GPS receiver for emergency location reporting during intermittent shadowing

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;
• and
• a 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 four RF signals from a plurality of GPS satellites to obtain first GPS location data wherein each of the four 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;
• and
• a mobile phone connected to the controller and communicating an emergency signal to the controller upon dialing a predetermined number, 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 four RF signals, the controller processes the second number of RF signals to obtain second GPS location data, provides the second GPS location data for transmittal to a central station and stores the second GPS location data in the memory device, and wherein if the second number of RF signals is less than four 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.

A method for periodically determining a location and reporting the location even during intermittent shadowing of a GPS receiver, the method comprising the steps of:

• powering on the GPS receiver at a first time;
• receiving a first number of RF signals using the GPS receiver during the first time wherein each of the first number of RF signals is received from a different one of a plurality of GPS satellites;
• processing the first number of RF signals received during the first time to obtain first GPS location data used to determine the location;
• storing the first GPS location determined from the first number of RF signals received during the first time;
• powering down the GPS receiver after receiving the first number of RF signals during the first time;
• responding to an emergency signal by powering on the GPS receiver at a second time;
• receiving a second number of RF signals from GPS satellites during the second time wherein each of the second number of RF signals is received from a different one of the plurality of GPS satellites;
• processing the second number of RF signals received during the second time to obtain second GPS location data and transmitting the second GPS location data to a central station wherein the second number of RF signals is processed and the second GPS location data is transmitted only when the second number is equal to the first number of RF signals;
• and
• retrieving the first GPS location data and transmitting the first GPS location data to the central station to obtain the location wherein the first GPS location data is retrieved and the first GPS location data is transmitted only when the second number is less than the first number of RF signals.

A method for periodically determining a location and reporting the location even during intermittent shadowing of a GPS receiver, the method comprising the steps of:

• powering on the GPS receiver at a first time;
• receiving four RF signals using the GPS receiver during the first time wherein each of the four RF signals is received from a different one of a plurality of GPS satellites;
• processing the four RF signals received during the first time to obtain first GPS location data used to determine the location;
• storing the first GPS location determined from the first number of RF signals received during the first time;
• powering down the GPS receiver after receiving the first number of RF signals during the first time;
• responding to an emergency signal by powering on the GPS receiver at a second time;
• receiving a number of RF signals from GPS satellites during the second time wherein each of the number of RF signals is received from a different one of the plurality of GPS satellites;
• processing the number of RF signals received during the second time to obtain second GPS location data, transmitting the second GPS location data to a central station and storing the second GPS location data wherein the second number of RF signals is processed, transmitted and stored only when the second number of RF signals is equal to four RF signals;
• and
• retrieving the first GPS location data and transmitting the first GPS location data to the central station to obtain the location wherein the first GPS location data is retrieved and the first GPS location data is transmitted only when the second number of RF signals is less than four RF signals.