Abstract: A pulse shaping apparatus for shaping an input optical pulse into an output optical pulse having substantially constant optical power, includes a modulator that acts upon the input optical pulse in response to a control signal. A sampling unit samples a portion of the input or output pulse and generates a sample signal that corresponds to the optical power of the input or output optical pulse. In a preferred embodiment, the sampling unit includes a power splitter that splits off sample portion of the input or output pulse, and directs the sample portion to the photodetector which generates the sample signal. Processing of the sample signal may be performed in either an analog or digital form.

Abstract: In the field of Acousto-Optic processors, it is desirable to sample and multiplex a large quantity of time varying data generated by a photodiode array. However, current multiplexers cannot sample at a high enough rate in order to process all of the data generated in real time, resulting in a reduced sampling bandwidth and therefore a loss of information. A data filtering apparatus and method of filtering a plurality of data signals overcomes this problem by providing a channel selection logic unit which instructs a multiplexer to only sample data generated which is above a predetermined threshold value, thereby omitting to sample data which is of little information value.

Abstract: A mobile phone antenna comprising a belt which is adapted to be worn by a user and which comprises an antenna arrangement which in use is coupled to the mobile phone transceiver.

Abstract: The present invention provides an antenna assembly (10) comprising a plurality of planar tiles (20). Each of the tiles carries a planar array of sets (22) of antenna elements (47-50) arranged to be operated as a phased array antenna. The tiles are arranged in an orientation which is conformal to a contour of an underlying structure. In use, only those tiles which are capable of communication in the steered direction are enabled, while those which are not capable of communicating in the steered direction are not used.

Abstract: A dual polarised antenna 1 has two types of antenna elements combined. Each type of antenna element is formed on a planar substrate. The substrates are furnished with inter-engaging slots to enable assembly of the elements. Signal feeds are connected to the active parts of the elements by means of connection points furnished at off axis positions. The off-axis positions for connection enable an arrangement in which the locus of the effective phase centres of the antenna element scan be co-located yielding a convenient arrangement with good performance.

Abstract: The invention provides a positional system intended to supplement positional information derived by means of a Global Positioning System (GPS), so as to provide positional data coverage in situations where the GPS data may be unreliable, for example due to local attenuation of satellite signals, in order to permit members of a group traversing difficult terrain to retain reasonably accurate information as to the whereabouts of the other group members should the GPS system fail. The positional system of the invention provides each group member with a readily transportable and relatively inexpensive inertial navigation system to generate approximate positional data and utilises radio location techniques to improve the accuracy of the approximate positional data.

Abstract: An arrangement for multi-standard duplex filtering for mobile terminals in a telecommunications system. The arrangement includes a substrate on which a first array of filter elements and a second array of filter elements are formed. The filter elements have different frequency bands in accordance with mobile telecommunications standards. The first array filters an incoming signal received from an antenna and provides an output at port in accordance with a matched frequency band of one of the standards. The second array filters a signal to be applied to port in accordance with a matched frequency band of one of the standards prior to transmission through antenna. The filter elements may comprise surface acoustic wave devices formed on a single substrate.

Abstract: A broadband telecommunications switch (1), for switching packets of data received on a plurality of input ports (5) to plurality of bandwidth limited output ports (10), comprising for each input port (5) a control processor (22) which operates to send request data for each of a plurality of switching periods to each output port (10), which request data is representative of a requirement for communications bandwidth from said output ports (10) sufficient to accommodate packets of data received at said input ports (5) for switching to said output ports (10) for the switching period. Each of said bandwidth allocators (24) responds to said request data by generating bandwidth allocation data appertaining to an allocation of a share of the bandwidth of the output port (10) to the input port (5), which share of bandwidth said input port (5) uses to switch data from said input ports to said output ports during said switching period.

Abstract: A method is presented for operating a phased array antenna comprising a number of sub-arrays. The method comprises the steps of introducing phase offsets into signals received from/transmitted to each element in the antenna, to provide directional transmit or receive sensitivity in a first direction; summing signals received from each element in each sub-array to provide respective sub-array signals; introducing respective phase offsets into the respective sub-array signals to adjust the direction of maximum sensitivity within a sensitivity envelope defined by the phase offsets applied to each element of the antenna as a whole.

Abstract: A direct conversion receiver which compensates for interfering signals introduced during processing. Direct conversion is achieved using direct detection techniques which introduce interfering signals which become inseparable from the wanted signal. A pilot signal (202) is added to an input RF signal (200) prior to passing the summed signal (206) to four separate paths (210, 212, 214, 216). Signal (206) is modulated so that the phase is different in each path using local oscillator signals and switches (230, 232, 234, 236), and then digitised by ADCs (260, 262, 264, 266). Correction is introduced into respective paths (210, 214) by cancellation loops (310, 314) to compensate for unwanted signals prior to the paths being grouped so that the pairs of digitised signals (272, 300; 276; 304) which are 180° out of phase with one another are subtracted to provide output inphase and quadrature signals (220, 224).

Abstract: A time interval measurement system for the timing between events occurring at two spaced apart locations comprising at each location a dual frequency Global Positioning System (GPS) receiver having operatively associated with it a GPS antenna, wherein both the GPS receiver and the antenna are dual frequency (L1, L2) and the former is capable of both Coarse Acquisition (C/A) Code and carrier phase measurements, an accurate frequency reference source giving local time, a data-logger for logging the GPS data, a Time Interval Counter (TIC) means is used to measure the time of a local event relative to the local time and further comprising a central processor system (CPS) and a communication system via which the logged GPS data and time interval data are received at the CPS from each location, the CPS being arranged to derive a time-offset figure, in accordance with a predetermined algorithm which is indicative of the difference between times as measured in dependence upon the frequency reference sources at the tw

Abstract: A system for locating an object that produces identifying signals comprises a plurality of receiver sites arranged in an array for receiving signals from the object and for receiving a common time reference in the form signals received from a global navigation system. The array comprises a reference receiver site and three auxiliary receiver sites that are connected to the reference site by data links. Each receiver site receives signals from the object and timing control signals from a global navigation system. Each site determines a time difference between the receipt of the object signals and the timing signals, the auxiliary sites providing data signals on data links to the reference site where the location of the object is determined.

Abstract: There is provided an autonomous off-board defensive aids system (100) for use with a host craft (102), for example, with combat aircraft or submarines. More particularly, the host craft (102) deploys a plurality of controllable off-board units (104, 106) to counter an offensive threat or to engage in autonomous offensive actions. The controllable off-board units (104, 106) implement active stealth facilities: each off-board unit (104, 106) having a receiver unit for detecting impinging detection pulses, for example radar or sonar pulses, and a transmitter unit for generating an artificial detection pulse profile, for example “spoofing” or masking the presence of the host craft. The controllable off-board units are of two types: tethered (104) and free moving (106). The off-board units (104, 106) can have conventional propulsion apparatus, for instance, propellers, rockets or jets. Off-board units (104, 106) each have control apparatus which allows the off-board units (104, 106) to co-operate.

Abstract: A method of deriving a route through a network comprises analysing constraints imposed by a stream of data to be routed through the network; calculating a best path through the network between a first node (A) and a second node (G); and setting up, between the first and second nodes, a bearer trail which satisfies the constraints. The method further comprises analysing the chosen route using a state machine to ensure compliance before defining the bearer trail.

Abstract: In a method and apparatus for reducing the bit rate of transmitted signals in a telecommunications system, a speech recognition device is operated in parallel with a speech coding device in a transmitter terminal. An analog input signal from a microphone is digitized in an analog-to-digital converter to provide a digital signal which is applied to both the speech coding device and the speech recognition device. An output signal for transmission via an antenna is formed by combining output signals from the speech coding device and the speech recognition device via a switch, recognized speech being converted to codewords which replace packets or sequences of packets of the coded signal corresponding thereto. In a receiver terminal, an antenna receives the transmitted signal and passes it to both a speech coding device and a speech generator prior to being converted to an analog signal for a speaker.

Abstract: A time offset measurement system for the timing of events at spaced apart locations comprising at each location, a dual frequency Global Positioning System (GPS) receiver having operatively associated with it a GPS antenna, wherein both the GPS receiver and the antenna are dual frequency (L1, L2), and the former is capable of both Coarse Acquisition (C/A) Code and carrier phase measurements, a frequency reference source giving local time, a data-logger for logging GPS data, a Time Interval Counter (TIC) used to measure the time of a local event as defined by the frequency reference source relative to time as determined based on on GPS data and further comprising a central processor system (CPS), and a communication system via which the logged GPS data and time interval data, are received at the CPS from each location, the CPS being arranged to derive in accordance with a predetermined algorithm, for each pair of sites a primary time-offset figure based on a direct signal path between the sites, and a secondar

Abstract: The method of operating an uplink of a CDMA mobile telecommunications system provides optimization of power control accuracy, or rate change responsiveness for at least one communications a channel. Rate information is provided which indicates (a) the rate of the current frame, or (b) which indicates the power of a subsequent frame. Selection between (a) and (b) is possible by transmitting global information to all terminals in a cell, or by instructing individual terminals by use of a bit within the rate information bits carried within each slot of a control channel.

Abstract: An access authentication system is provided for authenticating access for visitors to a wireless local area network (W-LAN), the operator of which administers a visitor authentication, authorisation and accounting (VAAA) server. A user requesting visiting access to the W-LAN, is required to have a valid cellular mobile account, a portable computing device with a browser and a valid W-LAN card from another operator that administers a home authentication, authorisation and accounting (HAAA) server. The user, on requesting visiting access to the W-LAN, inputs, via the VAAA server, identity information that enables the HAAA to issue a personal identification number (PIN) which is encoded and forwarded, preferably by way of a short message service (SMS), to the user's mobile telephone.

Abstract: The invention provides an operating protocol for Local Area Network (LAN) systems capable of coping with the problems of user-mobility between LANs. Such mobility is afforded particularly by wireless LAN (WLAN) systems, whereby a user subscribing to a LAN operated by a so-called Home Operator connects, as a “visitor”, to one or more other LAN sites; basing such connection, for charging and other operational purposes, on that user's subscription with its Home Operator. The inventive protocol links a user's identity with the address of the Home Operator, and stores this information at the visited LAN site, thereby permitting a visiting user, once authenticated by user-interaction, as a visitor with regard to a particular LAN, to revisit that LAN for as long as its authentication with the Home Operator remains sound, without the need for further user intervention.

Abstract: Described herein is a method for making bandwidth allocation for data to be sent from a plurality of ingress forwarders or LICs (310, 312, 314, 316) to a plurality of egress forwarders or LICs (320, 322, 324, 326) across a routing device (330). The data may be unicast and/or multicast. The bandwidth allocation is calculated in accordance with ingress forwarder multicast queue occupancy for each ingress forwarder (312, 314, 316), the number of multicast cells received by egress forwarders (322, 324, 326) from the ingress forwarders in the last bandwidth allocation period, and the bandwidth allocated to non-real time multicast flows from ingress forwarders (310, 312, 314, 316) to egress forwarders (320, 322, 324,326).