In reply to MM0FMF:
If you are going North of Edinburgh I suggest you analyse the SPOT
coverage maps and latency to send carefully before punting.
+1 for this.
I’ve done a fair bit of research in this area (mostly driven around the legal adoption of COSPAS/SARSAT Personal Locator Beacons for use on land in the UK).
I’ve undertaken this research for two reasons, firstly it is something I am interested in and secondly because the use of these systems is increasing and some Mountain Rescue events have already been initiated through PLBs and SPOT trackers.
Firstly I’d agree that this sort of thing isn’t really relevant for SOTA spots.
If you are a solo walker and concerned about this type of thing you need to ask yourself a few questions before selecting a solution.
Do you want a proven (tens of thousands of successful activations), very reliable system for declaring an emergency anywhere on the surface of the globe? But you don’t want “I’m OK” or “I’m here, track me please!” capabilities. The solution for this is a COSPAS/SARSAT PLB, eg the McMurdo FastFind - other PLBs are available. This has been shown to work under trees and on one occasion when someone had fallen down a steep sided hole with a very limited sky view. Coverage for this is set to be further improved with further overlapping receiver satellites being launched from 2015. The 406MHz PLBs usually send precise GPS derived positions, but even if this fails they can be triangulated. The devices also emit a localiser tone on 121.1MHz which ground or air assets can use to close in on your location. You buy the device REGISTER IT WITH THE MCA (for the UK) and just remember to carry it with you. There are no ongoing rental or usage costs. Test it regularly (there is a test function) and replace the battery at the manufacturers recommended intervals, normally every five years or more. Any live use of one of these PLB type devices goes directly to the nearest government “Mission Control Centre”. UK registered devices go to the UKMCC which sits within the Air Rescue Coordination Center (ARCC) at RAF Kinloss. There have been a handful of invocations of PLBs on land in the UK. (this is what I carry)
Do you need this to work anywhere on the globe and you want “I’m OK” and/or “Track me” messaging? If so then you need a satellite return service that is global. The only truly global public satellite comms service is Iridium, which uses a constellation of 60+ satellites in interlocking orbits that mean that you should always be able to communicate with at least one satellite unless you are indoors or in a very steep sided valley or gorge. Units available from companies like DeLorme and YellowBox plus others. Most “plans” for this require payment of an annual “airtime” charge and a charge for messages sent. Emergency messages go to a US Company who will pass the messages onto government agencies, for examples the ARCC in the UK.
Do you only need this to work in defined areas and you want tracking and I’m OK type messages. For this you can look at SPOT messenger. It uses satellites in low latitude orbits for outbound communication, therefore you must be able to “see” the satellites above the horizon. Something that gets tricky at higher latitudes and also if you happen to be on the north side of a mountain (in the Northern Hemisphere). I’ve done some actual personal field testing with SPOT tracking and found it to be less than reliable under even light tree cover and in a steep sided valley. Testing was done in North Wales. Emergency messages go to a US Company who will pass the messages onto government agencies, for examples the ARCC in the UK. There have been a handful of emergency invocations with SPOT in the UK.
Personally, if I wanted tracking, I’d go for one of the Iridium based systems rather than SPOT. “You pay’s your money, you make’s your choice”
As I say, I don’t want tracking, so I just carry a COSPAS/SARSAT PLB.