Appeal 2007-0277
Application 10/270,236
ratio associated with a GPS satellite signal received by the marker, a power
associated with a GPS satellite signal received by the marker, and an in-band
power density of a signal received from a GPS satellite by the marker.
The invention is directed to a method of detecting errors in GPS accuracy.
The method involves the use of three pieces of information:
• GPS-related data;
• a derived GPS parameter; and
• an expected GPS parameter. GPS-related data is received at a marker and,
based on that data, a derived GPS parameter is calculated. The derived GPS
parameter is then compared with a corresponding expected GPS parameter and a
warning is issued if the comparison indicates an irregularity between the derived
GPS parameter and the corresponding expected GPS parameter.4
In accordance with the method set forth in claim 13, the derived GPS
parameter and the expected GPS parameter comprise at least one of the following:
• a quantity of GPS satellites received by the marker,
• a set of specific satellites received by the marker,
• a signal-to-noise ratio associated with a GPS satellite signal received by the
marker,
• a carrier-to-noise ratio associated with a GPS satellite signal received by the
marker,
4 The Specification (p. 2, ll. 15-20) describes the method in more simple terms:
According to an embodiment of the invention, there is provided a method for
detecting errors in GPS accuracy. The method includes determining an
initial GPS position of a marker, receiving GPS signals at the marker,
calculating, from the GPS signals, a GPS coordinate position of the marker,
comparing the GPS coordinate position and the initial GPS position, and
issuing a warning if the GPS coordinate position differs from the initial GPS
position by more than a predetermined amount.
3
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