本文關(guān)鍵詞：超高頻河流表面動力學(xué)參數(shù)雷達(dá)設(shè)計(jì)與實(shí)驗(yàn)　出處：《武漢大學(xué)》2014年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 布拉格散射 多普勒頻移 表面流 超高頻雷達(dá)

【摘要】：全面認(rèn)識和充分利用淡水資源,能夠?yàn)槲覈膰野踩徒?jīng)濟(jì)建設(shè)提供有力的保障。傳統(tǒng)的水文儀器采用接觸式測量,安裝和維護(hù)不便；而微波遙感技術(shù)容易受到降雨、云霧等惡劣天氣的影響。因此本文提出利用非接觸式超高頻河流表面動力學(xué)參數(shù)雷達(dá)(URSDR:UHF River Surface Dynamics parameters Radar)來彌補(bǔ)上述不足。 超高頻雷達(dá)利用水流對雷達(dá)電波的布拉格散射形成的多普勒頻移來探測河流表面流徑向速度。URSDR系統(tǒng)采用線性調(diào)頻連續(xù)波的工作體制,利用回波信號的頻率和相位信息來提取動力學(xué)參數(shù)。URSDR系統(tǒng)的工作頻率為340MHz,帶寬為15.36MHz,并且?guī)芷跒?.1032s,一個(gè)相干積累時(shí)間內(nèi)包含512幀�；谏鲜鰠�(shù),URSDR的距離分辨率為9.77m,速度分辨率達(dá)0.0084m/s。 URSDR系統(tǒng)由天線、發(fā)射機(jī)、接收機(jī)、計(jì)算機(jī)、線性電源組成。URSDR接收機(jī)是全數(shù)字雷達(dá)接收機(jī),通過數(shù)字端的FPGA產(chǎn)生本振和回波信號混頻,將射頻載頻直接搬移至零頻。和傳統(tǒng)的超外差雷達(dá)接收機(jī)相比,省去了模擬端的混頻器,因此簡化了系統(tǒng)結(jié)構(gòu),增加了動態(tài)范圍。URSDR發(fā)射機(jī)將線性調(diào)頻信號放大到所需的功率；天線采用“一發(fā)六收”的方法,發(fā)射和接收天線均為可替換的八木天線；計(jì)算機(jī)用于初始參數(shù)配置、數(shù)據(jù)存儲等；線性電源為系統(tǒng)提供高質(zhì)量的電源。 URSDR系統(tǒng)接收機(jī)由模擬板、頻綜板、數(shù)字板組成。模擬板中,設(shè)計(jì)合適的放大器、濾波器、開關(guān)電路等實(shí)現(xiàn)高靈敏度、大增益、寬動態(tài)范圍和高隔離度。頻綜板中,用80MHz高穩(wěn)定、低抖動的時(shí)鐘作為時(shí)鐘源；PLL (Phase Locked Loop)芯片產(chǎn)生983.04MHz的時(shí)鐘參考信號；DDS (Direct Digital Synthesis)芯片產(chǎn)生所需的線性調(diào)頻信號。FPGA將PLL和DDS的參數(shù)預(yù)先存放在RAM (Random Access Memory)中,然后以正確的時(shí)序?qū)懭氲叫酒型瓿膳渲�。�?shù)字板中,時(shí)鐘管理芯片將PLL輸出的81.92MHz信號分配給FPGA (Field Programmable Gate Array)作為系統(tǒng)時(shí)鐘,以及六個(gè)C (Analog-Digital Converter)作為采樣時(shí)鐘；ADC芯片具有寬模擬帶寬、高采樣率、高分辨率,適合對模擬板放大濾波后的回波信號進(jìn)行射頻帶通采樣；FPGA芯片對采樣數(shù)據(jù)進(jìn)行數(shù)字下變頻處理：CORDIC (COordinate Rotate Digital Computer)算法實(shí)現(xiàn)正交解調(diào)；CIC (Cascaded Integrator Comb)抽取濾波器實(shí)現(xiàn)大倍率抽取和濾波；DFT (Discrete Fourier Transform)模塊將處理后的時(shí)域信號變換到頻域。USB (Universal Serial Bus)芯片將數(shù)據(jù)高速的傳輸?shù)街鳈C(jī)端。主機(jī)端程序?qū)?shù)據(jù)進(jìn)行兩次快速傅里葉變換(FFT),提取目標(biāo)的距離和速度信息。 URSDR系統(tǒng)的閉環(huán)測試中,通過對-20dBm的射頻發(fā)射信號延時(shí)一定時(shí)間來模擬目標(biāo)的回波信號。接收機(jī)對回波信號進(jìn)行解調(diào)、抽取、濾波。經(jīng)過第一次FFT后得到距離譜,不同的頻偏對應(yīng)不同的距離元,并且相位穩(wěn)定性在0.080以內(nèi),幅度穩(wěn)定性在0.0025dB以內(nèi)。經(jīng)過第二次FFT后得到距離-多普勒譜,由于目標(biāo)沒有運(yùn)動,因此多普勒峰值應(yīng)該出現(xiàn)在零頻。 2013年3月,URSDR系統(tǒng)在武漢東湖完成了原理性實(shí)驗(yàn),成功驗(yàn)證了河流表面對電磁波散射作用的基本規(guī)律。2013年7月,URSDR系統(tǒng)在武漢長江完成了表面流速探測實(shí)驗(yàn)。然后建立河流回波譜模型,分析和比對了實(shí)測數(shù)據(jù)和仿真結(jié)果,討論雷達(dá)最大探測距離與流速的關(guān)系,并繪制徑向流圖,驗(yàn)證了系統(tǒng)的正確性。
[Abstract]:To fully understand and make full use of freshwater resources, can provide powerful guarantee for national security and economic construction in China. Hydrological instruments used in traditional contact measurement, installation and maintenance of inconvenience; and microwave remote sensing technology is easily affected by the rainfall, fog and other inclement weather effects. Therefore this paper proposes the use of non-contact ultra high frequency of river surface the kinetic parameters of radar (URSDR:UHF River Surface Dynamics parameters Radar) to compensate for these shortcomings.
Doppler frequency shift of UHF radar using water on the formation of Prague scattering of radar waves detection of the river surface using linear frequency modulation continuous wave system work flow.URSDR system to extract the frequency of radial velocity, kinetic parameters of.URSDR system for 340MHz using frequency and phase information of the echo signal, the bandwidth is 15.36MHz, and a frame period is 0.1032s. A coherent time contains 512 frames. Based on the above parameters, the distance of URSDR resolution is 9.77m, the speed of resolution up to 0.0084m/s.
The URSDR system consists of antenna, transmitter, receiver, computer, linear power supply.URSDR receiver is a digital radar receiver, the vibration and the echo signal by mixing FPGA digital terminal of the RF carrier will directly move to zero frequency. Compared with the traditional radar receiver superheterodyne mixer, eliminating the simulation terminal, thus simplifying the system the structure, increase the dynamic range of the.URSDR transmitter the chirp signal is amplified to the power required by the method of "one antenna; six receiving, transmitting and receiving antenna are Yagi antenna can be replaced; the computer used for the initial configuration, data storage; linear power supply high quality power for the system.
The URSDR receiver from the analog board, frequency synthesizer board, digital plate. Analog board, design appropriate amplifier, filter, switch circuit to realize high sensitivity, high gain, wide dynamic range and high isolation. The frequency synthesizer in 80MHz, with high stability, low jitter clock as clock source (PLL; Phase Locked Loop) 983.04MHz chip reference clock signal; DDS (Direct Digital Synthesis) chip to generate LFM signal required for.FPGA parameters of PLL and DDS in RAM (Random Access - Memory), and then to write to the chip in order to complete the configuration. The digital clock management board, chip the distribution of 81.92MHz output signal of PLL to FPGA (Field Programmable Gate Array) as the system clock, and six C (Analog-Digital Converter) as the sampling clock; the ADC chip has wide bandwidth, high sampling rate, high Resolution, suitable for analog board amplification echo signal filtered RF bandpass sampling; FPGA chip to process the sampling data of DDC treatment: CORDIC (COordinate Rotate Digital Computer) algorithm to realize quadrature demodulation; CIC (Cascaded Integrator Comb) decimation filter to realize rate decimation and filtering; DFT (Discrete Fourier Transform) module the time domain signal into frequency domain.USB (Universal Serial Bus) chip high-speed data transfer to the host. The host program of data for the two fast Fourier transform (FFT), distance and speed information extracted from the target.
URSDR closed-loop test system, to simulate the target echo signal through the radio frequency of -20dBm signal time delay. The receiver demodulates the echo signal extraction, filtering. After the first FFT after the distance spectrum, different frequency offset corresponding to different element distance and phase stability, amplitude stability in within 0.080. Less than 0.0025dB. After second FFT after range Doppler spectrum, because no movement, so Doppler peak should appear in the zero frequency.
In March 2013, URSDR completed the principle experiment in Wuhan East Lake and successfully verified the basic rules of.2013 river surface electromagnetic wave scattering effect of URSDR system in July, the Yangtze River in Wuhan completed the surface velocity detection. Then the establishment of river echo spectrum model, analysis of measured data and simulation results and comparison, discuss the relationship between radar detection the distance and velocity, and draw a radial flow diagram, verify the correctness of the system.

【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TN957.5

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