Timebase Calibration

Use the Timebase tab of the Calibration dialog to perform a calibration that measures a reference clock signal and saves calibration factors to compensate for errors in the measurement system such as variations due to ambient temperature. The calibration results in the best instrument precision. Click Tools > Calibrations to open this dialog.

The available Timebase calibrations are shown in the dialog as shown in this picture.

Calibration Status Icons Icon Description Calibration is current Calibration is recommended Calibration has never been performed

Mainframe Factory Timebase Calibration

The mainframe timebase calibration can only be performed when the DCA-X is returned to a Keysight service center (Qualified Keysight service personnel only). The date when this calibration was last performed is shown along with the change in temperature since the calibration. Mainframe timebase calibration is used to calibrate the input trigger hysteresis and timebase of the mainframe. The calibration data is stored on the instrument hard disk and is used to ensure accurate measurements. The mainframe timebase calibration is required when:

• A change in the temperature of the mainframe exceeds 15°C compared to the temperature of the last mainframe timebase calibration (ΔT > 15°C).
• There is a hardware problem.
• The factory calibration is damaged.

Mainframe User Timebase Calibration

Performs an DCA-X user timebase calibration. The DCA-X must have option ETR, Enhanced Trigger. Although you can quickly and easily perform this calibration at any time, the mainframe user timebase calibration is recommended when a change in the temperature of the mainframe exceeds 5°C compared to the temperature of the last mainframe timebase calibration (ΔT > 5°C) or when the time since the last calibration has exceeded 1 year.

To run the calibration:

1. Install an electrical module into the DCA-X and wait for the mainframe's temperature to stabilize.
2. Connect the output of a clock source to a power splitter with one splitter output going to an electrical module's channel input.
3. Connect the power splitter's other output to the DCA-X 's front-panel Trigger input.Turn all other channels off.
4. Set the clock source to 10 GHz.
5. Start the calibration.

When the calibration completes, a calibration file is stored in the following folder:

C:\ProgramData\Keysight\FlexDCA\Calibration\UserTimebase_N1000A_MY01234567.xml

The file name includes the DCA-X's serial number. To delete the current user timebase calibration, click the Clear button.

Internal Precision Timebase Calibration

If the DCA-X has option PTB (Internal Precision Timebase) installed, you will see this calibration listed in this dialog. No connections are required for performing the calibration. Information in the dialog shows if a calibration is needed. Click a Calibrate button to run the calibration. A module calibration (Module tab) should be run before a starting a Timebase calibration.

 

N109X-Series DCA-Ms Timebase Calibration Procedure

The N109X-series DCA-Ms have their own timebase. If an N109X-series DCA-M is present, the calibration will be listed in this Calibration dialog. The calibration for each N109X-series DCA-M is clearly labeled by input channel.

To run the calibration:

1. Remove all inputs to the N109X-series DCA-M and click Calibrate in the dialog.
2. Wait until the first part of the test completes.
3. Connect a calibration signal to the DCA-M:
1. For an N1090A, when prompted connect a sine wave through a power splitter to the Clock In and Timebase Calibration input connectors as shown in the following picture. The sine wave must be 20.000000 GHz (accurate to at least the nearest 1 kHz) and between 200 mVp-p and 700 mVp-p.

2. For all N1092X-series DCA-Ms, connect a 26.000000 GHz clock signal to Chanel 1A and to the Clock In connector. The signal's amplitude must be between 500 μW p-p and 3.5 mW p-p. In the displayed dialog, specify the wavelength of the signal: 1310 nm or 1550 nm.

You must use a calibrated microwave or vector signal generator. Do not use a pattern generator or arbitrary waveform generator.

4. Confirm that the signal is the correct amplitude by observing the Vp-p measurement on the displayed sine wave. If the signal is out of the required range, the calibration will abort and a message will be displayed. On an N1090A, the color of the waveform matches the color of the DCA-M's front-panel light (next to the Timebase Calibration input).
5. Click Continue.