應用於多重動態物體判讀之都卜勒雷達設計

本文分別設計一組單波束及一組水平四波束都卜勒雷達系統，並將其應用於多重動態物體之量測，並提出一後端判讀演算法以分辨不同運動速度之動態目標物。此兩套雷達系統採用直接降頻之連續波雷達架構:利用一高輸出功率之壓控震盪器產生訊號，並藉由功率分配器將訊號分別做為系統發射訊號及接收機之正交解調器的本地震盪端驅動源。接著接收由環境中反射之訊號並經過帶通濾波器濾除及低雜訊放大器放大後，由正交解調器將之與本地端訊號混頻後降至基頻。經數據擷取卡將訊號取樣後儲存至電腦，並利用NI LabVIEW平台進行後端先關數據呈現及進一步的數位訊號處理。而水平四波束系統之接收機藉由整合一切換波束式相位陣列天線系統，使系統額外具有空間掃描及定位的能力。為驗證系統及後端演算法的可行性，以掛載金屬板之線性馬達做為動態目標進行量測，藉由解調由正交解調器所輸出之I及Q訊號，可以得到動態物體運動所導致之都卜勒頻率飄移訊號。當動態目標為兩部以上以不同頻率擺動的線性馬達時，系統接收訊號中含有兩個以上動態物體之運動資訊時，藉由將訊號經短時間傅立葉轉換所得之時間頻譜圖以強度做為判別依據，依序將訊號中的最高強度成分濾除之疊代運算，不同擺動頻率之訊號成分將被一一解析出來。

關鍵字

雷達系統；都卜勒頻率飄移；短時間傅立葉轉換；時間頻譜圖

並列摘要

In this thesis, a single beam and a 4-beam Doppler radar systems are designed for dynamic motion detection on multiple targets. Along with the hardware, a new algorithm is proposed to distinguish moving targets with different motion velocities. These two continuous wave (CW) radar systems based on direct down-conversion receiver architecture are designed at 2.4 GHz. The RF signal generated from a voltage-controlled oscillator (VCO) is radiated from the antenna, while partial power is fed to the I/Q down-mixer serving as the local signal. The signal reflected from moving targets cause the Doppler shift. The received signal is then filtered and amplified by a band-pass filter (BPF) and a low-noise amplifier (LNA), and down-converted. Finally, the 4-way baseband signal is sampled and digitized through a data acquisition (DAQ) card. The sampled data are delivered to the computer and further processed on the NI LabVIEW platform. Furthermore, by integrating a phased-array system into the receiver, the 4-beam radar system possesses the ability of scanning and positioning in the space. To validate the system functionality, the primary testing is conducted with metal plates driven by linear motors, in which the motors are set to move forward and backward with fixed displacement. The Doppler frequency shift resulted from moving targets can be extracted from a I/Q demodulator. For the case of two motors with different motions, the received signal contains mixed motions, the system is still able to distinguish different motion component using iterative computation algorithm based on spectrum strength from STFT convolution.

並列關鍵字

Radar System ； Doppler Frequency Shift ； STFT

參考文獻

[1]L. P. Gotz and J. D. Albright, “Airborne Pulse Doppler Radar, ” IRE Transactions on Military Electronics, 1961 , pp.116-126.

[2]Jing Peng, Yaofei Ma, Guanghong Gong and Lian Han, "Real-time Detection Performance of Airborne Pulse Doppler Radar, ” ICIECS 2009. International Conference on, 2009 , pp.1-4.

[3]Gao Zhonghui, Shi Lin and Sun Jiyuan, “A new generation of fully coherent pulsed doppler weather radar,” CIE International Conference of Radar, Oct 8-10, 1996, pp.566-572.

[4]G. Viswanathan, R.C. Bhatia, V.P. Kamble and S.R. Rao,“Indian Doppler Weather Radar System-An Overview,” IGARSS '97. Remote Sensing - A Scientific Vision for Sustainable Development., 1997 IEEE International (Volume:3 ), Aug 3-8, 1997 , pp. 1129 -1131.

[5]Lixia Liu, Chongdi Duan, Hing Cheung So, Axin Jin and Xiaoning Wang, “An Investigation of Geostationary Doppler Weather Radar Performance Based on Mean Doppler Radial Velocity and Spectrum width Measurements” in IEEE International Geoscience and Remote Sensing Symposium (IGARSS), July 13-18, 2014 , pp.701 -713.

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應用於多重動態物體判讀之都卜勒雷達設計

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