Link-Path Delay Estimation Using Phase-Shifted Fine Timing
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Solution Overview
Problem
Conventional techniques for signal-path delay estimation lack sufficient resolution for systems of spatially-distributed sensors and radar-warning receiver systems, which is crucial for accurate signal-source location and synchronization.
Innovation Solution
A high-resolution link-path delay estimator is employed, which includes a phase-shifter to phase-shift a transmit signal by multiple phase-shift values, samples a loopback signal to generate a sampled signal output, and correlates it with a noise-reduced version to determine a fine-delay estimate, combining it with a coarse delay estimate to achieve precise signal-path delay measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional delay estimation techniques are used, then device complexity is reduced, but measurement precision deteriorates due to insufficient resolution for spatially-distributed sensor systems
Solution Approach 1:
The delay estimation process is segmented into two distinct stages: coarse delay estimation using conventional techniques to determine the integer number of symbol periods, and fine delay estimation using phase-shifting and correlation to determine the fractional portion within a symbol period. This segmentation allows each stage to use optimized methods for its specific resolution requirements, achieving high overall precision without excessive complexity.
Solution Approach 2:
The invention transitions from one-dimensional time-domain sampling to two-dimensional analysis by introducing phase-shifting across multiple dimensions. By varying the phase shift values and correlating across this expanded phase-time space, the system extracts fine delay information that cannot be obtained through conventional single-dimensional time-domain methods alone.
2Measurement precision
If high-resolution delay estimation is implemented, then signal-source location accuracy is improved, but loss of time increases due to multiple processing steps
Solution Approach 1:
The coarse delay estimate is obtained first as a preliminary action that provides the foundation for the fine delay estimation. This preliminary estimation establishes the integer symbol period component, allowing the subsequent fine estimation to focus only on determining the fractional portion within that symbol period, thereby reducing the overall processing burden.
Solution Approach 2:
The phase-shifting operation is performed periodically across a set of discrete phase-shift values (e.g., 0, 45, 90, 135 degrees). This periodic sampling of phase space allows the correlation process to efficiently identify the fine delay by finding the phase shift that maximizes correlation, completing the measurement in a systematic and time-efficient manner.
3Measurement precision
If phase-shifting with multiple values is used, then delay estimation precision is improved to within a fraction of a symbol period, but device complexity increases due to additional processing elements
Solution Approach 1:
The invention changes the phase parameter of the transmit signal across multiple discrete values (e.g., 0°, 45°, 90°, 135°) rather than maintaining a fixed phase. By systematically varying this single parameter and observing the correlation results at each phase shift value, the system extracts fine delay information without requiring complex hardware modifications, achieving high precision through parameter modulation.
Data Source
AI summary
Embodiments of a high-resolution link-path delay estimator and method are generally described herein. The high-resolution link-path delay estimator may estimate a signal-path delay of a signal path between a master and remote device. The high-resolution link-path delay estimator may phase-shift a transmit signal of alternating symbols by phase-shift values and may sample a loopback signal. A noise-reduced version of the sampled signal output may be correlated with a step function to generate a correlation value for each of the phase-shift values. One of the phase-shift values may be selected to generate a fine-delay estimate which may be added to a coarse delay estimate to determine the signal-path delay. The coarse delay estimate may be an estimate of the signal-path delay to a nearest symbol period of the transmit signal and the fine-delay estimate may be an estimate to within a fraction of the symbol period.