Interesting test today. About 145 mi, 5 hour, 15 minute ride in NE Alabama/NW Georgia (Lookout Mt. and environs) with SPOT strapped to pillion (photo). This was the best place I could think of that would give it a decent view of the sky without being shielded by my body in a tank bag -- save sticking it on top of my helmet. It sees more of the sky there than it does on the dashboard of the car where I've been having better than 90% success with messages in tracking mode.
Results were a little disappointing. Of approximately 30 10-minute intervals in tracking mode, 16 messages made it through. I was riding secondary and tertiary paved and dirt roads (no single or dual track trails) so there was little overhanging vegetation, not that there are any leaves on the trees now anyway. Most of the points agreed with the Garmin GPS track except for two: one was about a mile off and the second was about 10 miles off. On the way back home it missed 4 consecutive messages while riding on top of the mountain. The spurious locations are more troubling.
I can't come up with a good explanation for the difference in performance between the cage and bike. Yes, the antennas were pointing up and the batteries have maybe 300 messages on them (the 30% capacity alarm signal was not going off). Temps were in the 50s, clear sky, no wind, barometric pressure 30.05 inches, etc. etc. Great biking weather.
Suggestions anyone? Next I'll test OK message throughput.
Question: if you're moving when you hit the OK button does it send the same location three times over 20 minutes, or is the location updated each time it sends? I suspect it's the former, right?