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4) Press [Amplitude]→[Ref Level] and set the reference level of the RF spectrum. Press [Scale/Div] and set the
appropriate scale/division to facilitate the viewing of RF spectrum.
5) Press [Audio Spectrum]→ [Span] and set the appropriate span. Press [Scale/Div] and set the appropriate
scale/division to facilitate the viewing of the frequency spectrum of the audio signal.
6) Press [Audio Waveform] → [Sweep Time], and set the display time of the audio signal waveform. Press
[Scale/Div] and set the appropriate scale/division to facilitate the viewing of the frequency spectrum of the audio
signal.
Set the appropriate IF bandwidth. The IF bandwidth should be more than the width of the modulation signal, so as to accurately demodulate the signal.
You can observe the bandwidth in the RF spectrum. At the same time, noise may be produced in the case of too large IF bandwidth, which will affect the
accuracy of parameter measurement.
Taking the FM signal measurement for example, the AM-FM-PM analyzer mode is introduced as follows. At first,
input the FM signal generated by one signal source to the RF input end of the instrument. Set the signal frequency
as 6GHz, amplitude as -10dBm, modulation rate as 3kHz and modulation offset as 30kHz. Measurement
procedures are as follows:
1) Press [Measure]→ [Demod Type AM FM PM] and select FM.
2) Press [Freq]→ [Center Freq] and set the center frequency of the measured signal as 6GHz.
3) Press [BW]→ [IFBW] and set the IF bandwidth as 100kHz.
4) Press [Audio Spectrum]→ [Span], and set the span as 50kHz.
5) Press [ [Audio Waveform] → [Sweep Time] and set the sweep time as 2ms.
Measurement results are shown in Fig. 7-1.
