Perform Unknown Thru or TRL Cal

The following program performs either a 2-port SOLT Unknown Thru Cal or a 2-port TRL Cal. The 85052C Cal Kit used in this program contains both types of standards. This program can be run on 2-port or 4-port VNAs. When run on select PNA-L models, a Delta Match Cal is required.

This VBScript (*.vbs) program can be run as a macro in the VNA. To do this, copy the following code into a text editor file such as Notepad and save it on the VNA hard drive as Unknown.vbs. Learn how to setup and run the macro.

Sub PerformUnknownThruOrTRLCal()

Set pna = CreateObject("AgilentPNA835x.Application")

Set scpi = pna.ScpiStringParser

' Specify connectors for Ports 1 and 2

scpi.Parse "SENS:CORR:COLL:GUID:CONN:PORT1 'APC 3.5 female'"

scpi.Parse "SENS:CORR:COLL:GUID:CONN:PORT2 'APC 3.5 male'"

'If your VNA has 3 or 4 ports, uncomment one or both of

'these next two lines, to explicitly specify this is a 2-port cal.

'scpi.Parse "SENS:CORR:COLL:GUID:CONN:PORT3 'Not used'"

'scpi.Parse "SENS:CORR:COLL:GUID:CONN:PORT4 'Not used'"

' Specify cal kit for Ports 1 and 2

scpi.Parse "SENS:CORR:COLL:GUID:CKIT:PORT1 '85052C'"

scpi.Parse "SENS:CORR:COLL:GUID:CKIT:PORT2 '85052C'"

' Since the 85052C cal kit contains SOLT standards and also TRL

' standards, these next two lines set cal and thru method.

' Always send the init command before and after these two commands

scpi.Parse "SENS:CORR:COLL:GUID:INIT"

scpi.Parse "SENS:CORR:COLL:GUID:PATH:CMEThod 1,2,"SOLT"

scpi.Parse "SENS:CORR:COLL:GUID:PATH:TMEThod 1,2,"Undefined Thru"

' To set up the cal as TRL, comment the previous 'CMET' line and uncomment

' this next line. The TMEThod is set by default

'scpi.Parse "SENS:CORR:COLL:GUID:PATH:CMEThod 1,2,"TRL"

' Initiate the calibration

scpi.Parse "SENS:CORR:COLL:GUID:INIT"

' Query the list of ports that need delta match

retStr = scpi.Parse("SENS:CORR:COLL:GUID:DMAT:APPL:PORT?")

portList = Split(retStr, ",")

' If portList contains just one element and it's value is 0, then that indicates

' none of the ports being calibrated require delta match data.

' Note: if each testport on the VNA has it's own reference receiver (R channel),

' then delta match is never needed, so portList will always be just 0.

lowerBound = LBound(portList)
If (UBound(portList) <> lowerBound) Or (CInt( portList(lowerBound) ) <> 0) Then

' Delta match data is required for at least one port.

' For this example, we assume a Global Delta Match Cal has previously been

' performed so the Global Delta Match CalSet exists.

' The Global Delta Match CalSet is used when the APPL command is invoked

' without a specific calset ID (GUID).

scpi.Parse "SENS:CORR:COLL:GUID:DMAT:APPL"

End If

' Query the number of calibration steps

retStr = scpi.Parse("SENS:CORR:COLL:GUID:STEP?")

numSteps = CInt(retStr)

' Measure the cal standards

For i = 1 To numSteps

prompt = scpi.Parse("SENS:CORR:COLL:GUID:DESC? " & CStr(i))

retVal = MsgBox(prompt, vbOKCancel)

If retVal = vbCancel Then Exit Sub

retStr = scpi.Parse("SENS:CORR:COLL:GUID:ACQ STAN" & CStr(i) & ";*OPC?")

' Compute the error coefficients and save the cal to CalSet, and turn it on

scpi.Parse "SENS:CORR:COLL:GUID:SAVE"

MsgBox "Cal is done!"

End Sub