本文選題：半航空 + 瞬變電磁法��； 參考：《成都理工大學(xué)》2015年碩士論文

【摘要】：隨著人類對礦產(chǎn)資源的需求迅速增加,有限的礦產(chǎn)資源與人類不斷增長的需求之間的矛盾日益突出,使找礦工作重點逐漸轉(zhuǎn)變?yōu)樵陔[伏區(qū)、礦區(qū)深部及礦區(qū)外圍尋找隱伏礦和盲礦。半航空瞬變電磁法是近年來電法勘探領(lǐng)域發(fā)展較快的一種重要方法。瞬變電磁法是利用不接地回線或接地電偶源向地下發(fā)送一次場,在一次場的間歇期間利用回線或電偶極觀測二次渦流場的方法。瞬變電磁勘探方法中“渦流”從產(chǎn)生到結(jié)束的時間十分短暫,對取樣時間要求十分精確。要做到這點就必須使發(fā)射電流關(guān)斷后,在精確的某一時刻開始測量,從而接收系統(tǒng)與發(fā)射系統(tǒng)就必須實現(xiàn)精確的同步。本文立足于國土資源部公益性行業(yè)科研項目“基于無人機的半航空瞬變電磁勘查技術(shù)研究”,主要對其數(shù)據(jù)采集系統(tǒng)中的地面發(fā)射系統(tǒng),地面接收系統(tǒng)及無人機接收系統(tǒng)三者之間的采樣信號同步技術(shù)進行了研究。本文主要研究了三種同步技術(shù),振蕩器同步技術(shù)、無線同步技術(shù)、GPS同步技術(shù)的原理及實現(xiàn),并用GPS同步技術(shù)在半航空電磁測量系統(tǒng)中進行了實驗,同時對系統(tǒng)的抗干擾措施進行了研究并進行了應(yīng)用。振蕩器同步技術(shù)用了時鐘芯片PCF8563的可編程時鐘輸出,報警器及定時器功能,設(shè)置TI/TP=1,此時中斷信號為脈沖方式。讓PCF8563每秒鐘在/INT端產(chǎn)生一個脈沖給單片機,在中斷服務(wù)程序中可以讀取時鐘以供顯示。以此時鐘來作為發(fā)射系統(tǒng),接收系統(tǒng)的同步時標(biāo)。無線同步技術(shù)的實現(xiàn)利用了具有豐富的位時鐘信息的曼徹斯特編碼。在發(fā)送數(shù)據(jù)時,主控機將恒溫晶振和電磁信號的數(shù)據(jù)字節(jié)逐個送往編碼模塊,由編碼模塊將其轉(zhuǎn)換成曼徹斯特碼。再經(jīng)過平滑濾波調(diào)整、功率驅(qū)動及音頻變壓器隔離后,送到發(fā)射系統(tǒng)發(fā)射。接收過程是解碼器收到發(fā)射端傳來的信號后,首先將信號經(jīng)過音頻變壓器隔離,再通過帶通濾波、放大整形為矩形波信號,然后送入解碼模塊進行解碼處理,解碼器通過“結(jié)束標(biāo)志字節(jié)”判斷信號是否為有效信號。解調(diào)出的數(shù)據(jù)通過中斷請求方式實現(xiàn)MCU讀取。GPS同步技術(shù)的實現(xiàn)是,GPS接收模塊通過天線接收衛(wèi)星傳送的授時信息,獲得需要的時間信號,該信號和UTC國際標(biāo)準(zhǔn)時間高精度同步,同時,還要校正恒溫晶振的秒脈沖。在FPGA中設(shè)計能夠測量GPS秒時鐘與恒溫晶振秒信號之間誤差的測量模塊,主控機對數(shù)據(jù)進行存儲與處理,利用測量的時間差序列,對GPS信號的隨機誤差的統(tǒng)計方差進行估計,恒溫晶振輸出信號做實時校正,從而產(chǎn)生高精度的時鐘信號。由于同步采樣裝置在強電磁環(huán)境中長期連續(xù)工作,所受到的干擾比較嚴(yán)重,若不能及時正確處理,可能使裝置工作不正常,造成同步采樣的失敗。所以,同步采樣的抗干擾設(shè)計是十分必要的。本文中對于同步采樣裝置抗干擾措施,數(shù)據(jù)采集部分抗干擾措施,及抑制外部電磁噪聲干擾進行了研究,有效減少了同步采樣系統(tǒng)中的干擾。本文在實驗時利用GPS同步技術(shù),充分融合GPS秒時鐘信號優(yōu)良的長期穩(wěn)定特性與恒溫晶振優(yōu)良的短期穩(wěn)定特性,將兩者的長處有機的結(jié)合起來,對GPS信號進行一定處理后,用于校正恒溫晶振輸出,實現(xiàn)一個高精度的時鐘系統(tǒng),使得時鐘精度即使在GPS信號失效3個小時仍能保持小于±1μs,為半航空電磁測量系統(tǒng)供應(yīng)精確的時間標(biāo)準(zhǔn)。本文中的方法與傳統(tǒng)采用GPS脈沖信號調(diào)節(jié)壓控晶振的電壓來修正晶振輸出頻率獲得同步時鐘相比,同步精度得到提高,同步時序調(diào)節(jié)更加方便,通用性強,更加適合在野外工作的半航空瞬變電磁探測系統(tǒng)使用。
[Abstract]:With the rapid increase in the human demand for mineral resources, the contradiction between the limited mineral resources and the growing demand of human beings has become increasingly prominent, which has gradually changed the focus of prospecting work into hidden areas, deep areas and the periphery of mining areas to find hidden ore and blind ore. Semi aeronautical transient electromagnetism method has developed rapidly in the field of electrical prospecting in recent years. An important method. The transient electromagnetic method is a method of using an ungrounded return line or a grounding galvanic source to send a field to the ground, and the method of using a return line or electric dipole to observe two eddy current fields during the interval of a field. The time of "eddy current" from the generation to the end of the transient electromagnetic exploration method is ten minutes short, and the sampling time is very accurate. To do this, the emission current must be closed and measured at a precise time, so the receiving system and the launching system must be accurately synchronized. This paper is based on the research project of the public welfare industry of the Ministry of land and resources "semi aeronautical transient electromagnetic exploration based on unmanned aerial vehicle", mainly to its data acquisition system. The sampling signal synchronization technology between the ground launching system, the ground receiving system and the unmanned aerial vehicle receiving system is studied. This paper mainly studies the principle and implementation of three synchronization technologies, oscillator synchronization, wireless synchronization and GPS synchronization, and uses GPS synchronization technology in the semi aero electromagnetic measurement system. At the same time, the anti-interference measures of the system are studied and applied. The oscillator synchronization technology uses the programmable clock output of the clock chip PCF8563, the alarm and the timer function, and sets the TI/TP=1. At this time, the interrupt signal is pulse mode. PCF8563 produces a pulse at / at the INT terminal per second to the single chip microcomputer, in the interrupt service. In the program, the clock can be read for display. The clock is used as the transmitting system and the synchronization time mark of the receiving system. The implementation of the wireless synchronization technology uses the Manchester code with rich bit clock information. In sending data, the master controller sends the data bytes of the constant temperature crystal and electromagnetic signals to the coding module one by one, and the encoding is coded. The module converts it into the Manchester code. After the smoothing filter is adjusted, the power drive and the audio transformer are isolated and sent to the launch system. The receiving process is the signal that the decoder receives the transmitting end. First, the signal is isolated from the audio transformer, and then the band pass filter is used to shape the signal into a rectangular wave signal and then send it into the solution. The code module performs decoding processing. The decoder determines whether the signal is a valid signal through the "end mark bytes". The demodulated data is realized by the interrupt request mode to realize the MCU reading.GPS synchronization technology. The GPS receiving module receives the time message transmitted by the satellite through the antenna, and obtains the required time signal, the signal and the UTC international. The standard time is high precision synchronization, and at the same time, the second pulse of the constant temperature crystal oscillator should be corrected. In the FPGA, the measurement module that can measure the error between the GPS second clock and the constant temperature crystal second signal is designed. The main control machine stores and processes the data and estimates the statistical variance of the random error of the GPS signal by the time difference sequence of the measured, and the constant temperature crystal. When the synchronous sampling device works in a strong electromagnetic environment for a long time, the interference of the synchronous sampling device is more serious. If it can not be properly handled in time, it may cause the device to work unnormally and cause the failure of synchronous sampling. Therefore, the anti-interference design of synchronous sampling is very necessary. In this paper, the anti-interference measures of synchronous sampling device, the anti-interference measures of the data acquisition part and the suppression of the external electromagnetic noise interference are studied in this paper, which effectively reduces the interference in the synchronous sampling system. In this paper, the GPS synchronization technology is used in the experiment to fully fuse the good long-term stability characteristics and the constant temperature crystal vibration of the clock signal in GPS seconds. The good short-term stability characteristics, combining the strengths of both of the two, after a certain processing of the GPS signal, is used to correct the output of the constant temperature crystal vibration and achieve a high precision clock system. The clock precision can remain less than + 1 s even when the GPS signal is invalid for 3 hours, and the precise time is supplied for the semi aero electromagnetic measurement system. The method in this paper is compared with the traditional GPS pulse signal adjusting the voltage of the voltage controlled crystal oscillator to amend the output frequency of the crystal oscillator to get the synchronization clock, and the synchronization precision is improved. The synchronization timing adjustment is more convenient and versatile. It is more suitable for the use of the semi Aeronautical transient electromagnetic detection system working in the field.

【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P631.326

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本文編號：1855133