Abstract: A master-slave distributed communications network includes a master node, a plurality of slave nodes. Each slave node is configured to store an address of the next node for a message to be routed on an uplink to the master node, and when sending a data packet to the master node it appends the pre-stored address and forwards the data packet to the next node thus lengthening the data packet, as the data packet is progressed from the slave nodes to the master node. For a downlink message, the master node using a pre-stored routing table includes in the data packet the addresses of all the slave nodes on the selected route. As the data packet is progressed from slave node to slave node, the address of each slave node which has forwarded the data packet is deleted thus shortening the overall length of the data packet.

Abstract: A master-slave distributed communications network comprises a master node (10), a plurality of slave nodes (12 to 22), and links (VL) operatively interconnecting the slave nodes and the master node in accordance with a routing plan. Each slave node has means for storing an address of the next node in the routing plan for a message to be routed on an uplink to the master node and when sending a data packet to the master node it appends the prestored address and forwards the data packet to the next node. If the next node is not the master node, it, in turn, adds the prestored address of the next following slave node to the data packet thus lengthening the data packet and re-transmits it, and so on until the data packet reaches the master node. For a downlink message, the master node (10) using a prestored routing table includes in the data packet the addresses of all the slave nodes on the selected route.

Abstract: A method for routing messages having a routing indicator across linked master/slave configured piconets. At each master node, a routing table is stored and at each hop a receiving master node performs a reception algorithm on the routing indicator, the result enabling the receiving node to identify a target node and whether that node is local to the receiving piconet or a node accessible through a piconet with which the receiving piconet is linked. In the latter instance, the receiving node performs a transmission rule on the result to generate a new routing indicator replacing the routing indicator, which is then transmitted with the message to the identified piconet.

Abstract: A method of transferring data signals between a primary station (10) and secondary stations (SL1 to SL5) of a master/slave radio network, comprises the primary station assigning the secondary stations to a plurality of categories (Z1, Z2). The primary station transmits beacon signals containing indications of those categories of the plurality for which it has data to be transferred. A secondary station operating in accordance with a wakeup sequence receives the beacon signals and determines if there is an indication of its category in a received beacon signal. If so, it transmits a request including an indication of its identity. The primary station checks to see if it has a data packet for the identified secondary station and, if it has, it transmits the data packet and, if not, it transmits a negative acknowledgement. Those secondary stations not participating in the exchange of messages can revert to a sleep mode thereby saving power.

Abstract: A signalling system includes a plurality of active transponders (10), an interrogation station (12) and a source (14) of switching signals. Each of the transponders has a microcontroller (20), a radio transceiver (34) for responding to radio interrogation signals from the interrogation station, the radio transceiver being coupled to the controller by way of switching means (36) which switches the transceiver on or off whilst leaving the microcontroller active, and a passive receiver (38) for receiving switching signals from the source of switching signals which signals are used by the microcontroller for switching-on or -off the transceiver. Transducers (26, 28, 30) may be coupled to the microcontroller for monitoring environmental features, such as ambient temperature and humidity, and data relating to the features is stored in a RAM (32) in readiness to be relayed to storage means (56) in the interrogation station (12) as and when required.

Abstract: A method of code phase correlation and apparatus (10 to 15) implementing the same is disclosed, the method comprising the steps of (a) receiving a subject signal comprising a target pseudorandom noise code; (b) generating early and late replica code signals corresponding to the target code; (c) correlating the subject signal with the early and late replica code signals and returning respective early and late correlation values; and (d) calculating a code phase discriminator for determining whether the target code has been acquired as a function of the sum of the early and late correlation values.

Abstract: A low power radio network comprises a master radio device (10) having a routing table (20), and a plurality of slave devices (SL1 to SL6), at least one of the slave devices has an inputting device (38, 40) and other of the slave devices (SL1 to SL4) being associated with end user devices (LUM1 to LUM4) compatible with the inputting device. In order to create a functional link between at least a predetermined end user device and the inputting device, the radio network is placed in a pairing mode in which the master device (10) activates the end user devices sequentially and at the activation of the predetermined end user device, the inputting device is activated which causes the routing table to create a pairing link.

Abstract: A master-slave distributed communications network comprises a master node (10), a plurality of slave nodes (12 to 22), and links (VL) operatively interconnecting the slave nodes and the master node in accordance with a routing plan. Each slave node has means for storing an address of the next node in the routing plan for a message to be routed on an uplink to the master node and when sending a data packet to the master node it appends the prestored address and forwards the data packet to the next node. If the next node is not the master node, it, in turn, adds the prestored address of the next following slave node to the data packet thus lengthening the data packet and re-transmits it, and so on until the data packet reaches the master node.

Abstract: A signalling system includes a plurality of active transponders (10), an interrogation station (12) and a source (14) of switching signals. Each of the transponders has a microcontroller (20), a radio transceiver (34) for responding to radio interrogation signals from the interrogation station, the radio transceiver being coupled to the controller by way of switching means (36) which switches the transceiver on or off whilst leaving the microcontroller active, and a passive receiver (38) for receiving switching signals from the source of switching signals which signals are used by the microcontroller for switching-on or -off the transceiver. Transducers (26, 28, 30) may be coupled to the microcontroller for monitoring environmental features, such as ambient temperature and humidity, and data relating to the features is stored in a RAM (32) in readiness to be relayed to storage means (56) in the interrogation station (12) as and when required.

Abstract: A method of transferring data signals between a primary station (10) and secondary stations (SL1 to SL5) of a master/slave radio network, comprises the primary station assigning the secondary stations to a plurality of categories (Z1, Z2). The primary station transmits beacon signals containing indications of those categories of the plurality for which it has data to be transferred. A secondary station operating in accordance with a wakeup sequence receives the beacon signals and determines if there is an indication of its category in a received beacon signal. If so, it transmits a request including an indication of its identity. The primary station checks to see if it has a data packet for the identified secondary station and, if it has, it transmits the data packet and, if not, it transmits a negative acknowledgement. Those secondary stations not participating in the exchange of messages can revert to a sleep mode thereby saving power.