【摘要】：近年來,氣體污染已經(jīng)成了威脅人們身體健康的因素之一,加強氣體監(jiān)測力度的重要性不言而喻�？烧{(diào)諧半導體激光吸收光譜技術(shù)(Tunable Diode Laser Absorption Spectroscopy,TDLAS)擁有高分辨率,高靈敏度,因此在溫室氣體監(jiān)測中得到廣泛應用,其中的二次諧波檢測技術(shù)在氣體監(jiān)測方面已經(jīng)實現(xiàn)了快速高靈敏度的測量。在TDLAS氣體檢測中需要運用鎖相放大技術(shù)對攜帶有氣體濃度信息的微弱二次諧波信號進行提取。本文針對TDLAS氣體傳感系統(tǒng)設(shè)計了一款鎖相放大器用來提取微弱二次諧波信號。首先介紹了基于TDLAS技術(shù)氣體檢測的相關(guān)原理,包括:紅外光譜吸收原理,TDLAS技術(shù)原理,諧波檢測原理以及數(shù)字鎖相放大器原理,信號的相關(guān)檢測原理。根據(jù)以上原理,利用System Generator建模,對數(shù)字鎖相放大器的各個分模塊進行設(shè)計,包括生成參考正交信號的DDS,乘法器和低通濾波器,對各個模塊分別進行驗證,使用設(shè)計的模塊搭建了雙通道的數(shù)字鎖相放大器模型,并對其進行仿真和功能驗證。其次,基于FPGA使用VHDL語言設(shè)計數(shù)字鎖相放大器各部件,包括DDS模塊,乘法器,分布式低通濾波器,開方模塊等。對每個模塊進行了仿真,在ISE中使用原理圖的設(shè)計方法實現(xiàn)了雙通道的數(shù)字鎖相放大器的設(shè)計。最后,根據(jù)系統(tǒng)的需求選定了Spartan6系列XC6SLX45T型芯片作為我們系統(tǒng)的主芯片,并根據(jù)需求設(shè)計了鎖相放大器的電路板,并把設(shè)計的雙通道數(shù)字鎖相放大器的代碼下載到設(shè)計的電路板中,最后針對具體信號進行了測試,測試結(jié)果表明數(shù)字鎖相放大器能夠很好地提取待測信號的幅值并具有良好的穩(wěn)定性。
[Abstract]:In recent years, gas pollution has become one of the factors threatening people's health, and the importance of gas monitoring is self-evident. Tunable semiconductor laser absorption spectroscopy (Tunable Diode Laser Absorption Spectroscopy,TDLAS) is widely used in greenhouse gas monitoring because of its high resolution and high sensitivity. Among them, the second harmonic detection technology has realized fast and high sensitivity measurement in gas monitoring. The weak second harmonic signal with gas concentration information should be extracted by phase-locked amplification technique in TDLAS gas detection. In this paper, a phase-locked amplifier is designed for TDLAS gas sensing system to extract weak second harmonic signal. Firstly, the related principles of gas detection based on TDLAS technology are introduced, including infrared spectrum absorption principle, TDLAS technology principle, harmonic detection principle, digital phase-locked amplifier principle and signal correlation detection principle. According to the above principle, using the System Generator modeling, each sub-module of the digital phase-locked amplifier is designed, including the DDS, multiplier and low-pass filter that generate the reference orthogonal signal, and each module is verified respectively. A dual channel digital phase-locked amplifier model is built with the designed module, and its simulation and function verification are carried out. Secondly, the digital phase-locked amplifier components are designed based on FPGA using VHDL language, including DDS module, multiplier, distributed low-pass filter, open-square module and so on. Each module is simulated, and the design of dual channel digital phase-locked amplifier is realized by using the schematic design method in ISE. Finally, according to the demand of the system, the Spartan6 series XC6SLX45T chip is selected as the main chip of our system, and the circuit board of the phase-locked amplifier is designed according to the demand. The code of the dual-channel digital phase-locked amplifier is downloaded to the designed circuit board. Finally, the specific signal is tested. The test results show that the digital phase-locked amplifier can extract the amplitude of the signal well and has good stability.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X84

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本文編號：2352299