GPS Receiver Cross-Correlation Interference Suppression
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Solution Overview
Problem
Conventional GPS receivers face challenges in quickly acquiring and accurately measuring weak GPS signals indoors and in urban environments due to cross-correlation interference from stronger signals, which existing methods struggle to effectively suppress without overcompensating or requiring high computational complexity.
Innovation Solution
A method involving a two-dimensional delay-Doppler accumulated power pattern is used, where partial averages of accumulated powers are calculated over specific code bins to subtract interference, preserving signal correlation shapes and enabling accurate Doppler frequency measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If strong signal compensation is deeply suppressed to remove interference, then cross-correlation interference is reduced, but the replica becomes stronger than the original signal causing overcompensation and tracking errors
Solution Approach 1:
The patent implements feedback by continuously monitoring the correlation peak strength and comparing it against expected signal characteristics. The system adjusts the compensation level dynamically based on feedback from the correlation processor, preventing overcompensation while maintaining interference suppression. This closed-loop approach ensures the replica subtraction does not exceed the actual interference level.
Solution Approach 2:
The patent applies partial action by selectively compensating only for the identified strong signal components rather than attempting complete suppression of all interference. The compensation is applied proportionally based on the measured signal strength and correlation results, avoiding the excessive action that would cause overcompensation and tracking errors.
2Device complexity
If conventional correlation processing is used to acquire weak GPS signals, then signal processing is simple, but weak signals cannot be detected in the presence of strong cross-correlation interference
Solution Approach 1:
The patent performs preliminary action by identifying and compensating for strong interfering signals before the main correlation processing of weak signals. The system first detects strong signals, generates their replicas, and subtracts them from the received signal, creating a cleaned input for subsequent weak signal acquisition. This preliminary interference removal enables conventional correlation processing to successfully detect weak signals that would otherwise be masked.
Solution Approach 2:
The patent extracts and removes the harmful strong signal components from the received signal before processing weak signals. By separating the strong interference from the weak signal environment and selectively subtracting only the identified interferers, the system maintains simple correlation processing while improving weak signal detection capability.
3Measurement precision
If signal search is performed to resolve time and frequency uncertainty, then signal acquisition is accurate, but it takes too much time for weak signal acquisition in difficult environments
Solution Approach 1:
The patent performs preliminary action by pre-processing the signal to remove strong interferers before the main signal search and acquisition process. This preliminary cleaning of the signal environment allows the correlation search to converge faster and with higher accuracy, reducing the time required to resolve time and frequency uncertainty for weak signals.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively counteracting the effect of strong interfering signals before they can mask or distort the weak signal parameters. By subtracting strong signal replicas in advance, the system prevents interference from corrupting the correlation measurements, enabling faster and more accurate signal parameter resolution.
Data Source
AI summary
A method for processing weak indoor signals in presence of cross-correlation or continuous wave interference and associated GPS receiver are provided. The method comprises providing a two-dimensional delay-Doppler accumulated power pattern having a plurality of accumulated powers corresponding to frequency bins and code bins; for a predetermined frequency bin, determining partial average value of accumulated powers over specific set of code bins so that the major part of signal energy is intentionally not included in the partial average; and subtracting the partial average value from all accumulated powers for the predetermined frequency bin; repeating the partial average calculation and subtraction for each frequency bin of a pattern to generate a two-dimensional delay-Doppler accumulated power pattern with suppressed interference effect.