Location system combining ranging measurements from GPS and cellular networks

A method comprising

• receiving a plurality of first type signals from a plurality of satellites using a mobile terminal;
• transmitting at least one second type of signal to a plurality of base stations using the mobile terminal;
• measuring a time of flight for each of the first type of signals received at the mobile terminal;
• measuring a time of flight for each of the second type of signals received at the plurality of base stations;
• converting each of a resulting time of flight measurements associated with each of the first type of signals to a corresponding first type of range value;
• converting each of a resulting time of flight measurements associated with each of the second type of signals to a corresponding second type of range value;
• and
• determining an approximate position of the mobile terminal using the first type of range values and the second type of range values.

An arrangement for use with a mobile telecommunications system in locating a mobile terminal, the arrangement comprising

• a satellite location system having a plurality satellites for outputting a plurality of first type signals;
• a plurality of base stations within the mobile telecommunications system;
• a location determining node within the mobile telecommunications system;
• and
• a mobile station in radio communication with at least one of the plurality of base stations for transmitting at least one second type of signal to the plurality of base stations, and further for receiving the plurality of first type signals from the plurality of satellites, measuring a time of flight for each of the first type of signals, and providing a range value for each of the first type of signals received to the location determining node;
• wherein the plurality of the base stations further receive the second type of signal from the mobile terminal, measure a time of flight for each of the second type of signals, and communicate a range value for each of the second type of signals received to the location determining node which is configured to determine an approximate position of the mobile terminal using the first type of range values and the second type of range values.

A shared clock arrangement comprising:

• a first clock outputting a first clock signal;
• a second clock outputting a second clock signal;
• a correlator that is connected to the first clock and the second clock
• for correlating the first clock signal with the second clock signal and output a correlated clock signal;
• a frame generator connected to the first clock and for receiving the first clock signal and outputting a corresponding generated frame signal;
• and
• a comparator connected to the correlator and the frame generator and for measuring the algebraic sum of the correlated clock signal and the generated frame signal and outputting a corresponding summed output clock signal.