本文選題：精準(zhǔn)農(nóng)業(yè) + 軟件無線電�。� 參考：《北京郵電大學(xué)》2015年碩士論文

【摘要】：如何在有限的農(nóng)業(yè)資源基礎(chǔ)上,提高農(nóng)業(yè)的生產(chǎn)效率、經(jīng)濟(jì)效益與環(huán)境效益已經(jīng)成為我國農(nóng)業(yè)精細(xì)化進(jìn)程所必須要解決的問題。依托先進(jìn)的信息技術(shù)成為實(shí)現(xiàn)這一目標(biāo)的重要手段。在眾多的信息化技術(shù)中無線傳感器網(wǎng)絡(luò)技術(shù)無疑是農(nóng)業(yè)現(xiàn)代化研究最熱門的方向之一。 無線傳感器網(wǎng)絡(luò)技術(shù)包括了傳感器技術(shù)、微機(jī)電系統(tǒng)技術(shù)、無線通信技術(shù)、嵌入式計(jì)算技術(shù)和分布式信息處理技術(shù),它們具有功耗低的特點(diǎn)。也正是由于低功耗使得節(jié)點(diǎn)間的收發(fā)不像傳統(tǒng)的無線通信一樣可以覆蓋較大的范圍,當(dāng)應(yīng)用環(huán)境不一樣時(shí),無線傳感器網(wǎng)絡(luò)的覆蓋特性會有很大的不同。 農(nóng)業(yè)環(huán)境具有地勢多樣、天氣狀況復(fù)雜、面積龐大、農(nóng)作物生長周期長等特點(diǎn),這些特點(diǎn)給無線傳感器網(wǎng)絡(luò)技術(shù)的應(yīng)用帶來了挑戰(zhàn)。在實(shí)際環(huán)境下部署無線傳感器網(wǎng)絡(luò)前需要對信號的傳播環(huán)境有細(xì)致的了解，，才能保證網(wǎng)絡(luò)的覆蓋性。基于這點(diǎn),本文從兩個(gè)角度來分析測量農(nóng)田環(huán)境下信號的傳播特性。第一,我們使用無線傳感器節(jié)點(diǎn)和頻譜儀測量冬小麥在三種典型的生長期下433MHz信號的路徑損耗變化特性,整個(gè)測量工作在國家精準(zhǔn)化農(nóng)業(yè)基地完成,完成測量工作之后,利用matlab對所得數(shù)據(jù)進(jìn)行曲線擬合和回歸分析,得出農(nóng)業(yè)環(huán)境下433MHz信號的大尺度傳播模型,然后將所得模型與我們在室內(nèi)和室外空曠環(huán)境測量總結(jié)的模型進(jìn)行比較,分析麥田環(huán)境對信號傳播特征的影響；第二,使用軟件無線電平臺GNU Radio和USRP設(shè)計(jì)多徑時(shí)延特性測量系統(tǒng),系統(tǒng)由兩臺USRP組成,發(fā)送端發(fā)送M序列,接收端利用相同的M序列對接收信號進(jìn)行滑動(dòng)相關(guān)處理,提取相關(guān)后信號的功率延遲分布,通過功率延遲分布得到信號的多徑時(shí)延和多徑強(qiáng)度。在完成系統(tǒng)設(shè)計(jì)后,在北京郵電大學(xué)校園內(nèi)進(jìn)行了室外LOS和NLOS測試,得到兩種信道條件下433MHz無線信號的功率延遲分布,利用功率延遲分布得到該環(huán)境下信號的多徑傳播特性,驗(yàn)證了測量系統(tǒng)的有效性。
[Abstract]:How to improve agricultural production efficiency, economic benefit and environmental benefit on the basis of limited agricultural resources has become a problem that must be solved in the process of agricultural refinement in China.Relying on advanced information technology has become an important means to achieve this goal.Wireless sensor network (WSN) is one of the hottest research directions in agricultural modernization.Wireless sensor network technology includes sensor technology, MEMS technology, wireless communication technology, embedded computing technology and distributed information processing technology, which have the characteristics of low power consumption.Because of the low power consumption, the transceiver between nodes can not cover a large range like traditional wireless communication. When the application environment is different, the coverage characteristics of wireless sensor networks will be very different.The agricultural environment has the characteristics of diverse terrain, complex weather conditions, huge area and long crop growth cycle. These characteristics have brought challenges to the application of wireless sensor network (WSN) technology.In order to ensure the coverage of wireless sensor networks, it is necessary to have a detailed understanding of the signal propagation environment before deploying wireless sensor networks in the actual environment.Based on this, this paper analyzes the signal propagation characteristics in the field environment from two angles.First, we use wireless sensor nodes and spectrometers to measure the path loss characteristics of winter wheat 433MHz signals during three typical growth periods. The whole measurement was completed at the National Precision Agriculture Base.By using matlab curve fitting and regression analysis, the large scale propagation model of 433MHz signal in agricultural environment was obtained, and then the model was compared with the model that we summarized in indoor and outdoor open environment.The effects of wheat field environment on the signal propagation characteristics are analyzed. Secondly, a multi-path delay measurement system is designed using the software radio platforms GNU Radio and USRP. The system is composed of two USRP, and the transmitter transmits M sequence.The receiver uses the same M sequence to carry on the sliding correlation processing to the received signal, extracts the power delay distribution of the correlated signal, and obtains the multipath delay and the multipath intensity of the signal by the power delay distribution.After completing the system design, outdoor LOS and NLOS tests were carried out on the campus of Beijing University of posts and Telecommunications. The power delay distribution of 433MHz wireless signals was obtained under two channel conditions. The multipath propagation characteristics of the signals in this environment were obtained by using the power delay distribution.The validity of the measurement system is verified.
【學(xué)位授予單位】：北京郵電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S126;TN92

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