U-blox Ag

Michael Ammann

Andreas Thiel

Heinz Mathis

A satellite positioning receiver. The receiver comprises: an RF front end, for receiving satellite positioning signals; an analog to digital converter, for sampling the received signals to generate signal samples; a memory; and a processor, for processing the signal samples to derive code-phases and pseudo-ranges and to calculate a position fix. The processor has a first mode in which it is operable to process the samples as they are generated, to calculate the position fix. It also has a second mode in which it is operable to store the samples or the code-phases or pseudo-ranges in the memory for later processing.

Hybrid satellite positioning receiver

An acquisition unit of a GNSS receiver base band circuit includes an integrator with a number of preprocessors where an incoming digital signal is mixed with different frequency signals to compensate at least in part for clock drift and Doppler shifts. The resulting digital signals are, after an accumulation step reducing sample frequency, integrated over an integration period extending over several basic intervals of the length of a basic sequence characteristic for a GNSS satellite, so that samples separated by a multiple of the basic interval are superposed. The resulting data sequence of 1,023 digital values is stored in one of two memories and then, in mixers, sequentially shifted by post-integration frequencies which are multiples of the inverse of the length of the basic interval. The pre-integration frequencies employed in the preprocessors deviate, with one possible exception, from the post-integration frequencies and are usually smaller.

Method of processing a digital signal derived from an analog input signal of a GNSS receiver, a GNSS receiver base band circuit for carrying out the method and a GNSS receiver

In a GNSS receiver data sequences derived from a digital signal each with an internally generated correlation sequence derived from a basic sequence and mixed with frequency signals corresponding to various Doppler frequencies and in various phase positions with respect to the data sequence are correlated and the correlation values evaluated. In difficult conditions, e.g., RF levels of the signal of &#x2212;145 dBm and less, correlation values produced with the same correlation sequence and phase position but with a plurality of data sequences are evaluated together in that, in an evaluator (), every-correlation value is, in a comparator (), compared with at least a first value threshold and a second value threshold, with the latter having a value between 1.3 and 1.7 times the value of the first and values &#x2212;1, 0 or +1 assigned accordingly to a correlation term which is then added to an integer correlation counter which varies over a counter interval, e.g., [0, 15], in an adding unit (). The correlation counters corresponding to the various Doppler frequencies and phase positions are stored in a memory unit (). In an arbitration unit () a correlation indicator is derived from each correlation counter and the latest corresponding correlation value and the six largest correlation indicators selected and stored together with their Doppler frequencies and phase positions.

Method of processing a digital signal derived from a direct-sequence spread spectrum signal

An acquisition unit of a GNSS receiver base band circuit includes an integrator with a number of preprocessors where an incoming digital signal is mixed with different frequency signals to compensate at least in part for clock drift and Doppler shifts. The resulting digital signals are, after an accumulation step reducing sample frequency, integrated over an integration period extending over several basic intervals of the length of a basic sequence characteristic for a GNSS satellite, so that samples separated by a multiple of the basic interval are superposed. The resulting data sequence of 1,023 digital values is stored in one of two memories and then, in mixers, sequentially shifted by post-integration frequencies which are multiples of the inverse of the length of the basic interval, The pre-integration frequencies employed in the preprocessors deviate, with one possible exception, from the post-integration frequencies and are usually smaller.

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Huenenberg, Switzerland

Michael Ammann