Location device and system using UWB and non-UWB signals
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 location system and a portable location device, the portable location device comprising:
a first transmitter arranged to transmit ultra-wideband signals to the location system;
a receiver for receiving the non-ultra-wideband control signals from the location system; and
a control unit coupled to the receiver and arranged to control the transmission by the first transmitter of ultra-wideband signals in dependence on the non-ultra-wideband control signals received at the portable location device; and
the location system comprising:
a plurality of receivers for receiving the ultra-wideband signals from the portable device;
a second transmitter arranged to transmit the non-ultra-wideband control signals to the portable device; and
a location unit configured to determine the location of the portable location device by controlling the second transmitter to transmit the non-ultra-wideband control signals to the portable device and by using information derived from the ultra-wideband signals received from the first transmitter of the portable location device at more than one of the receivers of the location system.
2. A location system and a portable location device as claimed in claim 1 , wherein the second transmitter of the location system is arranged to periodically transmit non-ultra-wideband signals for reception at the receiver of the portable location device.
3. A location system and a portable location device as claimed in claim 1 , wherein the location system comprises a plurality of base stations each comprising one of the plurality of receivers and a handover unit, the handover unit being arranged to determine when handover of the portable location device from one of the base stations to another base station is to be performed and the system is arranged so that when such a determination is made the second transmitter of the location system transmits a non-ultra-wideband handover signal to the portable location device, and the control unit of the portable location device is arranged to change the channel on which it transmits ultra-wideband signals in response to reception of the handover signal by the receiver of the device.
4. A location system and a portable location device as claimed in claim 1 , wherein the second transmitter is arranged to broadcast or multicast the non-ultra-wideband signals to a plurality of portable devices.
5. A location system and a portable location device as claimed in claim 1 , wherein the first transmitter is operable to transmit non-ultra-wideband signals.
6. A location system and a portable location device as claimed in claim 5 , wherein the first transmitter is operable to transmit non-ultra-wideband signals containing an identifier that identifies the portable location device.
7. A location system and a portable location device as claimed in claim 6 , wherein the location device is arranged to transmit a non-ultra-wideband signal containing the identifier within a predetermined time of transmitting an ultra-wideband signal.
8. A location system and a portable location device as claimed in claim 7 , wherein one or more receivers of the location system are capable of receiving non-ultra-wideband signals and the location unit is arranged to attribute an ultra-wideband signal received at a receiver of the location system as being from a specific portable device in response to receiving a non-ultra-wideband signal identifying that device within a predetermined time of receiving the ultra-wideband signal.
9. A location system and a portable location device as claimed in claim 1 , wherein the location system comprises a plurality of location reference devices each including a handover unit operable to determine when handover of a portable location device from a first location reference device to a second location reference device is required.
10. A location system and a portable location device as claimed in claim 9 , wherein the second transmitter is arranged to transmit a non-ultra-wideband signal to the portable location device indicating that handover to the second location reference device is required if the handover unit of the first location reference device determines that such handover is required.
11. A location system and 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 in dependence on the received non-ultra-wideband signals.
12. A location system and 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 in dependence on the received non-ultra-wideband signals.
13. A location system and a portable location device as claimed in claim 1 , wherein the control unit is arranged to stop the first transmitter from transmitting ultra-wideband signals until a non-ultra-wideband signal of a predetermined type is received at the receiver of the portable location device.
14. A location system and a portable location device as claimed in claim 13 , wherein the first transmitter is arranged to transmit periodic ultra-wideband signals.
15. A location system and a portable location device as claimed in claim 1 , wherein the control unit is arranged to start the first transmitter transmitting ultra-wideband signals when the receiver of the portable location device receives a non-ultra-wideband signal of a predetermined type.
16. A location system and 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.
17. A location system and a portable location device as claimed in claim 1 , wherein the ultra-wideband signals are radio signals.
18. A location system and a portable location device as claimed in claim 1 , wherein the non-ultra-wideband signals are radio signals.
19. A location system and a portable device as claimed in claim 7 , wherein the control unit of the location device is arranged to control operation of the first transmitter in dependence on the received non-ultra-wideband control signals to transmit a non-ultra-wideband signal containing the identifier within a predetermined time of transmitting an ultra-wideband signal.
20. A location system and a portable location device as claimed in claim 19 , wherein the first transmitter is arranged to periodically transmit ultra-wideband signals to the location system.