Abstract: 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.

Abstract: 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.

Abstract: A location system comprising a plurality of base units for enabling the locating of a device by means of one or more location signals communicated between the device and the base units and signal processing equipment for: i. determining the location of the device in dependence on the manner in which the location signal(s) is/are received and ii. deriving calibration data for calibrating the system in dependence on the manner in which the location signal(s) is/are received.

Abstract: A system for monitoring the presence of persons within a zone, the system comprising: one or more remotely detectable markers, each capable of being carried by a person; a first sensor arrangement capable of identifying the presence of the body of at least one person within the zone; a second sensor arrangement capable of identifying the presence of at least one marker within the zone; and a processing arrangement responsive to the first sensor arrangement and the second sensor arrangement to generate an alarm signal if the first sensor arrangement identifies the presence of a body without the second sensor arrangement identifying a marker corresponding in a first predetermined manner to that body.

Abstract: A location system comprises a plurality of transponders whose locations are detectable by a base system. The base system interrogates (51-55) the transponders one at a time in accordance with a schedule of consecutive time slots. In response to a priority request received (53) from one of the transponders, the base system interrupts the schedule and interrogates substantially immediately (56, 57, 55) the signaling transponder so as to determine its location with minimal latency.

Abstract: A location system comprises a plurality of transponders whose locations are detectable by a base system. The base system interrogates (51-55) the transponders one at a time in accordance with a schedule of consecutive time slots. In response to a priority request received (53) from one of the transponders, the base system interrupts the schedule and interrogates substantially immediately (56,57,55) the signalling transponder so as to determine its location with minimal latency.

Abstract: A user interface system for allowing users to initiate events comprises: a plurality of markers each having a marker identity; a plurality of portable readers each having a reader identity and arranged to read said marker identities from adjacent markers, and at least one base station arranged to communicate with said readers in a wireless manner, wherein at least one reader is provided with actuation means which when actuated by a user causes the reader identity of the reader and the marker identity of an adjacent marker to be transmitted by the reader to said base station, so as to cause, for at least one of said markers, said base station to initiate, directly or indirectly, an action which is at least partly determined by the reader identity of said reader.

Abstract: A system which enables the orientation of a device in a specified environment to be determined in relation to a plurality of sensing receivers positioned at known points in or around the specified environment. A directional transmission from a directional transmitter which forms part of a known face of the device is initiated by a trigger signal from a timing transmitter located so as to cause transmitted bursts of energy to enter the environment. Associated with the directional transmitter having is a timing receiver adapted to respond to any such trigger signals, to thereby initiate the directional transmission. At the beginning of a timeslot, the sensing receivers are reset, and the trigger signal is transmitted, to render the receivers ready to receive the directional transmission.

Abstract: A system which enables the position of each plurality of mobile labelled objects in a specified environment to be determined from the transit times to fixed receivers of ultrasound energy transmitted by object mounted transponders which are triggered by radio energy, wherein the specified environment is divided into cells each have a radio transmitter transmitting the radio triggered signals, these radio transmissions being multiplexed in accordance with identifying characteristics of the respective cells, no two cells with the same identifying characteristics overlapping one another.

Abstract: A system for determining the position of each of a plurality of objects in a specified environment by determining the transit times of slowly propagating measurement energy transmitted from a measurement energy transmitter on each object to a plurality of fixed measurement energy receivers in the specified environment, the transmission of the measurement energy being triggered by a burst of high speed propagating trigger energy into the specified environment from a trigger energy transmitter, the measurement energy transmitter on each object being triggered by an object-mounted trigger energy receiver, each burst of trigger energy being encoded so as to trigger one only of the measurement energy transmitters, wherein a coordinating control system determines the order in which the measurement energy transmitters are triggered, in response to updatable information relating to service demands of the trigger energy transmitter and/or objects.

Abstract: A system which enables the position of each of a plurality of movable labelled objects to be determined in an environment having two or more isolated zones, wherein the objects carry transponders which, in response to encoded radio signals, transmit ultrasonic signals of which the transit times to a plurality of fixed receivers are determined, the transponders in the different zones being triggered in a common timeslot but in staggered relationship for one zone as compared to another, and an algorithm is applied to verify the consistency of the transit times having regard to the possible movements of objects from one zone to another.

Abstract: A system for determining the position of a labelled object within an environment containing a plurality of detectors sensitive to energy of a first type and located at known positions therearound, wherein the object has a transmitter for transmitting energy of the first type, and each object is labelled by means of a receiver forming part of a communication link with a remote controlling transmitter for triggering the object-mounted transmitter. The transit time between the transmitter and each detector is used to determine the straight line distances between the object and the receivers, to enable the position of the object relative to the receivers to be determined. The arrival and departure of an object into and from the environment is determined by a second communication link from a second transmitter on each object, to a remote receiver. The two communication links may be combined in a bi-directional radio communication system.

Abstract: An ultrasonic location system for indoor environments, enabling the determination with high accuracy of the positions and orientations of objects to be tracked, wherein transmitting units (20, 22, 24) on the objects to be tracked transmit encoded ultrasonic pulses which are detected by receiver units (12 to 18) located by known positions around a room, and the receiver units are adapted to detect times-of-flight of the ultrasonic pulses in conjunction with decoding of the pulses to identify which time-of-flight applies to each transmitting unit.