Conexant Systems, Inc.

Discovision Associates

Other

Trident Microsystems (far East) Ltd.

Jonathan Parker

Matthew James Collins

David Huw Davies

Peter Keevill

Thomas Foxcroft

John Matthew Nolan

Dawood Alam

Anthony Peter Claydon

A receiver circuit processes a received signal to determine information regarding a guard interval therein. The receiver circuit typically forms digital samples from the received signal; generates a correlation function with peaks at positions that are determined by the size of the guard interval and a position of the guard interval within the received signal. The receiver circuit includes one or more comb filters, each corresponding to a possible guard interval size, each receiving a series of locations at which the correlation function exceeds a predetermined threshold, and each producing an output that provides information about the guard interval size and/or position. This advantageously allows the receiver circuit to determine the guard interval size quickly, for example, even in the case of received signals with relatively low signal-noise ratio.

Guard interval analysis method and apparatus

A method and apparatus for a demodulator circuit in a communication system is described. The invention relates to a demodulator circuit in a communication system using a multi-carrier modulation scheme. The demodulator makes efficient use of channel state information for respective carriers in the multi-carrier modulation to de-map the received data. An efficient method of calculating channel state information is also disclosed.

Method and apparatus for a demodulator circuit

A method and apparatus for receiving radio frequency signals in a communication system is described. The inventive method and apparatus utilizes an inventive receiver circuit that downconverts an input signal so that interference components of the input signal can be easily removed at baseband. Specifically, the inventive receiver circuit operates by sub-sampling a first intermediate frequency signal in such a way that an unwanted signal is not aliased into a wanted signal, and can therefore be filtered therefrom after sub-sampling. Thus, the present invention allows the use of a relatively simple tuner, with a single downconversion stage, without imposing excessive requirements on the filtering in the tuner.

Method and apparatus for receiving radio frequency signals

A method and apparatus that identifies the degree of correlation between a demodulated in-phase (I) and quadrature (Q) signal that represents phase imbalance between the in-phase (I) and quadrature (Q) signal and corrects the imbalance.

Method and apparatus for correcting phase imbalance in received in-phase and quadrature signals

The invention provides a single chip implementation of a digital receiver for multicarrier signals that are transmitted by orthogonal frequency division multiplexing. Improved channel estimation and correction circuitry are provided. The receiver has highly accurate sampling rate control and frequency control circuitry. BCH decoding of tps data carriers is achieved with minimal resources with an arrangement that includes a small Galois field multiplier. An improved FFT window synchronization circuit is coupled to the resampling circuit for locating the boundary of the guard interval transmitted with the active frame of the signal. A real-time pipelined FFT processor is operationally associated with the FFT window synchronization circuit and operates with reduced memory requirements.

Single chip VLSI implementation of a digital receiver employing orthogonal frequency division multiplexing

A method and apparatus are disclosed for determining the boundaries of guard intervals of data symbols being received in a coded orthogonal frequency division multiplexed signal. Temporal samples separated by an interval of an active interval of a data symbol are associated in pairs, and difference signals obtained. The dispersion of a first comparison block of difference signals is determined, and compared to the dispersion of a second comparison block of difference signals, the second comparison block being displaced from the first comparison block by n samples. An F ratio is calculated for the dispersions of the two blocks. F ratios are iterated in a succession of comparison blocks, and a signal representing the F ratios subjected to peak detection. The peaks represent the boundaries of the symbol's guard interval. This information is utilized in synchronizing an FFT window for subsequent signal reconstruction.

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Bath, United Kingdom

Jonathan Parker