Abstract: A network has wireless access points, each configured for bi-directional communication, using a first radio protocol, with a communication device that has been associated with the access point by an association data exchange. Each access point is also configured to receive, at a first data rate using the first radio protocol, a multicast radio message and to forward the multicast message onto the network. A radio transmitter is configured to send data at a second data rate, using a second radio protocol different from the first radio protocol. A wireless communication unit transmits a multicast radio message at the first data rate using the first radio protocol. It also receives data from the radio transmitter at the second data rate using the second radio protocol and decodes the data.

Abstract: A network has wireless access points, each configured for bi-directional communication, using a first radio protocol, with a communication device that has been associated with the access point by an association data exchange. Each access point is also configured to receive, at a first data rate using the first radio protocol, a multicast radio message and to forward the multicast message onto the network. A radio transmitter is configured to send data at a second data rate, using a second radio protocol different from the first radio protocol. A wireless communication unit transmits a multicast radio message at the first data rate using the first radio protocol. It also receives data from the radio transmitter at the second data rate using the second radio protocol and decodes the data.

Abstract: A monitoring system is provided that includes a three dimensional position determination system for determining the three dimensional coordinates of one or more mobile units. The system includes at least one zone in which the system is arranged to raise an alarm when the rate of change of a vertical coordinate of a mobile unit is less than a predetermined value.

Abstract: A position determination system is provided comprising one or more fixed base units and one or more mobile units, wherein the system is arranged to determine the horizontal position of a mobile unit based on the proximity of said mobile unit to at least one base unit and wherein the system is arranged to determine the height of said mobile unit based on the air pressure sensed at the mobile unit and the air pressure sensed at one or more of the base units. The use of pressure sensors to determine height reduces the complexity of the infrastructure required for 3D positioning. The invention finds particular benefit in patient care and monitoring environments and in object tracking and inventory systems. The invention also extends to mobile units for use in the system, intelligent buildings fitted with the system and to methods of determining the position of mobile units.

Abstract: A network has wireless access points, each configured for bi-directional communication, using a first radio protocol, with a communication device that has been associated with the access point by an association data exchange. Each access point is also configured to receive, at a first data rate using the first radio protocol, a multicast radio message and to forward the multicast message onto the network. A radio transmitter is configured to send data at a second data rate, using a second radio protocol different from the first radio protocol. A wireless communication unit transmits a multicast radio message at the first data rate using the first radio protocol. It also receives data from the radio transmitter at the second data rate using the second radio protocol and decodes the data.

Abstract: Static transmitter stations are used to determine the position of a mobile receiver unit. Each transmitter station transmits an ultrasonic signal including a transmitter-specific phase-shifting signature. The receiver unit receives a signal and identifies a transmitter station by its signature. It uses the received signal and the identity of the source transmitter station to determine the position of the mobile receiver unit. The signature may include two patterns phase-shift-key (PSK)-encoded on respective carrier signals of the same frequency but different phase, with the patterns being offset from each other by a transmitter-specific offset. The signal from the transmitter station may also include a PSK-encoded message.

Abstract: The position of a mobile unit (12) within a detection zone is determined. An acoustic signal is emitted from the mobile unit and received along a first path (54). An echo of the signal is received after reflection from a surface (46) within said detection zone. The position of the mobile unit (12) within the detection zone is determined from the times of arrival of the signal and echo.

Abstract: An identification device includes an ultrasound transmitter unit and an outer housing which receives said transmitter unit, said outer housing including one or more apertures which are sealed by a membrane, said membrane being substantially transparent to ultrasound when compared to the rest of the housing.

Abstract: Static transmitter stations are used to determine the position of a mobile receiver unit. Each transmitter station transmits an ultrasonic signal including a transmitter-specific phase-shifting signature. The receiver unit receives a signal and identifies a transmitter station by its signature. It uses the received signal and the identity of the source transmitter station to determine the position of the mobile receiver unit. The signature may include two patterns phase-shift-key (PSK)-encoded on respective carrier signals of the same frequency but different phase, with the patterns being offset from each other by a transmitter-specific offset. The signal from the transmitter station may also include a PSK-encoded message.

Abstract: A transmitter device transmits an ultrasonic signal encoding a binary identifier. Each bit position in the identifier is associated with a pair of frequencies and with first and second time positions in the signal. The bit value determines which of the pair of frequencies is transmitted at the first time position, with the other being transmitted at the second time position. A receiver device receives the signal. Each bit position of the identifier is decoded based on the strength of the received signal at (a) the first frequency and first time position associated with the particular bit position, (b) the associated first frequency and second time position, (c) the associated second frequency and first time position, and (d) the associated second frequency and second time position. The decoded identifier is used to determine information relating to the position of a mobile one of the devices.

Abstract: An identification device comprising an ultrasound transmitter unit (16) and an outer housing (6) which receives said transmitter unit (16), said outer housing (6) comprising one or more apertures (32) which are sealed by a membrane, said membrane being substantially transparent to ultrasound when compared to the rest of the housing.

Abstract: A network has wireless access points, each configured for bi-directional communication, using a first radio protocol, with a communication device that has been associated with the access point by an association data exchange. Each access point is also configured to receive, at a first data rate using the first radio protocol, a multicast radio message and to forward the multicast message onto the network. A radio transmitter is configured to send data at a second data rate, using a second radio protocol different from the first radio protocol. A wireless communication unit transmits a multicast radio message at the first data rate using the first radio protocol. It also receives data from the radio transmitter at the second data rate using the second radio protocol and decodes the data.

Abstract: A method of receiving data coded on an ultrasonic signal comprising: detecting said ultrasonic signal using a microphone (4) having its greatest response below 20 kilohertz or a microphone (4) adapted for human speech reception; and decoding said signal to determine said data.

Abstract: Static transmitter stations are used to determine the position of a mobile receiver unit. Each transmitter station transmits an ultrasonic signal including a transmitter-specific phase-shifting signature. The receiver unit receives a signal and identifies a transmitter station by its signature. It uses the received signal and the identity of the source transmitter station to determine the position of the mobile receiver unit. The signature may include two patterns phase-shift-key (PSK)-encoded on respective carrier signals of the same frequency but different phase, with the patterns being offset from each other by a transmitter-specific offset. The signal from the transmitter station may also include a PSK-encoded message.

Abstract: A position determination system is provided comprising one or more fixed base units and one or more mobile units, wherein the system is arranged to determine the horizontal position of a mobile unit based on the proximity of said mobile unit to at least one base unit and wherein the system is arranged to determine the height of said mobile unit based on the air pressure sensed at the mobile unit and the air pressure sensed at one or more of the base units. The use of pressure sensors to determine height reduces the complexity of the infrastructure required for 3D positioning. The invention finds particular benefit in patient care and monitoring environments and in object tracking and inventory systems. The invention also extends to mobile units for use in the system, intelligent buildings fitted with the system and to methods of determining the position of mobile units.

Abstract: The position of a mobile unit (12) within a detection zone is determined. An acoustic signal is emitted from the mobile unit and received along a first path (54). An echo of the signal is received after reflection from a surface (46) within said detection zone. The position of the mobile unit (12) within the detection zone is determined from the times of arrival of the signal and echo.

Abstract: A method of receiving data coded on an ultrasonic signal comprising: detecting said ultrasonic signal using a microphone (4) having its greatest response below 20 kilohertz or a microphone (4) adapted for human speech reception; and decoding said signal to determine said data.

Abstract: An ultrasound position determination system includes a base unit and at least one mobile unit. Each of the mobile and base units are operable to transmit and receive ultrasonic signals. The mobile unit is adapted to transmit a predetermined signal in dependence upon the state of transmission of the base unit. The base unit is adapted to determine the time taken for the signal to pass from the mobile unit to the base unit and thereby calculate a distance between the mobile unit and the base unit.

Abstract: An identification device comprising an ultrasound transmitter unit (16) and an outer housing (6) which receives said transmitter unit (16), said outer housing (6) comprising one or more apertures (32) which are sealed by a membrane, said membrane being substantially transparent to ultrasound when compared to the rest of the housing.

Abstract: An ultrasound position determination system includes a base unit and at least one mobile unit. Each of the mobile and base units are operable to transmit and receive ultrasonic signals. The mobile unit is adapted to transmit a predetermined signal in dependence upon the state of transmission of the base unit. The base unit is adapted to determine the time taken for the signal to pass from the mobile unit to the base unit and thereby calculate a distance between the mobile unit and the base unit.