Abstract: Techniques are provided herein for the offline static analysis of a stable code base in order to build a compiler and tools specialized to that code base. This allows global code base knowledge to be applied earlier in the compilation process giving better opportunities for optimization. The offline static analysis produces specialized compiler components that are then used to rebuild the compiler. This results, over time, in a compiler specialized to the code base with improved optimization after every compiler release cycle.

Abstract: A signal receiver is arranged to process a portion of a received signal in each of a plurality of filter branches and to determine a quality metric for each branch. The configuration of a second filter for processing the entirety of the received signal is subsequently performed according to the determined quality metrics.

Abstract: A method of evaluating the usage in a received signal of codes from a tree of codes that can be used to orthogonalise communications signals, the method including testing to determine if a given code is in use in the received signal and deducing from the result and from the tree structure the need to test in the received signal for the use of the codes in the portion of the tree depending from said given code. The invention also includes corresponding apparatus and software.

Abstract: Apparatus arranged to analyse a signal comprising a series of symbols, the apparatus comprising means for calculating a metric of said signal, filter means for filtering said signal, means for calculating a metric of said filtered signal and means for comparing said metrics, wherein the filtering means is arranged to track a spectral feature of the signal and maintain that feature within the pass band of the filtering means.

Abstract: A method of calculating backward computations branch metrics for a butterfly in a trellis of a MAP-genre decoding algorithm includes providing initialized branch metrics for the transitions in the butterfly and incrementing the branch metrics with a group of data values corresponding to the transitions in accordance with control signals derived from the butterfly index and one or more polynomials describing tap positions of the encoding equipment to whose operation the trellis relates, wherein the group comprises systematic bit and parity bit values.

Abstract: A communications signal is received through a propagation channel, down-converted in frequency and then converted into a digital signal. The samples of the digital signal are processed to estimate the information conveyed by the communications signal. The estimated information is then used with knowledge about the propagation channel to model the samples of the digital signal. The modeled samples are compared with actual samples of the digital signal to deduce phase errors in the digital signal. The phase errors are then used to deduce a frequency error in the digital signal that can be used to correct the samples of the digital signal and to correct the down-conversion process.

Abstract: A method is provided of characterising a data stream of binary symbols, the method comprising sampling the stream at a predetermined rate sufficient to capture at least two samples per binary symbol, identifying the shortest continuous run of samples having the same logic level and assigning a symbol rate to the stream on the basis that the identified run is one symbol in length.

Abstract: A scheme for deducing a DC offset in a received signal burst acquired through a particular channel, wherein the received signal burst corresponds to a transmitted signal burst. An impulse response estimate of the channel is used to model how a known or recovered part of the transmitted burst would have been affected by passage through said channel in place of the corresponding part of the transmitted signal burst. The modelled part of the transmitted burst is then compared with the corresponding part of the received signal burst to deduce a DC offset present in the received signal burst.

Abstract: A telecommunications network participant, comprising means for digitising, as a series of samples, a received signal containing a succession of symbols, means for measuring time misalignment between the symbols and the samples and means for applying a fractional delay to the positions of the samples to reduce the misalignment.

Abstract: The mixed signal chip (10) takes analogue signals received at, for example, a mobile telephone and converts them to the digital domain for subsequent processing. Through use of sample rate adaption and adjustable filtering, the mixed signal chip can work on radio signals formatted according to different standards.

Abstract: A method and processor for recovering a plurality of individual data streams from a composite data stream The composite data stream having been formed by first bit reordering the individual data streams with respect to themselves, combining the individual data streams and second bit reordering the combined individual data streams to form the composite data stream. The processor is arranged to for a current bit position in the composite data stream perform the steps of: (a) applying an inverse of the second bit reordering; (b) identifying to which individual data stream the current bit belongs; (c) storing the current bit in a memory space allocated to the identified individual data stream wherein the current bit is positioned within the memory space according to the first bit reordering; and performing steps (a) to (c) for each bit position in the composite data stream.

Abstract: A wireless-communications unit has a receiver chain including a codec decoding the output of a rake receiver. Soft decisions passing from the rake receiver to the codec are scaled. The scaling factor can be tuned by monitoring a function based on the cumulative probability distribution function of the scaled soft decisions.

Abstract: Multiple data devices (A,B,C) are interfaced via a bus arbiter (S) with an external memory (F) so as to support burst-mode access by each device (A,B,C) one or more read registers (R1,R2,R3) are provided in the memory (F), and each register (R1,R2,R3) supports burst-mode access by a corresponding device (A,B,C). The arbiter (s) selects the register to be used following the initial access burst, according to the device requiring access. Thus, the memory (F) supports multiple burst-mode accesses in parallel.

Abstract: An interrupt controller (1) is adapted to control the execution of interrupt requests (11, 12) of differing criticality by a processor (7) which is required to execute tasks (3, 17) of differing criticality under the control of a computer operating system (5); the interrupt controller being adapted to recognize critical (11) and non-critical (12) interrupt requests originating from different interrupt sources, and to recognize when the processor (7) is required to execute each of critical (3) and non-critical tasks (17); the interrupt controller being further adapted to pass critical interrupt requests (11) to the processor (7) for execution in preference to non-critical interrupt requests (12), to block non-critical interrupt requests (12) to the processor when they coexist with critical interrupt requests (11) or the processor (7) is required to execute critical tasks (3), and to pass non-critical interrupt requests (12) to the processor (7) when they do not coexist with any critical interrupt requests (11)

Abstract: A wireless communications network participant comprising: a plurality of communications subsystems, each subsystem being arranged to transmit and/or receive signals under a different telecommunications standard; means for generating a clock signal; and scheduling means for sending commands to at least one of the subsystems for its or their operation, the scheduling means deducing the timing of the commands relative to the clock signal.

Abstract: A method of assessing an encoded signal to determine whether a candidate format was used to arrange the signal into blocks before the encoding was done, the method comprising: using the Viterbi algorithm to determine trellis metrics for a point in said signal that would be an end point of a candidate block according to the candidate format; determining from said metrics the likelihood of occupation at said point of an end state of an encoding scheme used to create the encoded signal; decoding a part of said signal ending at said point; and performing a check using said decoded part to determine whether the candidate block satisfies an error protection scheme of the candidate format.

Abstract: A method for applying one or more code values to an input signal value to produce an output signal value in a CDMA communications scheme, wherein the code value or values may lie only either on or equally distant from an orthogonal pair of axes defining a two dimensional signal space, the input and output signal values each have components along each axis and the method comprises processing, via a logic function, the code value or values to produce two multiplier values and a selector value, creating two product values by multiplying the multiplier values with respective components of the input signal value, negating one of the product values to produce a third product value and selecting, on the basis of the selector signal, two of the three product values to become the components of the output signal value.