Multi-Frequency GPS Receiver Ionospheric Delay Correction
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Solution Overview
Problem
Current GPS receivers use single frequency ionospheric models to correct for ionospheric delays, which are insufficient in accuracy, leading to position errors due to signal distortions primarily caused by the ionosphere.
Innovation Solution
A method and system that utilize multiple carrier frequencies (e.g., L1, L2, and L5) to determine ionospheric time delays by receiving and processing signals with antennas, amplifiers, analog-to-digital converters, correlators, and processors to calculate the time group delay coefficient, thereby improving positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single frequency ionospheric models are used to correct GPS signals, then the correction process is simple, but the position accuracy is insufficient due to signal distortions
Solution Approach 1:
The patent changes the frequency parameter by receiving and processing GPS signals at multiple carrier frequencies (L1, L2, L5) instead of a single frequency. This allows the system to determine ionospheric time delays at different frequencies and calculate the time group delay coefficient, thereby improving position accuracy while accounting for frequency-dependent ionospheric effects
Solution Approach 2:
The patent adds the frequency dimension to the signal processing by utilizing multiple carrier frequencies simultaneously. This dimensional expansion enables the correlator to measure time group delay differentials across different frequencies, providing additional information to correct ionospheric delays and improve positioning accuracy
2Measurement precision
If multiple carrier frequencies are used to determine ionospheric time delays, then position accuracy improves, but the system complexity increases
Solution Approach 1:
The patent implements multi-functionality by using the same receiver components (antenna, amplifier, ADC, correlator, processor) to handle multiple frequency signals simultaneously. The correlator correlates each frequency signal with the appropriate code to determine time group delay differentials, and the processor calculates the time group delay coefficient, allowing a single system to perform both single-frequency and multi-frequency ionospheric correction
Solution Approach 2:
The patent segments the signal processing into separate frequency channels, with each carrier frequency (L1, L2, L5) being amplified, converted, and correlated independently. This segmentation allows the system to measure ionospheric delays at each frequency separately and combine the information to improve overall position accuracy
3Measurement precision
If ionospheric delays are not corrected, then the receiver structure remains simple, but position errors occur due to signal distortions
Solution Approach 1:
The patent performs preliminary action by determining the time group delay coefficient in advance through multi-frequency signal processing. The processor calculates this coefficient by using the time group delay differential measured by the correlator, and this pre-calculated coefficient is then used to correct ionospheric delays in position calculations, improving accuracy before final position determination
Data Source
AI summary
The disclosed method for determining atmospheric time delays involves receiving at least two signals, where the signals each have a different carrier frequency. The method further involves amplifying each of the signals with a respective amplifier for each of the signals to produce amplified signals. Also, the method involves digitizing each of the amplified signals with a respective analog to digital converter (ADC) for each of the amplified signals to produce digital signals. In addition, the method involves correlating each of the digital signals with a code using a respective correlator for each of the digital signals to determine the time group delay differential between the signals. Further, the method involves calculating, with at least one processor, the time group delay coefficient of the signals by using the time group delay differential. The time group delay coefficient is used to correct for the atmospheric time delays in the signals.