DCFM Carrier Offset

DC FM Carrier Offset is a measure of carrier-frequency shift due to residual DC on the ESG’s EXT 1 DC-coupled path when FM mode is selected. Any DC level in this path will cause a constant offset (deviation) in the CW frequency.

For this test, the ESG is set to a selected carrier frequency and FM is enabled. The EXT 1 input is selected and left open. A specific value of FM deviation is selected and a DC FM calibration is executed.

For FM ON and FM OFF, the carrier frequency is measured with a frequency counter. Any shift in the carrier frequency must be due to a residual DC voltage somewhere in the EXT 1 input path.

Test Equipment

Critical Specifications for This Test

Recommended Models

Alternate Models

Frequency Counter

Frequency Resolution ³ 0.1 Hz at 1 GHz

53230A Opt 106 or 115

53132A Opt 050 or 124
53131A Opt 010 050 or 124

Connections and Setup Procedures

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

In Case of Difficulty

If this performance test fails, perform the following steps in order:

Check the equipment setup (see above). If the setup is incorrect, make the necessary corrections and rerun the performance test.
If this test fails with the equipment set up properly, refer to the troubleshooting section of the signal generator's 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.
If you cannot correct the problem using the troubleshooting procedures in the Service Guide, obtain service from Keysight Technologies. Refer to Contacting Keysight Technologies.