Spectrum Analyzer Measurement Guide : AM/FM/PM Analyzer (Option 509) : General Measurement Setup
 
General Measurement Setup
Refer to your instrument User Guide for instructions on setting up frequency, span, amplitude, GPS, limit lines, markers, and file management.
1. Connect an antenna that is suitable for the measurements.
2. If the instrument is currently in a different measurement mode, switch to AM/FM/PM Analyzer mode. Refer to Selecting a Measurement Mode.
3. Press the Setup main menu key, then press the Demod Type submenu key to toggle the setting to AM, FM, or PM signal analysis. The active setting is underlined on the submenu key face.
4. While in the Setup menu, you may choose to set the IFBW (IF Bandwidth) or to turn On or Off the automatic IFBW (by pressing the Auto IFBW submenu key). The available values for IFBW are: 1 kHz, 3 kHz, 10 kHz, 30 kHz, 100 kHz, and 300 kHz.
If the Auto IF BW function is On, then manually changing the IFBW turns it Off. When the Auto IF BW function is On, the IFBW is automatically changed to the closest value that is greater than, or equal to, the span currently set in the Freq main menu. If the span is greater than 300 kHz, then the IFBW is set to 300 kHz.
5. Press the Freq main menu key. You can set the frequency in one of two ways:
1. Press the Center Freq submenu key to set the desired center frequency. In RF Spectrum measurements, press the Set Carrier Freq to Center submenu key to adjust the signal position to the center of the display screen.
Note 
If Demod Type is set to FM or PM, then the Set Carrier Freq to Center function aligns the carrier to center only if the carrier is within the IFBW from the center frequency.
2. Press the Signal Standard submenu key to display the Signal Standards list. Choose a signal standard and press the Enter key. The current signal standard is displayed at the top of the sweep window. The frequency is automatically set when the signal standard is selected.
Press the Channel submenu key to open the Channel Editor dialog and select a channel.
6. Press the Span submenu key and set a span value.
7. Press the Amplitude main menu key to open the RF Amplitude menu. Here you may set the scale or the power offset.
8. Press the Measurements main menu key to open the Measurements menu.
9. From the Measurements menu, choose RF Spectrum, Audio Spectrum, Audio Waveform, or 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.
10. If the RF Spectrum graph displays “ADC error”, then press the Amplitude main menu key and then press Adjust Range. Pressing the Adjust Range submenu key sets the Y‑axis reference level based on the signal strength. If the signal is too large (ADC error) or too low, then pressing this key sets the reference level such that the signal is displayed fully within the sweep window. The peak may be close to second grid from the reference.
11. To listen to the audio component of an AM or FM signal, press the Audio Demod submenu key. Audio demodulation is not available for PM signals.
12. In the Audio Demod menu, press the On / Off submenu key turn On or Off the audio demodulation function. A Demod Type submenu key is available, as well as a Volume submenu key.
13. To save or recall setups or measurements, press the Shift key and the File (7) key. Setup files are saved with a .stp extension, and measurement files are saved with a .afp extension.
14. Setups may also be saved or recalled by pressing the Shift key and the Preset (1) key. Refer to your instrument User Guide for details.