A wave in its complex format is composed of harmonics of different frequencies. It also carries non-harmonic contents like noises. Waveform analyzers and spectrum analyzers are used to measure the amplitudes of different frequencies. The advantage of spectrum analyzer over waveform analyzer is that it provides the graph of the amplitude versus frequency. Logic analyzer is employed for the analysis of digital circuits. In waveform analyzer, Fourier analysis is carried out first and then feeding this to instruments. The components of a waveform analyzer are tuned amplifier voltmeter, heterodyne mixer and variable frequency oscillator. Swept filter technique is an alternative technique where signal which is to be analyzed is passed through a filter whose centre frequency is continuously tunable. Display mode of spectrum analyzer is different from waveform analyzer. The two varieties of spectrum analyzer are selective type spectrum analyzer and swept frequency type spectrum analyzer. A set of band-pass filters are used in selective type spectrum analyzer and an intermediate frequency band-pass filter amplifier is used in swept frequency spectrum analyzer.
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