External Phase Modulation Frequency Response

ΦM deviation frequency response verifies the phase-modulation deviation flatness while varying the modulation rate. A reference value is taken at a 1 kHz rate.

A measurement receiver is used to measure the FM deviation. The FM deviation is then divided by the modulation rate to determine the ΦM Deviation.

ΦM deviation frequency response is checked for CW frequencies 550 MHz and 1.0 GHz. If the DUT meets the specification in this frequency range, accuracy in all other frequency ranges will be assured. Each frequency is tested with the following sequence:

  1. A reference signal is measured.

  2. The set deviation measurement is measured for each applied rate change.

  3. Each deviation measurement is compared to the reference signal deviation.

Instrument

Critical Specifications for This Test

Recommended Model

Measuring Receiver

FM Deviation Accuracy

8902A

Function Generator

none

33120A Opt 001,  33250A

Digital Voltmeter

AC True-RMS Accuracy

3458A

 

Connections and Setup Procedures

All test equipment requires a 30 minute warm-up period to ensure accurate performance.

In the following test setup, direct cable and adapter connections are designated as solid lines. Changeable cable and adapter connections are designated as dashed lines.

 

  1. Connect all test equipment as shown.

  2. Connect GPIB cables to all GPIB-controlled test equipment.

  3. While performing this test, follow all instructions on the controller display.
     

Measuring Receiver Calibration Setup


 

Phase Modulation Frequency Response Test Setup