DCFM Frequency Offset

DC FM Carrier Offset is a measure of carrier-frequency shift due to residual DC on the ESG’s EXT1 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.

Instrument

Critical Specifications for This Test

Recommended Model

Frequency Counter

Frequency Resolution ≥ 0.1 Hz at 1 GHz

HP 53131A or HP 53132A,
Opt 010 and [050 or 124]

 

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.