【正文】 簡易頻譜分析儀的設計 I 摘 要 頻譜 分析 儀的基本功能是測量信號的幅度 /頻率響應，可以完成諸如頻譜成分分析、失真測量、調(diào)制信號譜分析、信號衰減測量、電子組件增益測量等。 其 基本工作原理是，掃頻本振的頻率隨鋸齒波發(fā)生器的輸出在 一定范圍內(nèi)掃描，使不同頻率的輸入信號與本振混頻后，依次落入 分辨率 帶寬濾波器通帶內(nèi)，進一步放大、檢波后加到 Y 放大器，亮點在屏幕上的垂直偏移正比于該頻率分量的幅值。由于掃描電壓在調(diào)制振蕩器的同時，又驅(qū)動 X放大器，從而可以在屏幕上顯示出被子測信號的頻譜。 本 系統(tǒng)是根據(jù) 外差原理設計并實現(xiàn) 的 頻譜分析儀。利用 DDS 芯片生成 10KHZ步進的本機振蕩器， AD835 做混頻器 實現(xiàn)頻率的合成 ，通過濾波器取出各個頻點（相隔 10KHZ）的值，再配合放大，檢波電路收集采樣值，經(jīng)單片機 SPCE061A 處理，最后送 給 示波器顯示頻譜。測量頻率范圍覆蓋 1—30MHZ， 該系統(tǒng)也 可 以 根據(jù)用戶 的 需要設定顯示頻譜的中心頻率和帶寬，還可以識別調(diào)幅，調(diào)頻和等幅波信號。 關鍵詞 頻譜分析 ，混頻 ， 濾波， 外差原理 沈陽工程學院畢業(yè)設計（論文） II Abstract Spectrum analyzer to measure the signal is the basic function of the amplitude/frequency response can be finished such as spectrum position analysis, distortion measuring, modulation signal spectrum analysis, signal attenuation measure, electronic ponent gain measurements. Basic working principle is, sweep frequency this the vibration of the frequency with the output of sawtooth wave generator in a certain range of different frequency scanning, make the input signal and the resonance frequency mixing, ordinal fall within bandpass filter bandwidth resolution, further amplification, after detection of amplifier, highlights added to Y in screen is proportional to the vertical migration of the amplitude frequency ponents. Due to scan voltage in modulation oscillator, and meanwhile, thus can drive X amplifier is shown on the screen in the spectrum of the measured signal quilt. This paper adopts heterodyne principle design and realize the spectrum analyzer. Use 10KHZ DDS chip generation step of this machine oscillators, AD835 do mixers, through the filter remove each frequency (10KHZ) value apart, coupled with amplifier, detection circuit to collect samples values of sunplus SPCE061A processing by MCU, finally send oscilloscope display spectrum. Measure frequency range covers 130MHZ according to user need to set the display spectrum of center frequency and bandwidth, still can identify am, FM and amplitude wave signal. KEY WORDS Spectral analysis, mixing, smoothing, heterodyne principle 簡易頻譜分析儀的設計 III 目錄 摘 要 ......................................................................................................................................... I Abstract ....................................................................................................................................II 1 緒 論 ............................................................................................................................... 1 頻譜分析儀的簡介 ............................................................................................... 1 總體設計方案比較 ............................................................................................... 2 底層電路方案比較與選擇 ................................................................................... 2 本機振蕩電路 .............................................................................................. 2 混頻電路 ..................................................................................................... 3 濾波電路 ..................................................................................................... 3 檢波電路 ..................................................................................................... 3 掃頻發(fā)生器電路 ......................................................................................... 4 本課題研究的意義 ............................................................................................... 4 本課題設計思路 ................................................................................................... 4 2 頻譜分析儀的硬件設計 ................................................................................................. 6 頻譜分析儀的整體結構 ....................................................................................... 6 頻譜分析儀的各模塊電路設計 ........................................................................... 7 本機振蕩器模塊 ......................................................................................... 7 混頻器模塊 ................................................................................................. 9 放大器模塊 ................................................................................................. 9 濾波器模塊 ............................................................................................... 10 檢波器模塊 ............................................................................................... 12 掃頻發(fā)生器模塊 ....................................................................................... 13 電源保護模塊 ........................................................................................... 16 3 軟件設計 ....................................................................................................................... 18 軟件設計要求 ..................................................................................................... 18 主程序的軟件設計 ............................................................................................. 18 4 系統(tǒng)調(diào)試與指標測試 ................................................................................................... 20 硬件調(diào)試 ............................................................................................................. 20 軟件調(diào)試 ............................................................................................................. 20 軟硬聯(lián)合調(diào)試 ..................................................................................................... 20 指標測試 ............................................................................................................. 20 儀器測試 .....