Originally posted by Gimbal I would guess that in order to save battery it doesn't acquire GPS positioning every second but only every minute, or third or what ever you choose.
It updates every Second - what that does is configure for how long its updating 'for'. You'll note that it speaks of overriding the Light Meter settings and extending them automatically based on the chosen setting..
So it would seem that the unit 'wakes up' based on the meter (i.e, half shutter if camera asleep or been idle) and then will continue to plot its position @ 1Hz (based on details on next page of specifications stating 1second update rate) for the duration specified.
This makes sense so that A: it doesn't constantly drain like you suggest, and B: is able to geo-tag any picture once awake without having to wait 2-3 seconds for a 3D lock again... as the light meter also triggers automatically when the camera is first turned on..
This means you can switch on, compose for a bit, then 'snap', and still have it tagged to the 10m RMS the unit supplies...
I'm almost convinced now that it uses the pTTL feedback packets maybe to pull the NMEA data (same ones that will light the flash symbol on ok exposure) - stamping the GPS lat-lon that the O-GPS1 transmits based on the normal flash trigger linked to the shutter.. and it'll work up to 1/4000 etc because it'll also fake out that it does HSS etc..
This is no doubt why Pentax state you cannot use dongles etc to use other pTTL flashes when using the O-GPS1...