EPIRB BATTERIES

[hellosailor]

"The manufacturers aren't keen to tell you if they have taken a shortcut "
What, even in Oz? (G)

I know that certain big-name electronics makers have actually employed what they sometimes call forensic engineers, who will literally take a newly designed circuit board and literally comb over it saying "We don't need that part" in order to make it cheaper to produce--and often, inferior to what was designed and actually certified for the market. Those unpopulated items on the circuit board usually were their victims.

The idea of letting the GPS module sleep every so often doesn't seem really crazy to me though. For someone in the water or about to be, perhaps moving at 2-6 knots? Even if that is a 30-minute sleep and the position is then 3 miles off, that still should be enough to get rescue assets launched, and well within the homing range of the 121.5 signal. Given how quickly a gen-3 GPS chip can wake from sleep and reacquire position, having them sleep for 5 or 10 minutes should really be a trivial matter. From the designers' perspective...games like that would allow for smaller batteries and smaller units, and that's got to be a competitive pursuit.

[Wotname]

Originally Posted by hellosailor

.........
The idea of letting the GPS module sleep every so often doesn't seem really crazy to me though. For someone in the water or about to be, perhaps moving at 2-6 knots? Even if that is a 30-minute sleep and the position is then 3 miles off, that still should be enough to get rescue assets launched, and well within the homing range of the 121.5 signal. Given how quickly a gen-3 GPS chip can wake from sleep and reacquire position, having them sleep for 5 or 10 minutes should really be a trivial matter. From the designers' perspective...games like that would allow for smaller batteries and smaller units, and that's got to be a competitive pursuit.

My bad, I didn't explain the issue very well in my previous post. You are correct, having the GPS asleep for 5 or 10 minutes is not a problem and the better beacons do it this way. IMO, 30 minute sleeps are getting borderline.

The real problem is when the GPS engine is only used once and the coordinates are transmitted only once or just gets repeated over and over again (i.e. not updated). The next worse is when the GPS is only active for say a couple of times in the first hour or two and then is turned off completely. As far as certification goes, such units can be described and sold as GPS embedded EPIRBs.

I think these dodgy techniques are not as prevalent in newly designed beacons as they once were.

[hellosailor]

Dodgy would be a way more polite term than I'd use for that!

Thanks for the info.