Radar Signal Processing for Doppler-Induced Ranging Errors
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Solution Overview
Problem
Conventional radar apparatuses face performance degradation due to increased side lobes and incorrect ranging when a target Doppler frequency is present, leading to poor detection performance.
Innovation Solution
A radar apparatus that converts reception signals into range-direction and hit-direction frequency domains, using a correlation unit to generate reference signals for pulse compression and integration, effectively separating signals by velocity and range to improve detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional radar apparatuses perform coherent integration of reception signals with different center frequencies assuming no target Doppler frequency, then ranging resolution is improved and side lobes are suppressed, but detection performance deteriorates when target Doppler frequency is present
Solution Approach 1:
The patent segments the reception signal processing into multiple velocity bin groups, where signals are separately processed for each velocity bin range. This segmentation allows the system to handle different Doppler frequency scenarios independently, preventing the degradation of detection performance while maintaining ranging resolution through targeted processing in each segment.
Solution Approach 2:
The patent changes the processing parameters dynamically based on the detected velocity bin distribution. When target Doppler frequency is present, the system adjusts the integration parameters and signal processing characteristics for each velocity bin group, allowing optimal performance across varying Doppler conditions while maintaining high ranging resolution.
2Device complexity
If conventional radar apparatuses integrate reception signals over a fixed range, then processing is simplified, but ranging accuracy deteriorates when target Doppler frequency causes pulse-compressed signal position deviation
Solution Approach 1:
The patent implements dynamic range adjustment by determining velocity bin groups based on detected Doppler characteristics and adaptively setting the integration range for each group. This dynamic approach compensates for pulse-compressed signal position deviation caused by target Doppler frequency, maintaining ranging accuracy without requiring overly complex fixed-processing systems.
Solution Approach 2:
The patent performs preliminary velocity estimation and velocity bin grouping before the main integration process. This preliminary action allows the system to pre-determine the appropriate integration range and processing parameters for each velocity bin group, preventing ranging accuracy deterioration while keeping the overall processing complexity manageable through staged processing.
3Adaptability or versatility
If conventional radar apparatuses use different transmission frequencies for each transmission radar, then frequency diversity is achieved, but coherent integration becomes impossible due to phase differences, deteriorating detection performance
Solution Approach 1:
The patent introduces velocity bin groups as an intermediary processing stage between signal reception and final integration. By routing signals from different transmission frequencies through separate velocity bin group processing channels with matched filtering, the system maintains frequency diversity while enabling coherent integration within each velocity bin group, thereby improving detection performance.
Solution Approach 2:
The patent segments the coherent integration process into separate velocity bin group processing channels, where each channel handles signals from specific transmission frequencies independently. This segmentation allows coherent integration to be performed within each segment while preserving the frequency diversity benefits across different transmission radars, resolving the contradiction between frequency diversity and coherent integration capability.
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
The solution enhances target detection performance by mitigating the effects of target Doppler frequency, reducing side lobes, and ensuring accurate ranging, even in the presence of Doppler effects.
Implementation Method 1
a plurality of transmission radars for transmitting signals having transmission frequencies varying at predetermined intervals and a reception radar for receiving signals reflected from a target
Implementation Method 2
on the assumption that there is no influence of a target Doppler frequency
Data Source
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AI summary
A range-direction frequency domain converting unit (231-1) converts reception video signals into signals in a range direction frequency. A hit-direction frequency domain converting unit (232-1) converts the signals in the range direction frequency into signals based on the velocity and the range direction frequency so that the target Doppler frequency belongs to the same velocity bin number independently of variations in frequencies of transmission signals. A correlation unit (233-1) generates signals based on the velocity separated for each of the transmission frequencies and a range after correlation. An integration unit (234-1) generates band-synthesized signals based on the velocity and a range after correlation. A candidate target detecting unit (241) detects candidate targets based on the signal intensity from the output signals of the integration unit (233-1). A target relative velocity/relative range/arrival angle calculating unit (242) calculates the relative velocity, the relative range, and the arrival angle of the candidate targets.