Appeal No. 2002-2169 Page 2
Application No. 09/163,286
have telescopes for sighting angles to targets. Such electro-optical hybrids are called
"total stations." (Id. at 2.)
An EDM equipment meter derives its accuracy from an internal frequency source
such as a crystal oscillator. The frequency of the oscillator, however, can drift over time
and with age. Exposure to extreme environments can also upset delicate calibrations
of the frequency source. (Id. at 3.)
Accordingly, the invention aims to calibrate a total station automatically and
precisely. The total station includes a global positioning system ("GPS") receiver, an
oscillator, and an EDM meter. When the receiver is locked onto and tracking GPS
satellites, cesium-rubidium clocks in the satellites are used to calibrate the oscillator,
which drives the meter. The appellants assert that baseline measurements made by
the meter are "not subject to mis-calibrations and drift as long as the satellite navigation
receiver is locked onto and tracking the orbiting navigation satellites." (Id. at 5.)
A further understanding of the invention can be achieved by reading the following
claim.
1. A surveying instrument, comprising:
a satellite navigation receiver with a pulse-per-second output
derived from an atomic time standard used in a related orbiting navigation
satellite;
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