to ensure that the battery will operate for 24 hours if activated.
PLB also have a "recommended" battery replacement period of 5 years, the batteries may last longer, but life safety devices have a regular replacement interval in order to ensure that the battery will work correctly.
Finally, the PLBs do not require any type of external device to operate them (the SPOTS, etc, require a smartphone or computer to configure them, their distress function doesn't, but I don't know if that requires any prior configuration) and they don't require any subscription.
Obviously, I'm biased to the PLB. Messaging capability is nice, getting my butt of a mountain in an emergency is a necessity, so I want the device that is best suited for that function.
Hope that helps.
