Common Coordinate-Quartz Loop for Reducing the Impact of Shock and Vibration on Global Navigation Satellite System Measurements

摘要

A navigation receiver operably coupled to an antenna can determine location by receiving and processing radiofrequency navigation signals from global navigation satellites.;The navigation receiver includes a quartz crystal oscillator that serves as a reference frequency source for a local oscillator signal that is mixed with the radiofrequency navigation signals to generate intermediate signals at intermediate frequencies lower than the radiofrequencies.;In particular applications, the quartz crystal oscillator and the antenna are subjected to vibration and shock.;A shift in the frequency or phase of the intermediate signals can result, and performance of phase-lock loops can degrade.;Performance is improved with a phase-lock loop that processes a combination of individual channel control signals and common control signals.;The common control signals are generated by a common coordinate-quartz loop discriminator that processes signals generated from the entire group of navigation signals received by the navigation receiver.

主权项

1. A method for improving the performance of a navigation receiver operably coupled to an antenna, wherein the navigation receiver and the antenna are subjected to vibration and shock, and wherein the navigation receiver comprises a quartz crystal oscillator generating a quartz crystal oscillator signal having a quartz crystal oscillator frequency, the method comprising the steps of:
receiving a plurality of navigation signals, wherein each individual navigation signal in the plurality of navigation signals corresponds to an individual global navigation satellite in a plurality of global navigation satellites, and wherein each individual navigation signal in the plurality of navigation signals has a corresponding radiofrequency; generating a local oscillator signal having a local oscillator frequency, wherein the local oscillator signal is based on the quartz crystal oscillator signal, and wherein the local oscillator frequency is based on the quartz crystal oscillator frequency; generating a plurality of intermediate signals based on the plurality of navigation signals and based on the local oscillator signal, wherein each individual intermediate signal in the plurality of intermediate signals corresponds to an individual navigation signal in the plurality of navigation signals, and wherein each individual intermediate signal in the plurality of intermediate signals has a corresponding intermediate frequency based on a difference between the corresponding radiofrequency and the local oscillator frequency; generating a plurality of sequences of digital signals, wherein each individual sequence of digital signals in the plurality of sequences of digital signals corresponds to a digital representation of an individual intermediate signal in the plurality of intermediate signals; and for each individual sequence of digital signals in the plurality of sequences of digital signals, tracking a phase of the individual sequence of digital signals with an individual channel phase-lock loop, wherein the step of tracking the phase of the individual sequence of digital signals with an individual channel phase-lock loop comprises the steps of:
generating, with an individual channel correlator operating at a first clock frequency, a sequence of in-phase correlation signals and a sequence of quadrature-phase correlation signals, wherein the sequence of in-phase correlation signals and the sequence of quadrature-phase correlation signals are based on the sequence of individual digital signals and based on a sequence of individual channel reference signals received from an individual channel numerically-controlled oscillator;generating, with a common coordinate-quartz loop discriminator operating at a second clock frequency, a sequence of common control signals;generating, with an individual channel accumulator operating at a third clock frequency, a sequence of accumulated in-phase correlation signals and a sequence of accumulated quadrature-phase correlation signals, wherein the sequence of accumulated in-phase correlation signals is based on the sequence of in-phase correlation signals, and wherein the sequence of accumulated quadrature-phase correlation signals is based on the sequence of quadrature-phase correlation signals;generating, with an individual channel discriminator operating at the third clock frequency, a sequence of phase-lock loop tracking error signals based on the sequence of accumulated in-phase correlation signals and based on the sequence of accumulated quadrature-phase correlation signals;generating, with an individual channel loop filter operating at the third clock frequency, a sequence of individual channel control signals; andgenerating, with the individual channel numerically-controlled oscillator, wherein the individual channel numerically-controlled oscillator operates at a fourth clock frequency, the sequence of individual channel reference signals, wherein the sequence of individual channel reference signals is based on the sequence of common control signals and based on the sequence of individual channel control signals; andtransmitting the sequence of individual channel reference signals to the individual channel correlator.