![]() However, another large group of measurements can be made without knowing the phase relationships among the sinusoidal components. Some measurements require that we preserve complete information about the signal frequency, amplitude, and phase. If the signal we wish to analyze is periodic, as in our case here, Fourier says that the constituent sine waves are separated in the frequency domain by 1/T, where T is the period of the signal. Each sine wave is characterized by its amplitude and phase. With proper filtering, a waveform such as the one shown in Figure 1-1 can be decomposed into separate sinusoidal waves, or spectral components, which we can then evaluate independently. Measurements in the frequency domain tell us how much energy is present at each particular frequency. In other words, we can transform a time-domain signal into its frequency-domain equivalent. In other words, we use the oscilloscope to view the waveform of a signal in the time domain.įourier1 theory tells us any time-domain electrical phenomenon is made up of one or more sine waves of appropriate frequency, amplitude, and phase. We can use an oscilloscope to view the instantaneous value of a particular electrical event (or some other event converted to volts through an appropriate transducer) as a function of time. Introduction - What Is A Spectrum Analyzer?īefore we get into the details of describing a spectrum analyzer, we might first ask ourselves: “Just what is a spectrum and why would we want to analyze it?” Our normal frame of reference is time. In this note, we describe the basic spectrum analyzer as well as additional capabilities made possible using digital technology and digital signal processing. ![]() With the advent of digital technology, modern spectrum analyzers have been given many more capabilities. As long as we know some value of a sine wave (for example, peak or average) and know the resistance across which we measure this value, we can calibrate our voltmeter to indicate power. It is important to understand that the spectrum analyzer is not a power meter, even though it can be used to display power directly. This application note explains the fundamentals of swept-tuned, superheterodyne spectrum analyzers and discusses the latest advances in spectrum analyzer capabilities.Īt the most basic level, a spectrum analyzer can be described as a frequency-selective, peak-responding voltmeter calibrated to display the rms value of a sine wave. ![]()
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