Location and tracking system

A mobile radio-frequency communication system, comprising:

• a network of at least two base stations arranged to transmit the same signals to at least one mobile radio-frequency transceiver, and receive signals form the one or more mobile radio-frequency transceivers;
• a reference receiver located at a fixed location a known distance from each of the base stations and including measuring means to measure the times of arrival of signals transmitted from the base stations;
• determination means to use the known distances and measured times to determine the relative time offsets of transmissions from each base station;
• and
• location means to use the determined relative time offsets to calculate the position of a mobile transceiver in the network area using techniques involving comparison of the times of arrival of signals from the base stations at the mobile transceiver;
• wherein the mobile transceiver synthesizes a wide aperture while it is moving to provide additional information for position calculation.

A mobile radio-frequency communication system, comprising:

• a network of at least two base stations arranged to transmit the same signals to at least one mobile radio-frequency transceiver, and receive signals from the one or more mobile radio-frequency transceivers;
• a reference receiver located at a fixed location a known distance from each of the base stations and including measuring means to measure the times of arrival of signals transmitted from the base stations;
• determination means to use the known distances and measured times to determine the relative time offsets of transmissions from each base station;
• and
• location means to use the determined relative time offsets to calculate the position of a mobile transceiver in the network area using techniques involving comparison of the times of arrival of signals from the base stations at the mobile transceiver;
• wherein the mobile transceiver synthesizes a wide aperture while it is moving to provide additional information to reduce multi-path effects.

A method of finding the position of a mobile radio-frequency transceiver in a communication system comprising a network of at least two base stations arranged to transmit the same signals, comprising the steps of:

• locating a reference receiver at known distances from the base stations;
• measuring the times of arrival at the reference receiver of signals transmitted from the base stations;
• determining the relative time offsets of transmissions from each base station, using the known distances and measured times;
• and
• calculating the position of a mobile transceiver in the network area using the determined relative time offsets;
• said method comprising the additional step of calculating the impulse response of the channel between a base station and a mobile transceiver and using this information in the mobile transceiver to reduce multi-path effects.

A method of finding the position of a mobile radio-frequency transceiver in a communication system comprising a network of at least two base stations arranged to transmit the same signals, comprising the steps of:

• locating a reference receiver at known distances from the base stations;
• measuring the times of arrival at the reference receiver of signals transmitted from the base stations;
• determining the relative time offsets of transmissions from each base station, using the known distances and measured times;
• and
• calculating the position of a mobile transceiver in the network area using the determined relative time offsets;
• said method comprising the additional step of synthesizing a wide aperture while the mobile transceiver is moving to provide additional information for position calculation.

A method of finding the position of a mobile radio-frequency transceiver in a communication system comprising a network of at least two base stations arranged to transmit the same signals, comprising the steps of:

• locating a reference receiver at known distances from the base stations;
• measuring the times of arrival at the reference receiver of signals transmitted from the base stations;
• determining the relative time offsets of transmissions from each base station, using the known distances and measured times;
• and
• calculating the position of a mobile transceiver in the network area using the determined relative time offsets;
• said method comprising the additional step of synthesizing a wide aperture while the mobile transceiver is moving to provide additional information to reduce multi-path effects.