2015毕业论文--简易频谱分析仪的设计.doc

摘 要 频谱分析仪的基本功能是测量信号的幅度/频率响应，可以完成诸如频谱成分分析、失真测量、调制信号谱分析、信号衰减测量、电子组件增益测量等。其基本工作原理是，扫频本振的频率随锯齿波发生器的输出在一定范围内扫描，使不同频率的输入信号与本振混频后，依次落入分辨率带宽滤波器通带内，进一步放大、检波后加到Y放大器，亮点在屏幕上的垂直偏移正比于该频率分量的幅值。由于扫描电压在调制振荡器的同时，又驱动X放大器，从而可以在屏幕上显示出被子测信号的频谱。 本系统是根据外差原理设计并实现的频谱分析仪。利用DDS芯片生成10KHZ步进的本机振荡器，AD835做混频器实现频率的合成，通过滤波器取出各个频点（相隔10KHZ）的值，再配合放大，检波电路收集采样值，经单片机SPCE061A处理，最后送给示波器显示频谱。测量频率范围覆盖1—30MHZ，该系统也可以根据用户的需要设定显示频谱的中心频率和带宽，还可以识别调幅，调频和等幅波信号。 关键词 频谱分析，混频，滤波，外差原理 Abstract Spectrum analyzer to measure the signal is the basic function of the amplitude/frequency response can be finished such as spectrum composition analysis, distortion measuring, modulation signal spectrum analysis, signal attenuation measure, electronic component 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 components. 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 1-30MHZ 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 Spectr