DCFM Calibration (Adjustment)

(N5161A / N5162A / N5181A / N5182A) (Option UNT)

This adjustment calibrates the FM offset by calling the firmware DCFM cal and storing the result in the cal array.

The firmware DCFM cal is performed by the presto modulation filter. The calibration removes all DC offsets from the modulation-path multiplexer to the ADC. This is done by connecting the input of modulation ADC to the ground (through the modulation-path multiplexer) and then letting the presto modulation filter capture DC offset.

Required Test Equipment

Test Equipment

Recommended Model

Alternate Model(s)

Spectrum Analyzer

PXA N9030B Option Pxx1

 

PXA N9030A Option Pxx1

PSA models Option [1DS or 110]1:
E4440A
E4443A
E4445A
E4446A
E4447A
E4448A

  1. Preamp option (Pxx for PXA, 1DS or 110 for PSA) is recommended but not required.

 

Connections and Setup Procedures
  • All test equipment requires a 30 minute warmup period to ensure accurate performance.
  • In the following setup, cables are designated as solid lines and direct connections are designated as dashed lines.

Initialize Test Equipment

  1. Connect all test equipment as shown.
  2. Preset all test equipment and the signal generator.

 

Setup for DCFM Calibration

In Case of Difficulty

If this adjustment fails, perform the following steps in order:

  1. Check the equipment setup (see above). If the setup is incorrect, make the necessary corrections and rerun the adjustment.

  2. Check for DC offsets after the modulation path multiplexer.

  3. Refer to the troubleshooting section of the service guide. If you do not have a printed copy of the service guide (Option OBW), one is available either on the CD-ROM that came with your signal generator shipment or on the Keysight website.

  4. If necessary, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.