Originally posted by maggot:
A GPS receiver calculates its position by measuring the distance
between itself and three or more GPS satellites. Measuring the time
delay between [b]transmission and reception of each
GPS microwave signal gives the distance to each satellite, since
the signal travels at a known speed. The signals also carry
information about the satellites' location. By determining the
position of, and distance to, at least three satellites, the
receiver can compute its position using trilateration.[3] Receivers
typically do not have perfectly accurate clocks and therefore track
one or more additional satellites to correct the receiver's clock
error.
http://en.wikipedia.org/wiki/GPS
Now you know why the battery drain is so fast 
[/b]
The transmission you highlighted refers to the signal
transmitted by the satellites, not the GPS receiver.
This signal transmitted from the satellite contains a timecode.
When the GPS receiver receives this signal, it is timecoded too.
The time delay is then calculated by your GPS.
