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 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.

From the RF Freq menu, you can press the Set Carrier To Center submenu key. This adjusts the signal position within the sweep window.

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, you can press the RF Spectrum submenu key to view the signal spectrum. Press the submenu 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 audio spectrum. Press the submenu again to set the signal span or sweep scale.

9.	From the Measurements menu, you can press the Audio Waveform submenu key to view the audio waveform. Press the submenu again to set the sweep time or sweep scale.

In this view, you can see the PL tone (or CTCSS tone) at the leading edge of the signal.

10.	From the Measurements menu, you can 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, you can 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 a table format.

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.

 

 

Copyright 2010 Anritsu Company
	Anritsu Company
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