Hi all,

Just got a pair of GT-31s from and I'm setting them up. I've followed Tom Chalko's setup for GT-31s. However, I seem to remember reading somewhere, probably on Tom Chalko’s Site, that you can set the timing (may have been GT-11s) so there was a 0.25 second or 0.5 second lag when reading. The idea being that combining this with a reading without the lag give increased accuracy.  I can’t seem to find the setting, can’t remember what it was called, does anybody know?

Is there anything else I must do in the set-up for the Dual GT-31?


Hi Neil.
The GT-11 has the facility to synchronise or offset the time of the data points. The GT-31 come with every unit synchronised to the same whole second and that can't be changed in the menu.

The only other thing about setting up dual GPS in a helmet is to try to put them so they are sideways to the direction of travel so that slight turning movement of your head does not accelerate one more than the other. In an Aquapac, put them head to head.
I've now own 2 GT-31's and want to know when you download the tracks do you combine the two files? or evaluate them seperately.