Goertzel Filter Radar Tracking Frequency Resolution
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Solution Overview
Problem
Radar systems face challenges in accurately determining the frequency of echo signals due to high sidelobes and frequency smearing caused by discrete Fast Fourier Transform (FFT) processing, which reduces their ability to track objects, and increasing FFT length requires additional hardware and longer computation times.
Innovation Solution
The method involves shifting the discrete frequency spectrum in frequency space, filtering it with a shifted filter, and determining the tracking parameter from the central frequency where the intensity is at a peak, allowing for improved frequency resolution without increasing hardware or computation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the length of the FFT is increased to improve frequency resolution, then the frequency resolution is improved, but additional hardware is required and computation time increases
Solution Approach 1:
The patent changes the parameter of frequency bin alignment by introducing a frequency shift amount that aligns the peak of the frequency spectrum with the center frequency of a frequency bin. This allows achieving better frequency resolution through parameter optimization rather than increasing FFT length, thereby avoiding additional hardware requirements
Solution Approach 2:
The patent performs preliminary frequency alignment by calculating an optimal frequency shift amount before determining the final frequency. This preliminary action of aligning the spectrum peak with the frequency bin center improves measurement precision without requiring increased computational resources or additional hardware
2Measurement precision
If the length of the FFT is increased to improve frequency resolution, then the frequency resolution is improved, but computation time increases
Solution Approach 1:
The patent optimizes the frequency measurement by changing parameters (frequency shift amount) rather than increasing the fundamental FFT length. This approach achieves improved frequency resolution through parameter tuning while maintaining the same computation time and processing resources
Solution Approach 2:
The patent applies a partial correction approach by introducing a frequency shift amount that aligns the spectrum peak with the frequency bin center, rather than performing a complete re-processing with longer FFT. This partial action achieves the desired frequency resolution improvement without the full computational cost of increasing FFT length
3Ease of operation
If standard FFT processing is used, then processing is simple, but high sidelobes and frequency smearing occur reducing tracking ability
Solution Approach 1:
The patent performs a preliminary frequency alignment step by calculating and applying a frequency shift amount before final frequency determination. This preliminary action reduces frequency smearing and improves peak detection accuracy while maintaining relatively simple processing through the use of Goertzel filter
Solution Approach 2:
The patent introduces an intermediary frequency shift amount calculation step that mediates between the raw FFT output and the final frequency determination. This intermediary step aligns the spectrum peak with the frequency bin center, reducing sidelobes and improving measurement precision without significantly complicating the overall processing
Data Source
AI summary
A radar system and method of determining a tracking parameter for a target in a radar system is disclosed. A transmitter transmits a source signal at a target and a receiver receives an echo signal from the target corresponding to the source signal. A processor provides a discrete frequency spectrum for the echo signal, shifts the discrete frequency spectrum in frequency space by a selected amount to obtain a shifted spectrum, filters the shifted spectrum using a filter that is shifted in frequency space a same amount as the shifted spectrum, and determines a tracking parameter of the target from a central frequency of the frequency space at which an intensity of the shifted and filtered spectrum is a peak intensity.