Location system
A portable location device for use in a location system, the device comprising a transmitter for transmitting ultra-wideband signals, a receiver for receiving non-ultra-wideband signals and a control unit coupled to the receiver for controlling the operation of the device in dependence on the received non-ultra-wideband signals.
1. A portable location device comprising:
a transmitter arranged to periodically transmit ultra-wideband signals to a location system, the transmitter further arranged to transmit non-ultra-wideband signals;
a receiver for receiving non-ultra-wideband signals from a location system; and
a control unit coupled to the receiver, the control unit arranged to control the operation of the device in dependence on the received non-ultra-wideband signals;
wherein the location device is arranged to transmit a non-ultra-wideband signal containing an identifier that identifies the portable location device within a predetermined time of the transmission of one of the ultra-wideband signals.
2. A portable location device as claimed in claim 1 , wherein the receiver is arranged to receive non-ultra-wideband control signals from the location system, and the control unit is arranged to control the transmitter in dependence on the received non-ultra-wideband control signals to transmit the non-ultra-wideband signal containing the identifier.
3. A portable location device as claimed in claim 1 , wherein the control unit is arranged to control the rate at which the ultra-wideband signals are transmitted to the location system in dependence on the received non-ultra-wideband signals.
4. A portable location device as claimed in claim 1 , wherein the control unit is arranged to control the channel over which the ultra-wideband signals are transmitted to the location system in dependence on the received non-ultra-wideband signals.
5. A portable location device as claimed in claim 1 , wherein the control unit is arranged to control the channel over which the non-ultra-wideband signals are transmitted in dependence on the received non-ultra-wideband signals.
6. A portable location device as claimed in claim 1 , wherein the control unit is arranged to stop the transmitter from transmitting ultra-wideband signals until a non-ultra-wideband signal of a predetermined type is received by the receiver.
7. A portable location device as claimed in claim 1 , wherein the control unit is arranged to start the transmitter transmitting the ultra-wideband signals when the receiver receives a non-ultra-wideband signal of a predetermined type.
8. A portable location device as claimed in claim 1 , wherein the ultra-wideband signals are suitable for allowing the location of the portable location device to be calculated.
9. A portable location device as claimed in claim 1 , wherein the ultra-wideband signals are radio signals.
10. A portable location device as claimed in claim 1 , wherein the non-ultra-wideband signals are radio signals.