Appeal No. 1999-0172
Application 08/334,733
means for intermittently communicating global positioning
data between said remote receiver transmitters and said base
station;
reference receiver means positioned at a known position
for receiving signals from the global positioning satellite
system to determine a reference apparent position and for
calculating an error correction based on the difference
between the known position and the apparent position;
the base station including means for receiving global
positioning data of a remote receiver from said communicating
means, means for receiving said error correction from said
reference receiver means, means for deriving a corrected
location of said remote receiver using said error correction
and said global positioning data, and means for displaying the
location of said remote receiver in said freight yard.
10. A method for determining locations of freight
containers in a freight yard comprising:
attaching a number of GPS receivers to a number of
freight containers in said freight yard;
operating each receiver to receive GPS signals indicative
of receiver position;
intermittently operating each receiver to transmit data
indicative of receiver identification and receiver position,
including the substep of determining time and initiating said
intermittent transmission based on said time;
receiving said receiver identification and receiver
position at a base station;
correction said receiver positions at the base station to
determine corrected positions of said receivers; and
displaying the identification and corrected position of
said receivers in said freight yard.
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