Calibration

3048A Phase Noise Test Set - Calibration

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HP 3048A Phase Noise - Calibration
Display of System Configuration:

Running the 3048 CAL Program to Display the Configuration for the Calibration.

The system to be calibrated will include the 11848A Phase Noise Interface, a 3561A Spectrum Analyzer and a 8662A Synthesizer. This is the minimum possible configuration to run a test from 1 Hz to 100 KHz offset from carrier:

HP 3048 Cal Program Main Menu

HP 3048 Cal Program - Showing System Configuration in Use

HP 3048 Cal Program - Showing Instrument Addresses

HP 3048A Phase Noise - Running the Calibration

Phase noise measurements are ultimately made by the HP 3561A Dynamic Signal Analyzer after the demodulated "noise signal" has passed through the HP 11848A Phase Noise Interface. Phase lock loop control signals also pass through the Interface. The Interface conditions the signals for best measurement sensitivity and accuracy. It is therefore important to know the characteristics of the circuits in this Interface.

The Interface's characteristics are acquired during calibration. The acquired data is stored on the mass-storage media (hard
or floppy disc). During the normal course of operation, the System loads the data into the computer's memory (RAM) where it is accessed by the program as needed to correct the raw measurement data. Therefore, the stored data must match the specific Interface being used. It is a good practice to keep the Interface's serial number in the System's Configuration Table which will then appear on data printouts.

The calibration data is stored in two data files: "CALDATALO" and "CALDATAHI". CALDATALO is used for signal-path circuits through 100 kHz. CALDATAHI is used for signal paths above 100 kHz plus the VNOMs (the nominal tuning voltage of the tunable, internal sources) and noise-flatness data for flatness variations greater than 2 dB.

HP 3048 Cal Program - Select Calibration

HP 3048 Cal Program - Select DC - 100 KHz Calibration

HP 3048 Cal Program - Answer YES for measurement of the external reference path

HP 3048A Phase Noise - Running the Calibration

A number of tests will be run to complete the calibration. At each step, instructions to help system wiring will be displayed as shown in the following pictures.

HP 3048 Cal Program - Wiring for the 3561A calibration

HP 3048 Cal Program - Wiring for the 2nd sequence of calibration

HP 3048 Cal Program - Wiring for the last sequences of calibration

HP 3048A Phase Noise - Calibration
Storing the Calibration Data on the Controller Hard Disk

At the end of the calibration sequences the program will ask to store the calibration data on the Hard Disk of the controller.

HP 3048 Cal Program - Storing the Cal Data

HP 3048 Cal Program - Choose Path (where to store the calibration data files)

HP 3048A Phase Noise - Calibration
Displaying the Calibration Data

When the calibration is completed, it is possible to display a set of curves giving an overview of the various correction parameters defined during the calibration process.

HP 3048 Cal Program - Choose Evaluate Cal Data in the calibration menu