Vector tracking loop operability through oscillator micro-jump event

摘要

A navigation system comprises a GNSS receiver that receives GNSS signals on multiple tracking channels, an INS that generates inertial data, and a processor. A micro jump detection and correction module comprises an oscillator micro jump detector that monitors estimates of C/N0 in all tracking channels, and detects a micro-jump event when there is an abrupt decrease of C/N0 in all tracking channels. An offsets module defines a plurality of carrier NCO command offsets to search over signal Dopplers in all available tracking channels after the micro jump event is detected, and sends the carrier NCO command offsets to the GNSS receiver to be added to nominal carrier NCO commands. The micro jump detector selects a tracking channel with the highest C/N0 after carrier NCO command offsets are added to nominal carrier NCO commands, computes corrections for clock error estimates, and sends the corrections for the clock error estimates to a GNSS/inertial Kalman filter.

主权项

1. A navigation system, comprising:
a global navigation satellite system (GNSS) receiver configured to receive multiple GNSS signals on a plurality of signal tracking channels; an inertial navigation system (INS) configured to generate inertial data; a processor in operative communication with the GNSS receiver and the INS; and a micro jump detection and correction module in operative communication with the processor and comprising:
an oscillator micro jump detector configured to:
monitor estimates of carrier to noise density (C/N0) ratios in all of the signal tracking channels; anddetect onset of a micro jump event when there is an abrupt decrease in the C/N0 ratios in all of the signal tracking channels;a carrier numerically controlled oscillator (NCO) command offsets module in operative communication with the micro jump detector and configured to:
define a plurality of carrier NCO command offsets to search over signal Dopplers in all available signal tracking channels after the micro jump event is detected; andsend the carrier NCO command offsets to the GNSS receiver to be added to nominal carrier NCO commands; wherein the micro jump detector is further configured to:
select a signal tracking channel with the highest C/N0 ratio after the carrier NCO command offsets are added to the nominal carrier NCO commands;compute corrections for clock error estimates; andsend the corrections for the clock error estimates to a GNSS/inertial Kalman filter.