Satellite Navigation Receiver Gain and Threshold Control Under Jamming
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Solution Overview
Problem
Conventional anti-jamming detection schemes in GNSS receivers face difficulties in achieving desired sample populations due to interference signals, which degrade the signal-to-noise ratio and make it challenging to discern spread-spectrum signals, especially at maximum rates of change of interfering signals.
Innovation Solution
A satellite navigation device with a flexible RF receiver that employs an analog-to-digital converter with non-zero quantization threshold magnitudes and automatic gain control to adjust signal amplification, allowing for improved sample statistics and reduced interference effects by using look-up tables for mapping and phase rotation to distribute residual bias uniformly, thereby enhancing anti-jamming performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional 3-level quantization is used to detect spread-spectrum signals, then samples near crests and troughs of interfering signals can be utilized, but it is difficult to achieve desired sample populations and the spread-spectrum signal remains difficult to discern at maximum rates of change of interfering signals
Solution Approach 1:
The patent changes the quantization parameter from conventional 3-level quantization to multi-level quantization with multiple non-zero thresholds. This allows the system to capture more statistical information about the received signal while maintaining robustness against interference. The multiple thresholds create multiple quantization levels that better represent the signal distribution, improving detection precision without excessive complexity increase.
Solution Approach 2:
The patent introduces dynamic threshold selection based on signal conditions. The AGC dynamically adjusts the quantization thresholds according to the received signal strength and interference conditions, allowing the quantization scheme to adapt to varying signal environments. This dynamic approach enables the system to maintain optimal detection performance across different interference scenarios.
2Reliability
If AGC adjusts gain based on first non-zero quantization threshold to produce predetermined probability of non-zero samples, then sample statistics are improved, but the system must handle arbitrary ratios of interference signal power to receiver noise power
Solution Approach 1:
The patent implements feedback through the AGC loop that continuously monitors the quantized signal statistics and adjusts the gain accordingly. The AGC uses the first non-zero quantization threshold to determine when to adjust gain, creating a feedback mechanism that maintains predetermined probability of non-zero samples. This feedback loop enables the system to automatically adapt to varying interference conditions and maintain reliable detection performance.
Solution Approach 2:
The patent changes the gain parameter dynamically based on the quantization threshold comparisons. By adjusting the gain to maintain a predetermined probability of non-zero samples, the system adapts to arbitrary interference-to-noise power ratios. This parameter adjustment strategy ensures reliable anti-jamming performance across diverse interference scenarios.
3Measurement precision
If look-up tables with multiple mappings are used for quantization, then sample population distribution is optimized, but device complexity increases
Solution Approach 1:
The patent pre-computes and stores quantization mappings in look-up tables during system design or initialization. The multiple mappings that optimize sample population distribution are calculated in advance and stored, avoiding the need for complex real-time computations during signal processing. This preliminary action reduces online computational complexity while maintaining optimized sample distribution.
Solution Approach 2:
The patent uses look-up tables to store pre-computed quantization mappings, effectively creating a copy of the complex transformation logic in a simplified tabular format. Instead of performing complex calculations during signal processing, the system retrieves pre-computed values from the look-up tables, reducing real-time computational complexity while maintaining measurement precision.
Data Source
AI summary
A satellite navigation device including a flexible radio frequency (RF) receiver is described. The receiver receives a signal that includes at least a first spread-spectrum signal from a first satellite. The receiver has a first channel that includes an analog-to-digital (A/D) converter to sample and quantize the signal and an automatic gain control (AGC) to adjust an amplification of the signal. The A/D converter has a first non-zero quantization threshold magnitude and a second non-zero quantization threshold magnitude. The AGC may adjust a gain in accordance with the first non-zero quantization threshold magnitude. The gain may correspond to a first pre-determined probability of a non-zero sample and the second non-zero quantization threshold magnitude may correspond to a second pre-determined probability of a non-zero sample.