Abstract: A multi-bit continuous-time sigma-delta analog-to-digital converter provides a digital output signal as a digital representation of an analog input signal. The converter performs several functions in providing the digital output signal. First, the converter provides an analog summing signal indicative of a summation of the analog input signal and an analog feedback signal. Second, the converter provides a first set of bits as a digital representation of the analog summation signal. Third, the converter provides a second set of bits as a digital representation of a periodic sampling of the first set of bits. Fourth, the converter provides the analog feedback signal as an analog representation of the second set of bits. Fifth, the converter outputs the first set of bits or the second set of bits as the digital output signal.

Abstract: The invention provides a method for operating a hybrid automatic repeat request communication system wherein it is determined whether a receiver can process a data packet, and a self-decode request associated with the data packet is sent based on the determination.

Abstract: A method for reducing blurring associated with objects forming part of a grey scale image. The method includes receiving (11) a set of image pixels and then calculating (12) a gradient value for each one of the image pixels in the set. A selecting step (13) selects candidate object edge pixels from the image pixels by comparing the gradient value for each one of the image pixels in the set with a threshold value. A determining step (14) then determines a distribution of number candidate object edge pixels with specific grey level values. Thereafter, candidate object edge pixels within said distribution that have the same grey level values are identically non-linearly modified at a modifying step 15.

Abstract: In a method for channel equalization a communications receiver receives an input data stream comprising modulation symbols. A reduced set sequence estimation algorithm produces intermediate hard decisions, based on the input data stream and on a channel reference, which are applied to a decision feedback filter in a feedback loop. Soft output sequences of emitted symbols are also produced, based on the input data stream, which are decoded, error-corrected and re-encoded. The error-corrected soft output sequences are iteratively applied to the decision feedback filter, such that a channel equalized received data stream is generated based on both the feedback soft output sequences and the intermediate hard decisions. An iterative decision-aided equalizer is also described. In this manner, errors corrected by the decoder are not re-introduced into the decision feedback filter, hereby reducing the effect of error propagation in decision-aided feedback equalizers.

Abstract: A sub-Walsh element generator (30) partitions incoming Walsh codes into sub-elements (201-212). A sub-element generator (30) determines if a pair of Walsh sub-elements (201-212) exist at a boundary (401) between Walsh codes (101-102), and if so, the pair of sub-elements is output to a phase difference operator (40). The phase difference operator (40) determines a change in phase between the two consecutive sub-elements that exist at the Walsh code boundaries. The phase difference metric (45) is further accumulated over a predetermined period of time and is utilized to adjust a front-end frequency of a receiver.

Abstract: In accordance with the preferred embodiment of the present invention, excess power is distributed to certain streams in order to increase the stream's signal quality, and thus, its encoding rate. Although certain streams will have their overall power, and thus their signal quality reduced, in the preferred embodiment of the present invention the reduction in signal quality is limited so that the encoding rate for these streams remains unchanged.

Abstract: A method and apparatus for quantising data in a data compression system (1) involves receiving original data (2) in the form of a plurality of discrete data values. A plurality of quantisation techniques (11, 14) including bitplane and uniform quantisation techniques are provided in the data compression system (1), at least one of which is selected for quantising the received data. The received data is quantised using one or more of the selected techniques, for example, firstly using the bitplane technique and then using the uniform quantisation technique on the results of the bitplane to produce quantised data, which is then output (6).

Abstract: A communication system employs a HARQ-type retransmission scheme. Bits (701) received on a first transmission are stored and combined with the bits received on later transmissions thereby increasing the likelihood of a correct decoding on later transmissions. Similarly the bits received on the second or later transmissions are stored for combining with subsequent received bits. Specific information needed at the receiver is identified and requested from the transmitter. More particularly, information that is retransmitted in a second or later transmission in the HARQ scheme is determined from a reliability of individual constituent bits in the mother codeword or from an overall reliability of the received codeword. Based on these reliability metrics, the most unreliable set of the constituent bits are requested or, in the alternative, a specific number of constituent bits is requested.

Abstract: The invention provides a method for generating a code sequence. A code-generation instruction is received from memory. One or more control signals are determined based on the code-generation instruction. A code sequence is generated based on the control signals, a current state input, and a mask input.

Abstract: The invention provides a method of coding an information signal. An information signal is represented by a sequence of pulses. A plurality of pulse parameters are determined based on the sequence of pulses including a non-zero pulse parameter corresponding to a number of non-zero pulse positions in the sequence of pulses. The non-zero pulse parameter is coded using a variable-length codeword.

Abstract: The invention is a method of estimating the time and frequency response of at least one desired signal received by at least one antenna, based on Gradient Optimization techniques. Through the use of gradient optimization techniques and efficient DFT processing, the invention provides frequency response estimates that require fewer computations than prior art decision-directed channel estimation devices.

Abstract: A voiced/unvoiced speech classifier (30) includes a speech segmentor (34) which segments an input digitized speech waveform into frames of speech and a band-pass filter (36) which filters the frames of speech. A relative energy generator (38) generates a relative energy value for each filtered frame of speech and a decision parameter generator (52) including an autocorrelation calculator (54) and a pitch calculator (56) generates a decision parameter based on an autocorrelation function and a pitch frequency index for the filtered frames of speech. A normalized energy calculator (46) adjusts the threshold and then normalizes the relative energy. A comparator (60) provides a signal indicative of whether a frame of speech is voiced speech or unvoiced speech depending on a comparison of the decision parameter and the normalized relative energy value for each filtered frame of speech.

Abstract: The invention provides a method of determining an adaptive channel estimation by providing a channel estimate, determining at least one channel condition, and determining an adapted channel estimate as a function of the channel estimate and the channel condition.

Abstract: An image compression system (1) having a wavelet transform module (3) for decomposing an input image subdivided into blocks using a wavelet transformation utilizes a statistics generator (7) to determine average statistics over several blocks to provide an indication of the activity of a current image block. This activity value is passed to a quantisation control module (8) which determines quantisation parameters for a quantisation module (4) which quantises the transform coefficients output from the wavelet transform module (3). The quantised transform coefficients are the coded for onward transmission or storage by coder (5). The quantisation control module (8) also receives bit rate information for the current image block from a rate monitoring module, which determines the bit rate for the current block from a desired bit rate and information on the number of bits used for the previous image block.

Abstract: Apparatus (10) for compensating for jitter in a digital image forming part of a video sequence of such digital images includes a first motion estimation unit (13) having an input for receiving sensed image data and an output for providing a first plurality of motion vectors, each corresponding to one of a plurality of image blocks making up the digital image. A jitter estimation unit (14) determines a jitter vector from the first plurality of motion vectors for the digital image and a jitter compensation unit (15) adjusts the digital image using the jitter vector to compensate for jitter in the digital image. A second motion estimation unit (16) provides a second plurality of motion vectors, each corresponding to one of a plurality of image blocks making up the jitter compensated digital image. The second plurality of motion vectors are determined by utilizing the first plurality of motion vectors and the jitter vector.

Abstract: A voltage (Vo) is added to an envelope function and input into a switching modulator (105). The output of the switching modulator (VSUP) is input to a linear regulator (103) where amplitude compensation of VSUP takes place and is output as VPA. VPA is then used to accomplish envelope modulation of a power amplifier (101). The value chosen for Vo is chosen to be adequate to maintain VSUP(t)>VPA(t) over all time.

Abstract: A voltage (Vo) is added to an envelope function and input into a switching modulator (105). The output of the switching modulator (VSUP) is input to a linear regulator (103) where amplitude compensation of VSUP takes place and is output as VPA. VPA is then used to accomplish envelope modulation of a power amplifier (101). The value chosen for Vo is chosen to be adequate to maintain VSUP(t)>VPA(t) over all time.

Abstract: A device for implementing a method for receiving a complex baseband signal in analog form or in digital form, and providing a pulse modulated signal as a linear modulation of the complex baseband signal is disclosed. First, a complex modulated signal as a function of the complex baseband signal is generated. Second, a bandlimited exponential signal as a function of the complex modulated signal as computed with a truncated Taylor series for an exponential is generated, or a coefficient vector as a function of the complex modulated signal is generated. Finally, a pulse modulated signal as either a function of the bandlimited exponential signal or the coefficient vector is generated.

Abstract: When a remote unit (113) accesses a cellular communication system (100) via an uplink communication signal (119), a Mobile Switching Center (104) notifies a voice-mail system (114) that the remote unit (113) is available for communication. The voice-mail system (114) then establishes a connection via a base station (102) and the downlink communication signal (116), to the remote unit (113). Once connection has been established between the voice-mail system (114) and the remote unit (113), the remote unit (113) downloads the voice-mail message from voice-mail system (114) for storage internal to the remote unit (113).

Abstract: An input sequence of unwarped signal samples is stored in an input buffer (101). A pitch and voicing analysis unit (103), which analyzes voicing classification data from the input buffer (101), provides a voicing classification variable indicating whether the voicing classification data is voiced or unvoiced and a preliminary estimate of the signal period in the interval spanned by the voicing classification data to a pitch pulse detection unit (104). The pitch pulse detection unit (104), also using analysis frame data from the input buffer (101), provides a set of locations of unwarped pitch pulses contained in the interval spanned by the analysis frame data to a mapping optimization unit (105). The mapping optimization unit (105) provides a set of parameters describing a mapping from an unwarped time-scale to a warped time-scale, to a warped sampling instant calculation unit (106).