GPS receiver for emergency location reporting during intermittent shadowing

US6298229A · kind A · utility

Assignee

• General Electric Company · US

Inventors

• Harold Woodruff Tomlinson, Jr. · Liverpool, US
• Daniel David Harrison · Delanson, US

Key dates

• Filing date: Dec 4, 1998
• Grant date: Oct 2, 2001
• Expiry date: Dec 4, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B1/3805
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A controller in a mobile telephone periodically commands GPS circuitry in the mobile telephone to power-on, capture and process GPS satellite signals. The signals are processed to obtain pseudo-range or time-difference data for at least one GPS satellite. After the signals are processed, the pseudo-range or time-difference data, GPS time, and satellite numbers are stored in non-volatile random access memory (RAM) and the GPS circuitry is powered off. When an emergency signal is present, the controller first commands the GPS circuitry to power-on, capture and process signals from four GPS satellites. If signals from at least four satellites are not present, the information stored in non-volatile RAM is read out. The processed data (if available), or else the data read out of the non-volatile RAM, are reported to a central location through the mobile telephone transmitter. The central location can then use the data to compute the present or last valid GPS location of the GPS receiver. The periodic sampling of the GPS signal minimizes power consumption and obtains a valid GPS location before shadowing occurs.