Calibration

• Overview

• Performing Calibration

• Defining Calibration Kits

• Standard Definitions

• Reading/Writing Calibration Coefficient Alone

• Clearing Calibration Data and Calibration Coefficients

Other topics about Performing Calibration

Overview

You need to execute calibration to eliminate error elements related to measurement, thus allowing you to perform accurate measurement.

Performing Calibration (Obtaining calibration coefficients)

Selecting a Calibration Kit

To select a calibration kit, use the following command:

:SENS{1-160}:CORR:COLL:CKIT

Selecting a Calibration Type

The calibration coefficients are calculated based on the selected calibration type. Therefore, before you can calculate the calibration coefficients, you must select the appropriate calibration type by using one of the following commands.

• To calculate the calibration coefficients for the simplified full 3-port and simplified full 4-port calibrations, select the full 3-port and full-4 port commands, respectively. To calculate the calibration coefficient for the simplified 3-port TRL calibration and the simplified 4-port TRL calibration, select the 3-port TRL and the 4-port TRL commands, respectively.

To check the currently selected calibration type, use the following command:

:SENS{1-160}:CORR:COLL:METH:TYPE?

Setting the trigger source for calibration

To set the trigger source for calibration, use the following command. By setting the trigger source for calibration to "System," setting the trigger source for measurement to "External," and turning on the point trigger function, it becomes possible to use "calibration for each measurement point using the external trigger."

:SENS{1-160}:CORR:TRIG:FREE

• The trigger source for calibration does not function for the calibrations of E-Cal, power, receiver, and scalar mixer.

Measuring Calibration Data

To measure the calibration data, use one of the following commands:

• You cannot run more than one of the commands listed above at a time; if you issue another command before the currently running command completes successfully, the current command will be aborted. Therefore, when you write a program that issues multiple calibration commands in series, you should use the *OPC? command or some other means to ensure that no command is executed before the preceding command completes itself.

As shown in the table below, the data required to calculate the calibration coefficients differ depending on the selected calibration type.

In the data section in the table, the letter m (for example, 1, a) represents the measurement data at port m; m-n (for example, 1-2, a-b) represents the measurement data between response port m and stimulus port n. You can omit data enclosed in brackets.

Calculating Calibration Coefficients

To calculate the calibration coefficients, use one of the following commands:

Before issuing the above commands, you must measure all required calibration data items according to your selected calibration type. Calculating the calibration coefficients clears all calibration data regardless of whether they are used for the calculation. The calibration type selection is also cleared, which results in a state where no calibration type is selected.

Simplified full 3-/4-port calibration

• This function is available with Firmware revision 3.50 or greater. Note that you can execute this function from the front panel only for Firmware revision A.06.50 or greater.

The simplified full 3-/4-port calibration acquires the calibration coefficients while omitting a part of the thru measurement.

Notes on the simplified full 3-/4-port calibration

Compared to the normal full 3-/4-port calibration, the simplified full 3-/4-port calibration is more sensitive to the error that may arise when acquiring calibration data. This because the calibration coefficients are calculated without a part of the thru measurement data. Therefore, the following should be considered when measuring data for the simplified full 3-/4-port calibration.

• The standard used for measurement must match its definition value.

• • Use a standard that provides good repeatability (stability).

  • Do not omit the length of the thru when defining the standard.

  • When using a user-created standard, verify the definition value.

  • For the N connector, remember that it has two different types: male and female.

• Assure high reliability and repeatability for measurement.

• • Reduce the difference in external environment (such as temperature difference) between the time when measuring calibration data and when measuring actual data.

  • Set the power level of the stimulus signal sufficiently small so that compression does not occur.

  • Narrow the IF bandwidth.

  • Increase the averaging factor.

  • Use a cable that has robust amplitude/phase characteristics against bending.

  • Use high-precision connectors.

Simplified 3/4-port TRL calibration

• This function is available with Firmware revision A.06.50 or greater.

• The simplified 3/4-port TRL calibration calculates the calibration coefficient by skipping part of the thru/line measurement (or line/match measurement) that is necessary for normal 3/4-port TRL calibration.

• You need to give consideration to the same conditions for the simplified 3/4-port TRL calibration as those for the simplified full 3/4-port calibration listed above.

Turning ON/OFF Error Correction

To turn ON/OFF error correction, use the following command:

:SENS{1-160}:CORR:STAT

Also, once you have calculated the calibration coefficient using the :SENS{1-160}:CORR:COLL:SAVE or :SENS{1-160}:CORR:COLL:SIMP:SAVE command, error correction is automatically turned on.

Using ECal

An ECal (Electronic Calibration) module allows you to perform 1-/2-/3-/4-port calibration and response (THRU) calibration without having to replace the standard device.

ECal works by using the calibration kit data contained in the ECal module instead of the calibration kit data selected for the E5071C. This means that you do not have to define or select a calibration kit when using ECal.

• When two or more ECal modules are connected through the USB port, the system uses the calibration kit data of the first ECal module.

To perform ECal, use one of the following commands:

Simply issuing one of the above commands completes all of the tasks necessary for error correction, including measuring the calibration data, calculating the calibration coefficients, and running the error correction feature.

• Once you have initiated ECal, you cannot cancel the operation.

• No command entered following the initiation of ECal will be processed until ECal completes successfully. Accordingly, if you issue a command that queries some data, the system will not respond to the query until ECal is complete.

The below command was intended to turn ON/OFF the isolation measurement for performing ECal. However, as the isolation performance of ENA is better than ECal, this command no longer works.  ENA ignores this command.

:SENS{1-160}:CORR:COLL:ECAL:ISOL

• This command takes no action and only exists to maintain backward compatibility.

To select the ECal characteristic for a user-characterized ECal, use the following command:

:SENS{1-160}:CORR:COLL:ECAL:UCH

ECal Auto-detect Function

The ECal module can automatically detect which port of the ECal module is connected to the E5071C test port. Turn off the auto-detect function to specify a port manually.

To turn OFF the auto-detect function, use the following command.

:SENS:CORR:COLL:ECAL:ORI

To turn OFF the auto-detect function and set a port manually, use the following command.

:SENS:CORR:COLL:ECAL:PATH

Checking the Applied Calibration Type

When you turn on error correction, you can check the calibration type actually applied to each trace. To check the calibration type, use the following command:

:SENS{1-160}:CORR:TYPE{1-160}?

The above command reads out the same parameter (SOLT3) for both the full 3-port and simplified full 3-port calibrations, and thus they cannot be discriminated. For the same reason, the following calibrations cannot be discriminated: full 4-port and simplified full 4-port, 3-port TRL and simplified 3-port TRL, and 4-port TRL and simplified 4-port TRL.

Defining Calibration kits

Selecting a Calibration Kit

To select a calibration kit, use the following command:

:SENS{1-160}:CORR:COLL:CKIT

Setting the Calibration Kit Name

To set the name of a calibration kit, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:LAB

Standard Definitions

Selecting a Standard Type

To select a standard type, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:STAN{1-30}:TYPE

Setting the Standard Name

To set the standard name, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:STAN{1-30}:LAB

Setting the Standard Value

To set the standard value, use one of the following commands:

As shown in the table below, you need to set different items depending on the standard type.

You need to set the items identified by * marks in the table above.

Saving/Recalling the Definition File

To save the definition of the selected calibration kit to a file, use the following command.

:MMEM:STOR:CKIT{1-20}

To recall the definition of the calibration kit from a file and set, use the following command.

:MMEM:LOAD:CKIT{1-20}

Defining a Subclass of the Standard

To set the standard type that varies with the frequency range, use the following command to specify the subclass.

:SENS{1-160}:CORR:COLL:SUBC

To select the subclass, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:ORD

To set the start frequency of a specified subclass, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:STAN{1-30}:FMIN

To set the stop frequency of a specified subclass, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:STAN{1-30}:FMAX

Defining a Standard Class Assignment

To select the standard to be applied to the OPEN measurement for each port, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:ORD:OPEN

To select the standard to be applied to the SHORT measurement for each port, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:ORD:SHOR

To select the standard to be applied to the LOAD measurement for each port, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:ORD:LOAD

To select the standard to be applied to the THRU measurement between each pair of ports, use the following command:

:SENS{1-160}:CORR:COLL:CKIT:ORD:THRU

To select the standard to be applied to the THRU measurement for the TRL calibration between each pair of ports, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:ORD:TRLT

To select the standard to be applied to the Reflection measurement for the TRL calibration between each pair of ports, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:ORD:TRLR

To select the standard to be applied to the Line/Match measurement for the TRL calibration between each pair of ports, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:ORD:TRLL

Setting the Standard Media Type

To select the media type of the standard to be used, use the following command.

:SENS{1-160}:CORR:COLL:CKIT:STAN{1-30}:CHAR

Saving and loading calibration coefficients

You can save calibration coefficients to a file along with other instrument settings and then later load them from the file.

By default, the system does not save calibration coefficients when it saves instrument settings. Therefore, to save calibration coefficients, you must explicitly configure the system to save them by issuing the following command:

:MMEM:STOR:STYP

To save calibration coefficients to a file, use the following command:

:MMEM:STOR

To load calibration coefficients from a file, use the following command:

:MMEM:LOAD

For more information on how to save and load calibration coefficients, refer to Saving and recalling instrument status

Reading/Writing Calibration Coefficient Alone

The calibration coefficient alone can be read from and written to the E5071C by using the following command:

:SENS{1-160}:CORR:COEF

To write a positive calibration coefficient, use one of the following commands to declare the calibration type:

:SENS{1-160}:CORR:COEF:METH:ERES

:SENS{1-160}:CORR:COEF:METH:OPEN

:SENS{1-160}:CORR:COEF:METH:SHOR

:SENS{1-160}:CORR:COEF:METH:SOLT1

:SENS{1-160}:CORR:COEF:METH:SOLT2

:SENS{1-160}:CORR:COEF:METH:SOLT3

:SENS{1-160}:CORR:COEF:METH:SOLT4

:SENS{1-160}:CORR:COEF:METH:THRU

To validate the written calibration coefficient, use the following command:

:SENS{1-160}:CORR:COEF:SAVE

About Calibration Types and Coefficients

The following table shows the required calibration coefficients for each calibration type.

• If either an invalid calibration coefficient is specified for the writing command or a nonexistent calibration coefficient is specified for its reading command, the following error will occur: 23, Specified error term does not exist

Procedures for Writing Calibration Coefficient

You must follow the steps below to write the calibration coefficient.

1. Declare the calibration type to write.

Execute :SENS{1-160}:CORR:COEF:METH:xxxx command

2. Write any calibration coefficient.

Execute :SENS{1-160}:CORR:COEF command as needed for the written calibration coefficients

3. Validate the calibration coefficients.

Execute :SENS{1-160}:CORR:COEF:SAVE command

• Do not execute any other command while writing the calibration coefficients.This may cause the system to function incorrectly.

• If the fixture simulator is turned on, the calibration coefficient writing will not function correctly. Make sure to turn off the fixture simulator before execution.

Clearing Calibration Data and Calibration Coefficients

Clearing Calibration Data

When the frequency offset function has been disabled

You can use the following command to clear the measurement values of calibration data executed with :SENS{1-160}:CORR:COLL:OPEN command, etc.

:SENS{1-160}:CORR:COLL:CLE

When the frequency offset function has been enabled

You can use the following command to clear the measurement values of calibration data executed with :SENS{1-160}:CORR:OFFS:COLL:OPEN command, etc.

:SENS{1-160}:CORR:OFFS:COLL:CLE

These clear functions make the temporarily settings during the calibration, such as trace number and measurement parameters, recover to the original state.

Clearing Calibration Coefficients

When the frequency offset function has been disabled

You can use the following command to clear the calibration coefficients used.

:SENS{1-160}:CORR:CLE

When the frequency offset function has been enabled

You can use the following command to clear the calibration coefficients used.

:SENS{1-160}:CORR:OFFS:CLE

This command does not clear calibration coefficients related to normal calibration.