In accordance with the present invention, the system and method removes interfering signals from a communications signal and includes a Fast Fourier Transform (FFT) circuit for taking the FFT of a received signal and segmenting the signal into segments. A frequency shifting circuit can shift each segment in frequency to place an interfering signal within a single FFT band to be later substantially nulled. An inverse FFT circuit can place the segments of signals back within the time domain.

A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characteriza...

A mirror suppression circuit includes a first quadrature signal path coupled between quadrature signal input and output terminals and an error correction circuit for correction of amplitude and phase errors in a carrier modulated quadrature signal. To obtain a suppression of both amplitude and phase imbalance of the carrier modulated quadrature signal as well as signal amplitude variations, a quadrature output of the error correction circuit is coupled to an error detection circuit. The error de...

A receiving unit (2) receives a modulated signal resulting from modulating a carrier signal with a digital encoded train resulting from error-correction encoding a digital signal train. A demodulating unit (4) demodulates the digital encoded train from the received modulated signal. A decoding unit (8) decodes the digital signal train from the demodulated digital encoded train. The receiving unit (2) outputs a received-signal strength indicative signal indicative of the received-signal strength ...

A method and a device for estimating the DC offset portion of a signal, especially of a signal containing parts with sinusoidal shape, for example a signal which results from demodulation of a frequency modulated receive signal. A method is presented for correcting the direct current offset portion (DC offset) of a first signal which includes phase shifting the first signal for obtaining a second signal and comparing the first signal and the second signal with an estimated DC offset. The estimat...

In accordance with the present invention, there are provided methods for estimating the level of interferers and the level of a useful signal in a spectral window of a given bandwidth in a communications channel in a complex multipath propagation environment. The first method of estimating the level of interferers comprises generating and transmitting several sets of sine waves on the Nyquist frequency. Each set is characterized by a certain phase so that the sequence of phase values evenly span...

A method/apparatus is provided that detects impairment in a received signal and employs the structure in the receiver that is designed for that purpose. Preferably, the method/apparatus detects the interferer modulation and employs the structure in the receiver that is designed for that purpose. The detection is preferably performed using a quality measure, e.g., the residual errors after channel estimation or SNR (signal-to-noise-ratio) estimates after channel estimation. Preferably, hypothesis...

A method for estimating signal quality of a spread spectrum signal is provided. The method includes squaring a plurality of in-phase correlation results and a plurality of quadrature correlation results, summing each squared in-phase correlation result and the corresponding correlation result to obtain a plurality of sum-of-square values, detecting a peak value among the plurality of sum-of-square results, calculating an average of non-peak values among the plurality of sum-of-square results. Th...

A computational algorithm provides new and effective interference cancellation of the in-band spurious signals for the Orthogonal Frequency Division Multiplex (OFDM) transmitters. This new interference cancellation transmits non-zero tones may be used to cancel the interference generated by the modulated data signals. This minimizes the number of tones used and maximizes the interference suppression achieved at the same time. The technique described is one of active interference cancellation (AI...

A circuit and method reduces noise signals coupled to a reference voltage used by a digital differential input receiver having an input that is coupled to an input/output terminal. The circuit and method selectively isolates the reference voltage from the input/output terminal to which output signals are selectively applied. The isolation occurs responsive to detecting that an output signal is being applied to the input/output terminal so that transitions of the output signal are not coupled thr...