Orthogonal Radar Signal Generation via Polyphase Code Optimization
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Solution Overview
Problem
Conventional radar systems face challenges in maintaining orthogonal performance between signals, especially when the number of radars increases, due to insufficient frequency resources and interference issues in frequency-sharing scenarios, particularly with frequency-modulation based systems.
Innovation Solution
A method and apparatus for generating orthogonal radar signals based on frequency modulation, which involves generating frequency-modulation waveforms, orthogonal code sets, and optimizing polyphase codes through an objective function that balances autocorrelation and cross-correlation peaks to minimize interference and maintain orthogonality across multiple radars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency modulation waveforms are used for radar transmission, then the radar can operate in frequency-sharing scenarios, but the orthogonal performance between signals decreases as the number of radars increases
Solution Approach 1:
The patent optimizes the parameters of polyphase codes (phase values, code lengths, and structures) to improve orthogonal performance. By adjusting these parameters, the system maintains low cross-correlation peaks even when multiple radars share the frequency band, thus resolving the degradation of orthogonal performance with increasing radar numbers
Solution Approach 2:
The patent combines frequency modulation waveforms with optimized polyphase codes to create composite radar signals. This composite approach integrates the advantages of both frequency modulation (good range resolution) and polyphase codes (improved orthogonality), enabling effective frequency sharing while maintaining signal orthogonality
2Measurement precision
If conventional frequency modulation radar signals are used, then the system can achieve good range detection performance, but the speed detection performance and orthogonal performance are poor
Solution Approach 1:
The patent creates composite radar signals by modulating frequency-modulated waveforms with optimized polyphase codes. This composite structure preserves the excellent range resolution of frequency modulation while adding the orthogonal properties and Doppler tolerance of polyphase codes, thereby improving both speed detection and orthogonal performance simultaneously
Solution Approach 2:
The patent divides the radar signal into distinct components: the frequency-modulated carrier waveform and the polyphase code sequence. This segmentation allows independent optimization of each component's properties, enabling the signal to achieve both good range detection (from the FM waveform) and improved speed detection with orthogonality (from the polyphase code)
3Reliability
If phase code diversity is used for frequency sharing, then the orthogonal performance is excellent, but the system complexity increases due to pulse division and code modulation
Solution Approach 1:
The patent pre-calculates and stores optimized polyphase code sets that are specifically designed for frequency-modulated waveforms. These pre-optimized codes can be directly applied without requiring complex real-time optimization, thus reducing the computational burden and system complexity while maintaining excellent orthogonal performance
4Productivity
If the number of concurrent radars is increased to improve spectrum efficiency, then the spectrum utilization improves, but the interference between radars increases and orthogonal performance decreases
Solution Approach 1:
The patent optimizes polyphase code parameters (phase values, code lengths, and structures) specifically for multi-radar frequency-sharing scenarios. These optimized parameters ensure that cross-correlation peaks remain low even when many radars operate concurrently, thereby enabling high spectrum efficiency while minimizing interference through maintained orthogonal performance
Data Source
AI summary
Disclosed is a method and apparatus for generating a radar signal, in which performance of radar detection is ensured while increasing a spectrum efficiency in a radar network. The method comprises generating a set of frequency-modulation waveforms, generating an orthogonal code set, generating a set of coded frequency-modulation waveforms through element operation between the set of frequency-modulation waveforms and the orthogonal code set, calculating an objective function for the set of frequency-modulation waveforms with regard to a different set of coded frequency-modulation waveforms and previous sets of coded frequency-modulation waveforms, and selecting a current polyphase code set as an optimized polyphase code set when a result of current calculation is better or smaller than a result of previous iteration, and performing phase perturbation by replacing an element randomly selected in the current polyphase code set selected as the optimized polyphase code set with another admissible-phase element.