Collision Avoidance Radar Key Technologies

Collision avoidance radar, especially millimeter-wave collision avoidance radar, is a technique field that developing itself very fast at the present time. It has a comprehensive applied range. Along with increasing deterioration of operational circumstances,it becomes more and more important and difficult to solve the multi-object problems and restrain the noise interferences. Therefore, the non-linearity of LFM (linear Frequency Modulated), the multi-object problems, the noise interferences restraining and the spread spectrum technique are studied in this dissertation. Some new methods are presented, which could solve the multi-object problems and restrain the noise interferences in some degree, and could provide academic basic for developing the collision avoidance radar. The main contributions of this dissertation concentrate in a few aspects as follows. 1. The mathematical modeling of the collision avoidance radar is discussed. Collision avoidance radar pivotal techniques and its status in quo is discussed, the mathematical modeling of the collision avoidance radar has been achieved. The reality of high-linearity LFM signal, solving multi-object problems and restraining the noise interferences are its key techniques are pointed out. 2. A new method to produce high-linear, low-spurious and wide-band LFM radar wave signal is proposed. Based on analyzing that there are disadvantage to implement LFM signal by traditional methods, a new method based on triple tuned algorithm to achieve high-linear, low-spurious and wide-band LFM radar wave signal with DDS is obtained. Theoretical and experimental results show that the spurious level is below -70dBc and the phase-noise level is better than -100dBc/Hz@1kHz. A real-timely non-linearity emendating method in the echos of radar based on DDS is discussed. The reason is that the requirement of the radar LFM linearity is more and more high. 3. A modified transformable periods and symmetrical LFM radar wave signal is presented. The general collision avoidance radar wave signals, such as sawwooth wave signal, symmetrical triangle wave signal, multi-wave signal and multi-frequency signal, are discussed, and theirs shortcomings are pointed out. A new transformable periods and symmetrical LFM radar wave signal has been proposed to simultaneously improve measuring precision of distance and velocity of the object Based on the two-step stretch processing method, theoretic derivation shows that by using this method the multi-object problems may be solved in some degree. 4. A New Fractional Fourier Transform is presented. It is more difficult to estimate and separate LFM as a result of the appearance of multi-object and the applying of Multi-LFM radar wave signal. It couldn't detect validly the multi-object signal and retrain the noise interferences by using the classic Fourier transform. On the other hand, if using the time-ferequency distributing tools, it will be difficult to retrain...