Passive Radar Signal Processing for SNR and Range Extension
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Solution Overview
Problem
Conventional passive radar systems face challenges in extending detection range due to low signal-to-noise ratio (SNR) and increased processing load, particularly when trying to detect targets over a longer integration time or using methods like stretch processing.
Innovation Solution
A passive radar device that divides received signals into pulses and blocks for cross-correlation and Fourier transform processing, allowing for pulse-by-pulse range compression and block-by-block Doppler processing, with range migration compensation, to improve SNR and extend detection range without significantly increasing calculation load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integration time is extended to improve SNR and detection range, then the SNR improves, but the target moves between range cells causing range migration and Doppler frequency changes
Solution Approach 1:
The patent applies stretch processing to the direct wave signal to generate a reference signal that incorporates range migration corresponding to target speed in advance. This preliminary action allows the system to compensate for target movement during long integration periods without requiring the target to remain stationary in a single range cell
Solution Approach 2:
The patent divides the received signal into multiple pulses and processes them in units of blocks, where each block contains multiple pulses. This segmentation enables the system to handle range migration by processing smaller time intervals separately while maintaining overall long integration time for SNR improvement
2Length of stationary object
If stretch processing is applied to generate a reference signal with incorporated range migration, then the detection range can be extended, but the calculation amount increases causing heavier processing load
Solution Approach 1:
The patent divides the signal processing into pulse-by-pulse range compression and block-by-block Doppler processing. By segmenting the processing into smaller units and performing operations in a systematic sequence, the calculation complexity is managed more efficiently
Solution Approach 2:
The patent dynamically adjusts the processing approach by first performing pulse-by-pulse range compression, then block-by-block Doppler processing, and finally range migration compensation. This dynamic processing sequence optimizes computational efficiency while achieving the desired detection range extension
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 longer observing and integration times while maintaining a low calculation load, effectively enhancing the SNR and expanding the detection range of the passive radar system.
Implementation Method 1
an antenna for direct-wave reception for receiving a direct wave that directly arrives after being transmitted from a radio source
Implementation Method 2
an antenna for scattered-wave reception for receiving a scattered wave transmitted from the radio source and scattered by a target
Implementation Method 3
a pulse-by-pulse range compression unit for executing cross-correlation processing between the received signal of the direct wave and the received signal of the scattered wave on each of the divided pulses and calculating a pulse-by-pulse range profile
Implementation Method 4
a block-by-block Doppler processing unit for calculating a second Doppler frequency spectrum by executing block-direction Fourier transform
Implementation Method 5
executing pulse-direction Fourier transform in units of blocks
Data Source
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AI summary
Provided is a passive radar device capable of extending an observing time for a target and an integration time of a signal with a small calculation amount, sufficiently improving an SNR, and stretching a detection range. The passive radar device includes: a pulse-by-pulse range compression unit for executing cross-correlation processing between a received signal of a direct wave and a received signal of a scattered wave on each of pulses divided by a direct-wave reception unit and a scattered-wave reception unit and calculating a pulse-by-pulse range profile; a block-by-block Doppler processing unit for calculating a first Doppler frequency spectrum by executing pulse-direction Fourier transform in units of blocks each of which groups a plurality of pulses; a Doppler frequency cell-associated range migration compensation unit for compensating a range-direction movement amount with respect to the first Doppler frequency spectrum on a Doppler-frequency-cell-by-Doppler-frequency-cell basis and on a block-by-block basis; and a block-direction Doppler processing unit for calculating a second Doppler frequency spectrum by executing block-direction Fourier transform on an output from the Doppler frequency cell-associated range migration compensation unit.