Link-Path Delay Estimation Using Coarse-Fine Symbol Timing
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Solution Overview
Problem
Conventional techniques for signal-path delay estimation in systems of spatially-distributed sensors and radar-warning receiver (RWR) systems lack sufficient resolution, making it difficult to accurately compensate for delays in signal paths, especially in applications requiring precise timing and synchronization.
Innovation Solution
A method involving a link-path delay estimator that uses a transmit signal with alternating symbols, phase-shifts, and loopback signals to generate both coarse and fine delay estimates, combining these to achieve high-resolution signal-path delay estimation by correlating noise-reduced sampled signals with a step function, allowing for precise compensation of signal delays in both fixed and wireless communication links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional delay estimation techniques are used, then the system is simpler to implement, but the measurement precision is insufficient for spatially-distributed sensor systems
Solution Approach 1:
The delay estimation process is segmented into two independent stages: coarse delay estimation using cross-correlation of signal waveforms, and fine delay estimation using phase-shifted signal sampling. This segmentation allows each stage to operate with optimized parameters, achieving high overall precision while maintaining manageable complexity through modular processing.
Solution Approach 2:
The patent transitions from single-dimension delay estimation to two-dimension estimation by introducing phase-shifted sampling in addition to time-domain correlation. This dimensional expansion enables fine-grained delay resolution within the coarse estimate range, significantly improving measurement precision without requiring a complete system redesign.
2Measurement precision
If higher resolution delay estimation is implemented, then synchronization accuracy improves, but the processing time increases
Solution Approach 1:
The coarse delay estimation is performed as a preliminary action to establish a rough delay value before the more computationally intensive fine delay estimation. This preliminary coarse estimate narrows the search space for fine estimation, reducing the processing time required while maintaining high precision through the subsequent fine-tuning stage.
Solution Approach 2:
By segmenting the estimation process into coarse and fine stages, the patent performs simpler, faster coarse estimation first, then applies more complex fine estimation only within a reduced range. This segmentation strategy achieves high precision while minimizing total processing time compared to a single-stage high-precision approach.
3Reliability
If conventional delay estimation is used, then the device complexity is lower, but the reliability of synchronization fails
Solution Approach 1:
The patent merges the outputs of coarse and fine delay estimators to produce a combined high-precision delay estimate. This merging of estimation results ensures reliable synchronization by leveraging the strengths of both simple cross-correlation and phase-shifted sampling, achieving robust performance that conventional single-stage methods cannot provide.
Solution Approach 2:
The segmentation into coarse and fine estimation stages ensures reliability by providing multiple levels of verification and refinement. The coarse estimate provides a baseline, while the fine estimate validates and refines the result, creating a redundant verification mechanism that improves synchronization reliability without requiring an entirely complex system.
Data Source
AI summary
A link-path delay estimator estimates a signal-path delay of a signal path between a master device and a remote device, by combining coarse delay estimates and a fine delay estimate. The coarse delay estimates indicate only an integral portion of the signal-path delay, selected as an integral multiple of a symbol period. The fine delay estimate indicates only a fractional portion of the signal-path delay, selected from a range of values that extends over one symbol period. The link-path delay estimator can combine the coarse and fine delay estimates using a first rule if the two most recent coarse delay estimates are equal, and a second rule if the two most recent coarse delay estimates differ. The coarse delay estimates can arise from both rising edges and falling edges of periodic signals sent along the signal path.