External Phase Modulation Frequency Response

ΦM deviation frequency responseverifies 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.

Required Test Equipment

Instrument

Critical Specifications for This Test

Recommended Model1

Spectrum Analyzer

FM Deviation Accuracy

E444xA2 Opt 1DS, 1233

Function Generator

none

33250A

Digital Voltmeter

AC True-RMS Accuracy

3458A Opt 002
  1. Refer to the main equipment list for alternate models.
  2. Depending on your frequency range needs, choose either an E4440A, E4443A, E4445A, E4446A, or E4448A. (E4447A is for Power Level Accuracy adjustment only.)
  3. Options 1DS and 123 are for ESGs > 3 GHz.

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.
  • Connect all test equipment as shown.
  • Connect GPIB cables to all GPIB-controlled test equipment.
  • While performing this test, follow all instructions on the controller display.

 

Measuring Receiver Calibration Setup


 

Phase Modulation Frequency Response Test Setup