Originally Posted by
gauvins
You are right. But the odds of a message not being transmitted are very small (roughly one over 10 000). My personal experience is that unsent messages are rare and easily detected at the source (no clear sky, etc. and you get blinking red lights) so you know that something is wrong. I don't recall reading any account referring to a unit apparently working yet messages not being received.
I don't know whether a duplex network is more likely to process your inbound message. I've used sat phones in the past (in the context of an ocean passage) and would not consider these devices on a bike expedition unless one has very extreme plans and wants to broadcast his/her adventure).
Ok, but I feel like you're trying to dismiss something as a non-issue, when it really is an issue. It's a simple fact that you don't know if your message has been received by the satellite or not. And I have definitely read quite a few reviews (I even quoted one earlier) that talked about times when they went on some trip only to discover when they got home that their updates had not gotten through. The simple fact is, you don't know. With a bidirectional system like the DeLorme, it might have times when it's having issues getting through, but at least you will know, because there is an ack as part of that process. If you don't get the ack, it probably didn't go through, but at least you know that.
Perhaps the Globalstar network of satellites has gotten better over the years, and if so then that's obviously a good thing for everybody. But it still doesn't get around what is a design issue with the system: You never know for sure if your update went through or not. And, despite the rose tinted spectacles, sometimes it doesn't.