Electronic Scanning Radar Phase Extraction via CAPON Method
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Solution Overview
Problem
Conventional electronic scanning radar systems face challenges in accurately extracting phase information due to the hiding of weak reflected waves by strong waves and the complexity of hardware requirements for varying sampling frequency and number of sampling, which affects distance and azimuth accuracy.
Innovation Solution
The system employs a CAPON (Capon) method to compute phase information by cutting short time data into smaller segments, estimating the inverse correlation matrix, and using Recursive Least Squares for efficient computation, allowing for high-accuracy phase extraction and adjustable distance-azimuth resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If FFT method is used to extract phase information, then the processing is simple, but weak reflected wave signals are hidden by strong reflected wave signals and measurement precision deteriorates
Solution Approach 1:
The patent changes the processing method from FFT to CAPON method, which modifies the mathematical approach to spectral estimation. This parameter change in the signal processing algorithm allows for accurate extraction of phase information from weak reflected wave signals even in the presence of strong signals, resolving the contradiction between processing simplicity and measurement precision.
2Measurement precision
If sampling frequency and number of sampling are changed to prioritize distance accuracy or azimuth accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent uses CAPON method with variable window lengths to dynamically adjust the balance between distance and azimuth resolution. By changing the window parameter in the signal processing algorithm rather than modifying hardware sampling parameters, the system achieves adaptive resolution control without increasing circuit complexity.
3Measurement precision
If AD converter is prepared for each antenna element to receive data simultaneously, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent segments the reception process by using a single AD converter that sequentially processes signals from different antenna elements through time-division multiplexing. The switcher divides the reception time into segments for each antenna element, allowing accurate data acquisition without requiring multiple AD converters, thus reducing device complexity while maintaining measurement precision.
4Device complexity
If switcher is arranged between antenna elements and AD converter to divide time for data reception, then device complexity reduces, but loss of time occurs
Solution Approach 1:
The patent implements periodic switching between antenna elements in a systematic time-division manner. The switcher cycles through each antenna element in sequence, and the CAPON method processes the sequentially acquired data to reconstruct spatial information. This periodic action minimizes time loss by efficiently utilizing the switching cycle and processing multiple antenna signals within a compact time framework.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise detection of target distance and azimuth with improved separation of targets and reduced operational costs, enhancing the radar's ability to prioritize resolution based on the search object's position.
Implementation Method 1
a transmitted signal, which is obtained by executing frequency modulation on continuous wave
Implementation Method 2
the received signal S2 and the transmitted signal S1 are mixed, with each other as shown in FIG. 1, thereby generating a beat signal S3 which component is a frequency difference between the received signal and the transmitted signal
Data Source
AI summary
An electronic scanning radar apparatus has a cutting portion for cutting receiving data which is comprised of N numbers of data for each channel into two more short time data having M (<N) numbers of data in a time direction for each channel, an inverse matrix estimator for computing and estimating an inverse matrix of the time series correlation matrix from the short time data, and a phase information producing portion for computing CAPON phase information out of the estimated inverse matrix of the time series correlation matrix in order to detect a distance, an azimuth and a relative speed of a target on the basis of a computed CAPON phase information.