Sweep Time Limitations With Power Spectrum Measurements

Sweep time is the time required for the application to complete one full sweep on the display.

With the standard swept-tuned analyzer, sweep time is limited by analog IF filter dynamics because the filter must have time to respond to the input signal before accurately measuring a frequency. When performing Power Spectrum measurements with 89600 VSA software, the digital IF and FFT Fast Fourier Transform: A mathematical operation performed on a time-domain signal to yield the individual spectral components that constitute the signal. See Spectrum. act like a parallel filter bank. This means the sweep speed is limited by data collection and digital processing time rather than filters (there are digital filters in the digital IF which do require some settling time, but this is negligible when compared to the settling time of analog filters). For this reason, Power Spectrum measurements for low-resolution bandwidths can run much faster than would be the case with a swept analyzer. The sweep time is adjusted automatically as the analyzer selects the optimum sweep time based on the frequency span, window, resolution bandwidth, and other parameters.