VECTOR TRACKING LOOP OPERABILITY THROUGH OSCILLATOR MICRO-JUMP EVENT
First Claim
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; and
detect 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; and
send 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; and
send the corrections for the clock error estimates to a GNSS/inertial Kalman filter.
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Accused Products
Abstract
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.
19 Citations
20 Claims
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1. A navigation system, comprising:
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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; and detect 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; and send 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; and send the corrections for the clock error estimates to a GNSS/inertial Kalman filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for micro jump detection and resolution, the method comprising:
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monitoring estimates of carrier to noise density (C/N0) ratios in a plurality of signal tracking channels in a global navigation satellite system (GNSS) receiver that is integrated with an inertial navigation system (INS); determining whether any previous C/N0 ratio is greater than or equal to an upper threshold and whether all current C/N0 ratios are less than a lower threshold; detecting onset of an oscillator micro jump event in the GNSS receiver when any previous C/N0 ratio is greater than or equal to the upper threshold and all current C/N0 ratios are less than a lower threshold; assigning all available signal tracking channels different frequency command offsets to search over signal Dopplers in all available signal tracking channels after the micro jump event is detected; adding the frequency command offsets with nominal carrier commands in the GNSS receiver; selecting a signal tracking channel with the highest C/N0 ratio after the frequency command offsets are added to the nominal carrier commands; determining whether the highest C/N0 ratio is greater than or equal to the upper threshold; declaring the micro-jump event resolved when the highest C/N0 ratio is greater than or equal to the upper threshold; computing corrections for clock error estimates after resolution of the micro-jump event; and sending the corrections for the clock error estimates to a GNSS/inertial Kalman filter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A non-transitory computer readable medium including instructions executable by a processor to perform a method for micro jump detection and resolution, the method comprising:
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monitoring estimates of carrier to noise density (C/N0) ratios in a plurality of signal tracking channels in a global navigation satellite system (GNSS) receiver that is integrated with an inertial navigation system (INS); detecting onset of an oscillator micro jump event in the GNSS receiver when any previous C/N0 ratio is greater than or equal to an upper threshold and all current C/N0 ratios are less than a lower threshold; assigning all available signal tracking channels different frequency command offsets to search over signal Dopplers in all available signal tracking channels after the micro jump event is detected; adding the frequency command offsets with nominal carrier commands in the GNSS receiver; selecting a signal tracking channel with the highest C/N0 ratio after the frequency command offsets are added to the nominal carrier commands; declaring the micro-jump event resolved when the highest C/N0 ratio is greater than or equal to the upper threshold; computing corrections for clock error estimates after resolution of the micro-jump event; and sending the corrections for the clock error estimates to a GNSS/inertial Kalman filter.
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- 19. The non-transitory computer readable medium of claim 19, wherein the GNSS receiver and the INS are configured in an ultra-tightly-coupled (UTC) navigation and signal tracking loop.
Specification