| Orthogonal waveform phased array radar also named MIMO radar is the improved product of traditional phased array radar. The signals of elements for traditional phased array radar are highly interrelated and can be processed coherently. In orthogonal waveform MIMO radar, the elements on transmit are divided into a number of subarrays in pitch direction. The subarrays transmit mutual orthogonal waveforms, so the wide and low gain beam is formed on transmit. MIMO radar has many performance improvements, such as the better anti-interception performance, better velocity resolution, the advanced ability of low speed target detection under strong clutter, and the enhanced capability of weak target detection in clutter environment.In this dissertation, the MIMO radar signal characteristic and signal processing detecting problem are investigated, and the main research focus on the following issues: First, the principles and characteristics of MIMO radar are studied and analyzed. Besides, the performance improvements of MIMO radar over the traditional phased array radar counterpart are investigated.Second, the Orthogonal Frequency Division Multiplexing Linear Frequency Modulation signal (OFDM-LFM), Orthogonal Polyphased Code and Discrete Frequency Coding Waveform (DFCW) used in MIMO mode are analyzed. Among them the OFDM-LFM signal is especially studied, including the parameters setting problem investigated in detail and the conclusion also drawn that different parameters are needed to select due to different working modes. Further more, the processing architecture is analyzed. Utilizing the direction and range coupling effect of synthetical OFDM-LFM signal, a simplified signal processing architecture is proposed, the project complexity mitigated. In the end, the range resolution is analyzed by simulation, and range resolution of wide bandwidth effect can be gained when OFDM-LFM signal used in MIMO mode.Then, the moving target detecting (MTD) and constant false alarm rate (CFAR) detecting technologies are investigated. What's more, different kinds of CFAR methods under different clutter environments are discussed and compared. Also, the velocity resolution,low velocity target detection and the influence of AD quantification on detecton are studied in detail, also the simulation is done to demonstrate that MIMO is superior to traditional phased array radar in these aspects.Last, the simulation platform building is investigated, including signal generating, transmitting, processing and detecting. Especially the moving target detection MTD, the CFAR processing and detecting judgment modules are further researched. The main simulation results of MIMO radar are also given. |
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