Guide to Spectrum and Signal Analysis

Guide to Spectrum and Signal Analysis
Pages 56
Views 867
Downloads : 5 times
PDF Size : 6.6 MiB

Summary of Contents

Guide to Spectrum and Signal Analysis

  • www.anritsu.com | 23If the modulation factor is high enough, we can use the spectrum analyzer as a fixed tuned receiver as follows:a) set the carrier to the center of the display.b) ensure that the resolution bandwidth and the video bandwidth are sufficiently wide enough to en compass the modulation sidebands without attenuation.c) select zero span and adjust the reference level so that the peak of the signal is near to the top of the screen.d) select linear display mode, video triggering and adjust the sweep time to display several cycles of the demodulated waveform.From this display we can measure the modulation factor, m, and the modulating frequency using the analyzers delta marker function (Figure 27).Note: Since this is a relative measurement, as we adjust the reference level of the analyzer, the absolute values of Emax and Emin change but the ratio remains constant. Using the delta marker function will yield the ratio E so by modifying the equation for m we can use this ratio directly.Figure 27m = (1 – (Emin / Emax))(1 + (Emin / Emax))