Patent ID: 6298229
Filing Date: 2001-10-02
Classification: G01S,H04B

Abstract:
A GPS receiver for periodically determining a location and reporting the location even during intermittent shadowing, the GPS receiver comprising:a GPS circuit comprising:an antenna;a radio frequency (RF) and analog-to-digital (A/D) circuit connected to the antenna;a memory device connected to the RF and A/D circuit; anda correlator circuit connected to the memory;a controller connected to the GPS circuit for periodically instructing the GPS circuitry to power on, retrieve and process a first number of RF signals from a plurality of GPS satellites to obtain first GPS location data wherein each of the first number of RF signals is retrieved from a different one of the plurality of GPS satellites;a memory device connected to the controller for storing the first GPS location data; andan emergency signal generator connected to the controller and communicating an emergency signal to the controller, the controller commanding the GPS circuitry to power on in response to the emergency signal and a second number of RF signals is received from GPS satellites, each of the second number of RF signals is received from a different one of the plurality of GPS satellites,wherein if the second number of RF signals is equal to the first number of RF signals, the controller processes the second number of RF signals to obtain second GPS location data and provides the second GPS location data for transmittal to a central station, and wherein if the second number of RF signals is less than the first number of RF signals, the controller retrieves the first GPS location data from the memory device and provides the first GPS location data for transmittal to the central location.