Spectrum Analyzer Measurement Guide : AM/FM/PM Analyzer (Option 509) : Example FM Demodulation Measurement
 
Example FM Demodulation Measurement
1. Press the Setup main menu key and then press the Demod Type submenu key to toggle the setting to FM. The active setting is underlined on the submenu key face.
2. Press the Auto IFBW submenu key to set the IFBW (IF Bandwidth) frequency automatically. The active setting is underlined on the submenu key face.
3. Press the IFBW submenu key to set the value manually. Doing so will automatically turn Off the Auto_IFBW function. The available values for IFBW are: 1 kHz, 3 kHz, 10 kHz, 30 kHz, 100 kHz, and 300 kHz.
4. Press the Freq main menu key to set the center frequency, the span, the signal standard, or the channel.
5. Press the Amplitude main menu key to set the scale or the power offset. From the RF Amplitude menu, you can also press the Adjust Range submenu key.
6. Press the Measurements main menu key to choose the desired type of measurement.
7. From the Measurements menu, press the RF Spectrum submenu key to view the signal spectrum. Press the submenu key again to set specific signal measurement functions.
a. Press the Occ BW Method submenu key to select the preferred method of presenting the occupied bandwidth, either by percent of the total received signal power or by an amount better than the dBc that is set with the dBc submenu key.
b. Use the other two submenu keys as needed for signal presentation.
8. Press the Audio Spectrum submenu key to view the spectrum of the demodulated audio. Press the submenu key again to set the span for the audio spectrum or the squelch level. Note that RF signals below the squelch level will cause the audio spectrum to be a flat line in the center of the screen.
In this view, you can see the 19 kHz stereo pilot tone as well as other subcarriers.
Audio Spectrum
9. From the Measurements menu, press the Audio Waveform submenu key to view the audio waveform. Press the submenu key again to set the sweep time for the audio waveform display, or the squelch level. Note that RF signals below the squelch level will cause the audio waveform to be a flat line in the center of the screen.
Audio Waveform
10. From the Measurements menu, press the Audio Demod submenu key to listen to the audio component of the FM signal. In this menu, you can choose wideband or narrowband demodulation, set the demodulation time, and you can also set the instrument speaker volume.
11. Press the Summary submenu key to view all of the signal characteristics in table format. Press the submenu key again to set the summary average or the squelch level.
Audio Summary
Note 
Measurement values for SINAD, THD, and Distortion/Total apply only to single tone modulation. For better accuracy of these measurements, the modulation rate should be at least 0.7 % of IFBW. For Distortion Measurements, the IFBW should be at least twice the maximum modulation rate + deviation.
If the modulation source is not single tone, you can turn off these measurements by pressing the Distortion Measurements submenu key to select the Broadcast setting.
12. For instruments that also have Option 431 installed, press the Coverage Mapping submenu key to set up mapping of Signal‑to‑Noise and Distortion (SINAD) ratio and/or Carrier Power. Refer to Figure: Mapping of AM Signal SINAD and Carrier Power. for an example of coverage mapping. After coverage mapping is turned on, press Measurement Setup to select SINAD and/or Carrier Power and set the threshold levels.
Note 
Frequency, Demod Type, IF Bandwidth and Threshold levels can also be changed using the touch screen.
The menu structure for coverage mapping is shown starting in AM / FM / PM Analyzer Menus.
Refer to Coverage Mapping (Option 431) for an overview of the coverage mapping four-step process:
Create an indoor or outdoor map using Anritsu easyMap Tools.
Load the map and configure the Instrument Settings.
Connect an antenna to the instrument and go to Map the Signal Strength.
Save the Coverage Mapping Information.
Mapping of AM Signal SINAD and Carrier Power.
 
Note 
AM/FM/PM Coverage mapping uses AM/FM/PM Analyzer mode not Spectrum Analyzer mode.