Abstract: A method of compressing a character by determining an overall code specific to the character comprising the steps of: a) grouping the characters in terms of a common behaviour pattern; b) where the number of characters within that group is odd, creating a two new groups of character, one new group containing just one character and the other new group containing the remaining characters; c) for each new group from of step b) said groups from step a) which have an even number of characters, assigning a group specific code d) where there is more than one character in the group referred to in step c) assigning a character identifier code to identify an individual character within the group, e) the overall character code comprising of the cocatenated group specific and identifier codes.

Abstract: The Video Motion Anomaly Detector addresses the problem of automatically detecting events of interest to operators of CCTV systems used in security, transport and other applications, processing CCTV images. The detector may be used in a number of ways, for example to raise an alarm, summoning a human operator to view video data, or to trigger selective recording of video data or to insert an index mark in recordings of video data.

Abstract: In a method for improving signal extraction in a code division multiple access (CDMA) telecommunications system, a first iteration of interference cancellation is performed on the basis of bit rates for every signal which are the same as those in a previous frame of the same signal. Filtered and down-converted signals are demodulated in Rake receivers to provide output signals corresponding to decision variables and channel estimates. The decision variables are limited and remodulated and respread prior to the signals being reconstructed using the channel estimates. The reconstructed signals are summed, and each signal is subtracted from the sum to provide an ‘interference’ signal which is then used to obtain the individual signals. Each signal is then demodulated a second time in another Rake receiver to provide a tentative DPDCH signal, a TFI signal, a TPC signal and a SNI signal.

Abstract: The invention relates to a switching device (300) having a plurality of line interface cards (LICs) (310), a plurality of egress LICs (320), a cross-bar (330) and a management card (340). The switching device (300) routes fixed sized cells of data across the cross-bar (330). The cells comprise fragments of variable length data packets. Each ingress LIC (312, 314, 316) is associated with a respective schedule or timetable (362, 364, 366) governing the transmission of cells by the ingress LIC. Similarly, each egress LIC (322, 324, 326) is also associated with a respective schedule or timetable (382, 384, 386) governing the reception of cells by said egress LIC. The schedules are in the form of a table whose entries are the identities of transmission queues corresponding to a respective egress LIC identification number (for ingress LICs) and ingress LICs from which to receive (egress LICs). Each ingress and egress LIC maintains a pointer into its associated schedule.

Abstract: When transmitting bursty data, for example packet data, a mobile terminal uses information relating to signal strength at the base station to determine the power at which the mobile terminal must transmit in order to produce a required signal to noise ratio at the base station. In frequency division duplex techniques, multi-path fading on the down-link is uncorrelated with multi-path fading on the up-link. Power measurements can be averaged at the mobile terminal over a likely fading period. However, this does not cater for instantaneous power level fluctuations in the up-link direction, which can result in the power transmitted by the mobile terminal being too high or too low at the start of a frame. The invention maintains a predetermined signal to noise ratio. At a given time slot, a power level is determined which, over remaining time slots, is based on the sum of power levels corresponding to previous time slots and the number of time slots remaining in the frame.

Abstract: A system for controlling the demultiplexing process in an optical backplane device has application to optical switching in high-speed digital communication routers and switches. In demultiplexing, a selected compressed data packet is extracted from a multiplexed stream of compressed packets by a modulator and decompressed. The modulator is controlled by a control signal. An error in the timing of the modulator control signal corresponds to a characteristic distortion in the decompressed signal. By monitoring the effect of timing errors on decompressed signals, steps can be taken to correct the timing errors by controlling delays in either the optical or the electronic parts of the switching device. The timing of modulator control pulses is thus continuously adjusted to minimize timing errors. Instead of monitoring just decompressed signals, calibration pulse trains of known value and suitable form can be inserted.

Abstract: A method for deploying a reconnaissance sonde, including the steps of: incorporating at least one environmental sensor and an associated communication device into a robust, aerodynamically efficient casing; deploying the sonde by imparting a spin and a directional velocity to the casing, sufficient to carry the sonde into a region of interest; and establishing communication with the communication device, thereby enabling data from the sensor(s) to be transmitted to a remote location. A sonde for remote data collection is also provided, including at least one environmental sensor, an energy source and communication means. The sonde is generally shaped as a discus or saucer, a clay pigeon or skeet, for deployment by applying a spin and directional velocity to the sonde.

Abstract: A method for operating an autonomous vehicle at an airport comprises the steps of: receiving a set of general purpose navigation signals; receiving a supplementary set of navigation signals; receiving constraint data representing a permitted area of operation; calculating a present position of the vehicle; comparing the calculated present position of the vehicle with the constraint data, thereby to determine whether the vehicle's present position lies within the permitted area; and producing a signal indicative of the result of said comparing step. The autonomous vehicle for use at an airport, comprising: a navigation processor for calculating a present position of the vehicle; a constraint store for storing constraint data indicating a permitted area of operation; navigation receivers for receiving general purpose navigation signals and supplementary navigation signals, for guiding aircraft to land at the airport; and a comparator for comparing the constraint data with the present position.

Abstract: Apparatus for producing an amplified Radio Frequency pulse includes a controller for monitoring the output amplified pulse and determining therefrom a correction for a deviation in the characteristics. The correction is applied by a phase shifter or amplitude controller for subsequent pulses. The apparatus is particularly applicable to pulses used by RADAR equipment and allows the use of longer duration pulses. This improves the detection range of the equipment.

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) 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).

Abstract: The present invention provides methods and apparatus for optimising power consumption in transistor amplifiers. The method comprises the step of adapting the amplifier characteristics of the transistor by adapting the bias impedance at the base of the transistor. The method may further comprise the step of adapting the amplifier characteristics of the transistor by adapting the quiescent collector current in the transistor.

Abstract: The bias circuit of the present invention can be configured for extremely stiff biasing for Class A circuits, which is solid under heavy RF input overdrive. Alternatively, the circuit may be configured for controlled self biasing for use in Class AB designs.

Abstract: A method and apparatus are described for controlling the operation of an amplifier, in which, a bias level applied to the amplifier is adjusted so as to generate an output signal having the desired level of peak to mean ratio.

Abstract: A passive object detection system (1) comprises first and second antennas (4, 6) and a processor (8). The first antenna (4) is adapted to receive a signal transmitted by a mobile telephone base station; the second antenna (6) is adapted to receive the signal transmitted by a mobile telephone base station (2) after it has been reflected off an object (3) and the processor compares the signal received from the mobile telephone base station with the signal reflected from the object to derive speed or position information relating to the object therefrom.

Abstract: A method of tracking the position and orientation of an ultrasound beam emitted from an ultrasound probe. The method includes the steps of storing a model of the visible object in a memory of an optical tracking system; calculating the position and orientation of the visible object; and calculating the position and orientation of the ultrasound beam by applying a known geometric relationship to the deduced position and orientation of the visible object.

Abstract: An analog to digital converter (ADC) includes a comparator, N×1-bit clocked shift register and a clock which is phase-locked to the input signal. The system according to the invention includes such an ADC, together with processing means. The ADC samples an input waveform and the processing means determines a correction waveform, converts the correction waveform to an analog signal, combines the correction waveform with the input waveform to control its envelope and outputs a combined waveform. The combined waveform is substantially flat.

Abstract: Method and apparatus for providing accurately synchronised timing signals at mutually distant locations employs a GPS or similar receiver at each location. These receivers are interconnected by a communications network, and exchange data over the network to agree a common timing reference.

Abstract: A cellular communications system comprises a plurality of base stations serving respective system cells, each base station being capable of communicating with a plurality of mobile terminals within its cell and with at least some mobile terminals in adjacent system cells. Where connection of a mobile terminal to one of the base stations demands the downloading of information that, combined with data already being handled by that base station, would place excessive load on the data-handling capability of the base station, the data transmission is shared by that base station and at least one other. By this means, a call requesting the downloading of significant amounts of data, placed by a mobile terminal upon a base station that is already heavily loaded with data transmissions to other mobile terminals, is dealt with in parallel by two or more base stations, so that individual base loading is substantially reduced.

Abstract: An automobile radar which serves to provide data for cruise control or other systems in a host vehicle, comprising means for measuring radar boresight misalignment by detecting the presence of apparent variations in the spacing of stationary objects from the direction of motion of the host vehicle and utilizing such detection to compensate for any misalignment.

Abstract: Described herein is a method for reassembling variable length packets from fixed length cells. When a variable length packet, for example, an Internet Protocol (IP) packet, is transmitted between routers over a link which transmits data as fixed length cells, for example, an asynchronous transfer mode (ATM) link, the packet must be segmented into compatible fixed length cells. The receiving router must reassemble the original packet from the cells as they arrive. A packet buffer free pool (300) is provided which is maintained as a linked list, known as a ‘free list’, and which comprises a plurality of buffer elements (302, 304, 306, 308, 310, 312, 314, 316, 318, 320, 322, 324, 326, 328, 330, 332, 334, 336, 338, 340). When a first cell for a given packet arrives, a buffer element (302) is taken from the head of the free list and allocated to that packet.