O2micro International Limited

02 Micro International Limited

Maishi Electronic (shanghai) Ltd.

MingQiang Cheng

Bo Yu

ShiJie Li

Cheng Li

Jianhui Hou

Xiquan Yang

Yi Zeng

An apparatus for processing spread spectrum signals is disclosed. The apparatus includes an intermediate frequency (IF) signal preprocessing unit, which includes a first set of multiply-accumulator (MAC) units and a second set of MAC units. The IF signal preprocessing unit generates a first and a second set of data streams using a digitized signal and a first and second local reference signals respectively. Each data stream is generated every predetermined time period, and each data stream includes pre-integration results generated at a predetermined rate.

Parallel correlator implementation using hybrid correlation in spread-spectrum communication

The present invention is a method for GPS positioning in a weak signal environment. The method includes obtaining assistance data for a GPS signal from a satellite at a predetermined time, wherein the assistance data including predicted navigation data, Doppler shift and Doppler shift rate and the GPS signal being modulated by a carrier signal, a pseudorandom code and navigation data, estimating a predicted receiving time for the GPS signal reaching the GPS receiver, capturing the GPS signal, converting the GPS signal to an intermediate frequency signal, acquiring a code phase of the pseudorandom code from the intermediate frequency signal by using the assistance data and the predicted receiving time, and obtaining a position for the GPS receiver based on the predicted navigation data and the code phase of the pseudorandom code. To acquire the code phase of the pseudorandom code, the GPS receiver corrects a real time clock to one millisecond accuracy and process the intermediate frequency signal through coherent correlation of one second.

Method for GPS positioning in a weak signal environment

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. The peak value is regarded as a signal power value, while the averaged non-peak values are regarded as an average noise power value. A signal-to-noise ratio is then calculated based on the signal power value and the average noise power value. A method for determining the parameters for the tracking loop is also provided. The method includes estimating the signal-to-noise ratio of the spread spectrum signal, and determining the tracking loop parameters based on the signal-to-noise ratio.

Apparatus and method for determining GPS tracking loop parameter based on SNR estimation

An apparatus for processing spread spectrum signals digitized at a predetermined sampling frequency. The apparatus includes an intermediate frequency signal preprocessing unit, a plurality of parallel block integrators. The intermediate frequency signal preprocessing unit is capable of generating pre-integration results based on an input signal and local reference signals at a predetermined rate. The pre-integration results produced by the intermediate frequency signal preprocessing unit are grouped into sets of pre-integration results. Each set of the pre-integration results contains a predetermined number of pre-integration results. The plurality of parallel block integrators is in communication with the intermediate frequency signal preprocessing unit. Each of the block integrators is capable of receiving, in succession, sets of a predetermined number of pre-integration results, and for each set of predetermined number of pre-integration results, each of the block integrators is capable of performing a plurality of partial correlations based on the set of the predetermined number of pre-integration results and a plurality of shifted segments of a pseudorandom noise code until a next set of pre-integration results are received by the block integrator.

Parallel correlator implementation using block integration for spread-spectrum communication

A method for processing spread spectrum signals through a two step integration process in a circuit having an intermediate frequency signal preprocessing unit and a plurality of block integrators, wherein the circuit receiving a digitized signal, a local reference signal, and a pseudorandom noise code. The method includes generating a plurality of data streams by the intermediate frequency signal preprocessing unit using the digitized signal and the reference signal, receiving at each block integrator a data stream from the plurality of data streams and the pseudorandom noise code, performing a predetermined number of partial correlations at each block integrator using hybrid correlation technique based on the data stream and the pseudorandom noise code to obtain a predetermined number of partial correlation results, and computing a predetermined number of complete correlation results based on the predetermined number of partial correlation results. Each data stream is generated every predetermined time period.

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Chengdu, China

MingQiang Cheng