Locating system and method using a mobile communications network

A locating system using a mobile communications network and a positioning system, comprising:

• a reference positioning receiver located at a first transmitter site of the mobile communications network, the reference positioning receiver having known position coordinates and operable to receive first position signals from the positioning system, the reference positioning receiver further operable to generate correction data in response to the first position signals and the known position coordinates;
• the first transmitter site of the mobile communications network coupled to the reference positioning receiver and operable to receive correction data generated by the reference positioning receiver;
• a second transmitter site of the mobile communications network coupled to the first transmitter site, the second transmitter site operable to transmit in a control channel correction data received from the first transmitter site;
• and
• a mobile unit in communication with the second transmitter site and the positioning system, the mobile unit operable to receive correction data transmitted by the second transmitter site, the mobile unit further operable to receive second position signals from the positioning system and to determine the location of the mobile unit in response to the second position signals and the correction data.

An apparatus for locating a vehicle within the service area of a cellular telephone network and a positioning system, comprising:

• a positioning receiver on the vehicle and operable to receive first position signals from the positioning system;
• a mobile communications device on the vehicle and coupled to a transmitter site of the cellular telephone network, the mobile communications device operable to receive in a control channel from the transmitter site correction data generated at the transmitter site;
• and
• a processor on the vehicle and coupled to the positioning receiver and the mobile communications device, the processor operable to determine the location of the vehicle in response to the first position signals and the correction data.

A method for locating a mobile unit within the service area of a cellular telephone network and a positioning system, comprising:

• receiving first position signals from the positioning system at a reference positioning receiver having known position coordinates, the reference positioning receiver located at a transmitter site of a cellular telephone network;
• generating, at the transmitter site, correction data in response to the first position signals and the known position coordinates;
• receiving in a control channel, from the transmitter site, correction data at a cellular transceiver in the mobile unit;
• receiving second position signals from the positioning system at a mobile positioning receiver in the mobile unit;
• and
• determining the location of the mobile unit in response to the second position signals and the correction data.