Method of reducing inter-channel biases in GLONASS GNSS receivers
AssigneeTopcon Positioning Systems, Inc.
InventorsVladimir Victorovich Veitsel, Andrey Vladimirovich Veitsel, Konstantin Vladimirovich Chereshnev
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Abstract
The present invention discloses methods of accuracy improving for code measurements in GLONASS GNSS receivers. One component of error budget in code measurements of GLONASS receivers is caused by a difference in signal delays arising in the receiver analog Front End and antenna filter on different channel frequencies specific to GLONASS satellites. Methods to compensate for differences in delays for different GLONASS channel frequencies have been proposed using data collected from a GLONASS signals simulator.
Claims12
A method of reducing inter-channel bias in a GLONASS receiver, the method comprising:
- forming primary code measurements in the GLONASS receiver that includes an Analog Front-End and a multiple digital channels, each channel including a Delay Locked Loop (DLL), the Analog Front-End receiving different GLONASS signals at different frequencies from different GLONASS satellites;
- wherein each DLL includes a code sequence generator, a strobe generator, a correlator, a discriminator, and a loop filter, connected in a feedback loop,
- wherein the strobe generator forms a strobe sequence of strobes, one strobe for every PRN code chip received from a GLONASS satellite by the Analog Front-End and the DLL, with a position of each strobe center coinciding with a boundary of each PRN code chip, and a sign (+ or −) of each strobe corresponds to a sign (+ or −) of a next PRN code chip,
- wherein each strobe from the strobe generator has a number of opposite sign elements (both +1 and −1) such that a number of positive elements (+1's) is different from a number of negative elements (−1's), and a sign of the strobe is a sum of signs of all the elements;
- each channel calculating the primary code measurements based on an output of its DLL;
- and
- generating current coordinates based on the calculated primary code measurements.
A GLONASS receiver with reduced inter-channel bias, comprising:
- an antenna receiving signals from GLONASS satellites, the signals including PRN code chips;
- an Analog Front-End receiving and processing the signals received by the antenna, the Analog Front-End including a filter receiving that provides the filtered signals to a digital processing module that includes multiple channels, each channel including a DLL and a measurements generator;
- the measurements generator producing primary code measurements based on an output of its DLL;
- and
- a processor for calculating current coordinates based on the primary code measurements,
- wherein each DLL includes a code sequence generator, a strobe generator, a correlator, a discriminator, and a loop filter, connected in a feedback loop,
- wherein the strobe generator forms a strobe sequence of strobes, one strobe for every PRN code chip received from a GLONASS satellite by the Analog Front-End and the DLL, with a position of each strobe center coinciding with a boundary of each PRN code chip, and a sign (+ or −) of each strobe corresponds to a sign (+ or −) of a next PRN code chip,
- wherein each strobe from the strobe generator has a number of opposite sign elements (both +1 and −1) such that a number of positive elements (+1's) is different from a number of negative elements (−1's), and a sign of the strobe is a sum of signs of all the elements.
Dependencies are inferred from the claim text.