GLONASS Receiver Inter-Channel Bias Compensation
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Solution Overview
Problem
GLONASS positioning accuracy is compromised by differences in signal delays due to non-linearity of the receiver's phase-frequency characteristic, leading to biases that affect positioning accuracy, especially when receiving signals on different channel frequencies.
Innovation Solution
Three methods are proposed to reduce these errors: compensating for temperature-instable code biases, adjusting the operating point of the DLL discriminator characteristic, and using high-precision GLONASS signals, with a GLONASS simulator to account for delays in the receiver's analog component and external antennas, simplifying receiver designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common analog component is used to receive signals from all GLONASS satellites, then device complexity is reduced, but measurement precision deteriorates due to non-linearity of phase-frequency characteristic causing different delays for different channel frequencies
Solution Approach 1:
The patent applies preliminary action by measuring and storing bias values for different channel frequencies in advance. The system performs calibration measurements to determine the specific delay biases for each channel, stores these values in a lookup table, and then applies them during normal operation to correct the code measurements, thereby resolving the non-linearity issue without adding complex real-time correction hardware.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual code measurements and comparing them against the stored bias values for each channel frequency. The system uses the measured biases to generate correction values that are fed back into the positioning calculations, iteratively improving the measurement precision while maintaining the simple common analog component architecture.
2Adaptability or versatility
If frequency division multiply access is used in GLONASS, then adaptability is improved by allowing individual satellite frequencies, but measurement precision deteriorates due to non-linear phase-frequency characteristic causing inter-channel biases
Solution Approach 1:
The patent applies local quality by treating each channel frequency differently in terms of bias compensation. Instead of using a uniform correction approach, the system determines and applies channel-specific bias values tailored to each individual frequency's non-linearity characteristics. This allows the system to maintain the flexible frequency allocation of GLONASS while correcting the measurement precision issues specific to each channel.
3Productivity
If code measurements are taken for all GLONASS satellites, then productivity is improved by enabling navigation task solving, but measurement precision deteriorates due to differential delays affecting positioning accuracy
Solution Approach 1:
The patent performs preliminary calibration measurements for all channel frequencies to establish bias values before actual navigation processing. This pre-computed correction data is then applied during navigation operations to maintain both high productivity in processing multiple satellite signals and high measurement precision by removing differential delay effects.
Data Source
AI summary
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.