If spot is using GPS, wouldnt that be more accurate?
I am not an expert at all, but from the research I have been doing, this is my understanding.
SPOT receives a GPS signal from the GPS satellite network (typical GPS function). Then, when you want to transmit anything, emergency or non-emergeny, it uses the GlobalStar network.
PLB's use the Search and Rescue Satellite network (SARSAT - the 406 Mhz network), which is constantly monitored by NOAA and the Air Force. PLBs will use this system to triangulate your location (much like a GPS system would), then transmit your location through the SARSAT, along with your PLB's unique ID (which would be registered to you so they can identify you).
In addition, PLB's today usually include a GPS receiver too. If so, the GPS coordinates will be transmitted through the SARSAT system as well.
Further, the PLB's also have a low range homing device. This sends out a signal that can be directly monitored within a couple miles. This signal does not rely on satellites at all. This allows rescuers to home in on you once they get within a couple miles.
The differences I think worth considering are:
- My understanding is that GlobalStar doesn't have as much coverage as the SARSAT. If you need to transmit a distress signal on SPOT and you do not have GlobalStar coverage, you are SOL.
- PLB's interface directly with the established search and rescue network, continually monitored by government agencies. SPOT relies on privately owned infrastructure, and private services to relay your search and rescue information to the authorities.
-PLB's require no subscription. SPOT does, but I would image they would transmit a distress signal even if it came from a unit where the service has expired... not sure about that though.
-PLB's have a fixed service life of about 5-6 years. They use very strong batteries, and you cannot simply change the batteries. I do not know if SPOT has a fixed service life or not.
-For whatever it is worth, I have read many negative reviews of SPOT, specifically stating that messages were not getting transmitted in a timely manner. Not sure how much credence you put in internet reviews, but if there is an issue with signals getting through on a device like this, it concerns me.
-PLB's have redundancy. (Can use both SARSAT and GPS Network for location calculation, and by transmitting on both the satellite network, and having the short range beacon.)
-Cost. Over a 5-6 year service life, SPOT will cost much more then a $250 PLB.
-Features. While SPOT has many cool features, for me, the priority is search and rescue. Further, I believe some of the higher end PLB have many of the same tracking features SPOT has. Of course, the price will go up from $250, and I would guess would also require subscription fees.