Microwave Photonics Radar With Flexible Multiplication and Coherent Reception
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Solution Overview
Problem
Current radar technologies face limitations in flexible frequency multiplication, complex photoelectric control links, and difficulty in coherent reception of broadband radar echo signals due to parasitic interference and amplitude/phase nonlinear effects.
Innovation Solution
A microwave photonics radar system utilizing optical injection locking and coherent receiving, employing distributed feedback lasers to filter and amplify high-order sidebands, enabling flexible frequency multiplication and real-time orthogonal de-chirping of broadband echo signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If optical frequency multiplication based on a special modulator is used, then frequency multiplication is achieved, but the frequency multiplication factor is limited and cannot be flexibly adjusted
Solution Approach 1:
The patent changes the working parameters of the distributed feedback laser (injection current, temperature) to tune its output frequency, enabling flexible adjustment of the frequency multiplication factor without changing the hardware structure. This resolves the contradiction by making the system adaptable while maintaining simple hardware architecture.
2Power
If strong non-ideal sideband beat frequency is present, then frequency multiplication occurs, but parasitic interference signals are generated
Solution Approach 1:
The patent extracts and eliminates the harmful sideband components through optical filtering in the distributed feedback laser cavity, keeping only the desired frequency multiplication components. This separates the useful signal from the parasitic interference, resolving the contradiction between signal strength and interference suppression.
3Adaptability or versatility
If traditional radar signal generation is used, then signal processing is simple, but broadband target echo signals cannot be received through coherent receiving
Solution Approach 1:
The patent makes the optical carrier frequency adjustable to match different echo signal frequencies, enabling the same coherent receiving system to handle multiple broadband signal scenarios. This universal design allows the system to be adaptable to different applications while maintaining a unified hardware platform.
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 system generates broadband radar signals with adjustable frequency multiplication factors, ensures high linearity and signal-to-noise ratio, and effectively suppresses interference, allowing real-time coherent reception of broadband echo signals.
Implementation Method 1
based on the optical injection locking mechanism, a distributed feedback laser is used to filter and amplify the high-order swept sidebands
Implementation Method 2
a broadband radar transmission signal with flexible and adjustable frequency multiplication factor is obtained
Implementation Method 3
Modulating an optical carrier fC, output by a master laser through an electro-optic modulator by using a baseband linear frequency modulation (LFM) signal
Implementation Method 4
one path being subjected to photoelectric conversion to obtain a frequency multiplication radar transmitting signal
Implementation Method 5
the other path of the radar detection optical signals serving as a reference optical signal to achieve coherent receiving of the radar echo signal together with the radar receiving optical signal
Data Source
AI summary
Discloses a coherent microwave photonics radar detection method and system based on injection locking frequency multiplication. The method uses a baseband signal to modulate an optical carrier to generate a modulated optical signal including a plurality of high-order sidebands; the modulated optical signal is divided into two paths which are respectively injected into two slave lasers for high-order sideband injection locking to obtain two locked sideband optical signals; Based on combining and splitting two locked sideband optical signals, the radar transmitting signal and receiving optical signal can be obtained through photo-detection and electro-optic modulation. After coherent detection of receiving optical signal, obtaining the intermediate frequency signal, and detection target information can be extracted from intermediate frequency signal by radar algorithm.