144Demodulating AM SignalsMeasuring the Modulation Index of an AM SignalMeasuring the Modulation Index of an AM SignalThis procedure demonstrates how to use the signal analyzer as a fixed-tuned(time-domain) receiver to measure the modulation index as a percent AM value of anAM signal.Step Action Notes1 Set up the signal source. a. Set the source frequency to300 MHz.b. Set the source amplitudes to−10 dBm.c. Set the AM depth to 80%.d. Set the AM rate to 1 kHz.e. Turn AM on.2 Connect an KeysightESG RF signal source tothe analyzer RF INPUTas shown.3 Select the mode. • Press Mode, SpectrumAnalyzer.4 Preset the analyzer. • Press Mode Preset.5 Set the center frequency,span, RBW and thesweep time.a. Press FREQ Channel,Center Freq, 300, MHz.b. Press SPAN X Scale, Span,500, kHz.c. Press BW, Res BW, 30,kHz.d. Press Sweep/Control,Sweep Time, 20, ms.
