Olympus Corporation

Denis A Gudovskiy

Lichung Chu

Shinhaeng Lee

An improved sliding discrete Fourier transform (SDFT) algorithm called CIC-SDFT and its apparatus are provided. An input signal is multiplied by a modulated twiddle factor, and is then processed by a modified cascade integrator-comb (CIC) filter. The CIC-SDFT comprises an integrator section and a comb section, with a downsampler disposed between the two sections to enable downsampling of the SDFT computations. Through addition of more integrator stages and comb stages to the CIC-SDFT, the accuracy of spectrum estimation may be improved in a computationally inexpensive manner and with less complexity than applying windowing functions to known SDFTs. Various embodiments provide a partially-nonrecursive method of CIC-SDFT that further decreases computational complexity.

Method and apparatus for accurate and efficient spectrum estimation using improved sliding DFT

Systems and methods are provided in which a wireless receiver can be configured to digitally synchronize a receive sampling rate to a transmit sampling rate, and may include a digital interpolator controlled by a timing control unit with a timing offset estimator. The timing control unit can be configured to calculate and output parameters to the digital interpolator. The digital interpolator can include a sample buffer followed by a fractional delay filter. Output parameters to the digital interpolator can include a fractional delay timing offset signal of the receiver relative to a transmitter timing signal and a buffer pointer control signal to control a position of the read pointer relative to a write pointer to compensate for subsample timing offset. The timing offset estimator can be configured to calculate and provide to the timing control unit a sampling period ratio control word and an instantaneous timing offset control word.

Sampling rate synchronization between transmitters and receivers

Systems and methods are provided in which a wireless receiver can be configured to compensate frequency and phase offsets with joint symbol timing recovery of modulated signals transmitted across a channel, and it can include a transformation module configured to generate an error signal for an information signal representing the modulated signal received by the receiver. The transformation module can include a squaring module configured to square the information signal, thereby generating a squared signal, and a mixer configured to perform a complex multiplication of the squared signal by the local reference signal, and a downsampler. The transformation module can also be configured to extract and compensate frequency and phase offsets with joint symbol timing recovery.

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San Diego, CA, United States of America

Denis A Gudovskiy