【摘要】：近年來(lái),氣體污染已經(jīng)成了威脅人們身體健康的因素之一,加強(qiáng)氣體監(jiān)測(cè)力度的重要性不言而喻�？烧{(diào)諧半導(dǎo)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(cè)中得到廣泛應(yīng)用,其中的二次諧波檢測(cè)技術(shù)在氣體監(jiān)測(cè)方面已經(jīng)實(shí)現(xiàn)了快速高靈敏度的測(cè)量。在TDLAS氣體檢測(cè)中需要運(yùn)用鎖相放大技術(shù)對(duì)攜帶有氣體濃度信息的微弱二次諧波信號(hào)進(jìn)行提取。本文針對(duì)TDLAS氣體傳感系統(tǒng)設(shè)計(jì)了一款鎖相放大器用來(lái)提取微弱二次諧波信號(hào)。首先介紹了基于TDLAS技術(shù)氣體檢測(cè)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(cè)原理以及數(shù)字鎖相放大器原理,信號(hào)的相關(guān)檢測(cè)原理。根據(jù)以上原理,利用System Generator建模,對(duì)數(shù)字鎖相放大器的各個(gè)分模塊進(jìn)行設(shè)計(jì),包括生成參考正交信號(hào)的DDS,乘法器和低通濾波器,對(duì)各個(gè)模塊分別進(jìn)行驗(yàn)證,使用設(shè)計(jì)的模塊搭建了雙通道的數(shù)字鎖相放大器模型,并對(duì)其進(jìn)行仿真和功能驗(yàn)證。其次,基于FPGA使用VHDL語(yǔ)言設(shè)計(jì)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(kāi)方模塊等。對(duì)每個(gè)模塊進(jìn)行了仿真,在ISE中使用原理圖的設(shè)計(jì)方法實(shí)現(xiàn)了雙通道的數(shù)字鎖相放大器的設(shè)計(jì)。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(jì)了鎖相放大器的電路板,并把設(shè)計(jì)的雙通道數(shù)字鎖相放大器的代碼下載到設(shè)計(jì)的電路板中,最后針對(duì)具體信號(hào)進(jìn)行了測(cè)試,測(cè)試結(jié)果表明數(shù)字鎖相放大器能夠很好地提取待測(cè)信號(hào)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(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X84

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本文編號(hào)：2352299