GNSS Receiver Quantization Thresholds for Anti-Jamming Detection
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Solution Overview
Problem
Conventional anti-jamming detection schemes in GNSS receivers face difficulties in achieving desired sample populations due to the varying signal-to-noise ratio (SNR) degradation caused by interference signals, particularly continuous wave (CW) interference, which complicates the detection of spread-spectrum signals.
Innovation Solution
The implementation of a flexible RF receiver with an analog-to-digital (A/D) converter using non-zero quantization threshold magnitudes to adjust gain and sample statistics, combined with automatic gain control (AGC) and phase rotation circuits, to enhance anti-jamming performance by optimizing sample populations and reducing interference effects.
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 are utilized, but it becomes difficult to achieve desired sample populations
Solution Approach 1:
The patent changes the quantization threshold parameter from the conventional zero-threshold approach to non-zero threshold magnitudes. By setting thresholds at ±0.5 times the quantization step size, the system selectively passes samples that fall outside these threshold regions, effectively filtering out samples dominated by interference while maintaining adequate sample populations for correlation processing.
2Reliability
If automatic gain control adjusts amplification to optimize signal levels, then signal quality improves, but interference signal effects vary with arbitrary power ratios
Solution Approach 1:
The patent converts the harmful effect of interference signals into a beneficial filtering mechanism. By using non-zero quantization thresholds, the system exploits the fact that interference-dominated samples tend to fall within the threshold region and are therefore discarded. This transforms the interference problem into a useful selection criterion for identifying valid signal samples.
3Productivity
If quantization threshold is set to zero, then all samples are processed, but samples dominated by interference are included reducing SNR
Solution Approach 1:
The patent applies local quality by treating different sample regions differently based on their characteristics. Samples falling within the non-zero threshold region are assumed to be interference-dominated and are discarded, while samples outside this region are retained for processing. This localized filtering approach improves overall signal quality by selectively processing only the most reliable samples.
Data Source
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AI summary
A satellite navigation device (110) including a flexible radio frequency (RF) receiver (200) is described. The receiver (200) receives a signal (114) that includes at least a first spread- spectrum signal (210) from a first satellite. The receiver (200) has a first channel that includes an analog-to-digital (AfD) converter (338) to sample and quantize the signal and an automatic gain control (AGC) (330) to adjust an amplification of the signal (114). The A/D converter (338) has a first non-zero quantization threshold magnitude and a second non-zero quantization threshold magnitude. The AGC (330) 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.