更好测量频谱的8点建议Agilent AN 1286-1 Hints for making Better Spectrum Analyzer Measurements The Heterodyne Spectrum Analyzer The spectrum analyzer, like an oscilloscope, is a basic tool used for observing signals. Where the oscilloscope provides a window into the time domain, the spectrum analyzer provides a window into the frequency domain, as depicted in Figure 1. Figure 2 depicts a simplified block diagram of a swept-tuned spectrum analyzer. In the analyzer, a signal at the input first travels through the attenuator and the low-pass input filter. The attenuator then limits the amplitude of the signal, while the filter eliminates undesirable frequencies. Past the input filter, the signal gets mixed with another signal generated by a voltage controlled oscillator (VCO). The frequency of the VCO is con……