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Create a Balanced Measurement using SCPI

This example program does the following:

creates several Balanced measurements in separate windows
generates markers
calculates statistics
sets limit lines and queries results
queries a measurement to determine if we have a balanced parameter and what type it is.

Note: By their nature, balanced measurements are extremely sensitive to phase differences between the two RF paths that make up the balanced port, especially at higher frequencies. A good calibration (not performed in this example) is critical to achieving good balanced measurement results.

The SCPI commands in this example are sent over a COM interface using the SCPIStringParser object. You do NOT need a GPIB connection to run this example.

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 Balanced.vbs. Learn how to setup and run the macro.

See Other SCPI Example Programs

Dim app

Dim scpi

' Create / Get the VNA application.

Set app = CreateObject("AgilentPNA835x.Application")

Set scpi = app.ScpiStringParser

' A comment

scpi.Parse("SYST:FPRESET")

' This example uses DUT topology Bal-Bal -

' a DUT with a balanced input and balanced output.

' Port mapping for our DUT:

' logical port 1 = physical ports 1 and 4

' logical port 2 = physical ports 2 and 3

' The default is:

' logical port 1 = physical ports 1 and 2

' logical port 2 = physical ports 3 and 4

' logical 1 logical 2

' ___________

' 1 ------| |------ 2 +

' | DUT |

' 4 ------|___________|------ 3 -

' Turn on Four windows

scpi.Parse("DISP:WIND1:STATe ON")

scpi.Parse("DISP:WIND2:STATe ON")

scpi.Parse("DISP:WIND3:STATe ON")

scpi.Parse("DISP:WIND4:STATe ON")

' Create a trace called "sdd21", and for that trace turn on the balanced

' transformation and set the balanced transformation to BBAL SDD21.

scpi.Parse("CALC:PAR:DEF:EXT ""sdd21"",S11")

scpi.Parse("CALC:PAR:SEL ""sdd21""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDD21")

' Feed the sdd21 trace to window 1, trace 1

scpi.Parse("DISP:WIND1:TRAC1:FEED ""sdd21""")

' Similarly create 3 more balanced transmission/conversion parameters

' Create Scd21

scpi.Parse("CALC:PAR:DEF:EXT ""scd21"",S11")

scpi.Parse("CALC:PAR:SEL ""scd21""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCD21")

scpi.Parse("DISP:WIND1:TRAC2:FEED ""scd21""")

' Create Sdc21

scpi.Parse("CALC:PAR:DEF:EXT ""sdc21"",S11")

scpi.Parse("CALC:PAR:SEL ""sdc21""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDC21")

scpi.Parse("DISP:WIND1:TRAC3:FEED ""sdc21""")

' Create Scc21

scpi.Parse("CALC:PAR:DEF:EXT ""scc21"",S11")

scpi.Parse("CALC:PAR:SEL ""scc21""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCC21")

scpi.Parse("DISP:WIND1:TRAC4:FEED ""scc21""")

' Now create logical port 1 reflection parameters, and place them in window 2

scpi.Parse("CALC:PAR:DEF:EXT ""sdd11"",S11")

scpi.Parse("CALC:PAR:SEL ""sdd11""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDD11")

' Feed the sdd11 trace to window 2, trace 1

scpi.Parse("DISP:WIND2:TRAC1:FEED ""sdd11""")

' Similarly create 3 more balanced reflection/conversion parameters

scpi.Parse("CALC:PAR:DEF:EXT ""scd11"",S11")

scpi.Parse("CALC:PAR:SEL ""scd11""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCD11")

scpi.Parse("DISP:WIND2:TRAC2:FEED ""scd11""")

scpi.Parse("CALC:PAR:DEF:EXT ""sdc11"",S11")

scpi.Parse("CALC:PAR:SEL ""sdc11""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDC11")

scpi.Parse("DISP:WIND2:TRAC3:FEED ""sdc11""")

scpi.Parse("CALC:PAR:DEF:EXT ""scc11"",S11")

scpi.Parse("CALC:PAR:SEL ""scc11""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCC11")

scpi.Parse("DISP:WIND2:TRAC4:FEED ""scc11""")

' Now create reverse transmission parameters, and place them in window 3

scpi.Parse("CALC:PAR:DEF:EXT ""sdd12"",S11")

scpi.Parse("CALC:PAR:SEL ""sdd12""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDD12")

' Feed the sdd11 trace to window 3, trace 1

scpi.Parse("DISP:WIND3:TRAC1:FEED ""sdd12""")

' Similarly create 3 more balanced reverse transmission/conversion parameters

scpi.Parse("CALC:PAR:DEF:EXT ""scd12"",S11")

scpi.Parse("CALC:PAR:SEL ""scd12""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCD12")

scpi.Parse("DISP:WIND3:TRAC2:FEED ""scd12""")

scpi.Parse("CALC:PAR:DEF:EXT ""sdc12"",S11")

scpi.Parse("CALC:PAR:SEL ""sdc12""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDC12")

scpi.Parse("DISP:WIND3:TRAC3:FEED ""sdc12""")

scpi.Parse("CALC:PAR:DEF:EXT ""scc12"",S11")

scpi.Parse("CALC:PAR:SEL ""scc12""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCC12")

scpi.Parse("DISP:WIND3:TRAC4:FEED ""scc12""")

' Now create reverse reflection parameters, and place them in window 4

scpi.Parse("CALC:PAR:DEF:EXT ""sdd22"",S11")

scpi.Parse("CALC:PAR:SEL ""sdd22""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDD22")

' Feed the sdd11 trace to window 3, trace 1

scpi.Parse("DISP:WIND4:TRAC1:FEED ""sdd22""")

' Similarly create 3 more balanced reverse reflection parameters

scpi.Parse("CALC:PAR:DEF:EXT ""scd22"",S11")

scpi.Parse("CALC:PAR:SEL ""scd22""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCD22")

scpi.Parse("DISP:WIND4:TRAC2:FEED ""scd22""")

scpi.Parse("CALC:PAR:DEF:EXT ""sdc22"",S11")

scpi.Parse("CALC:PAR:SEL ""sdc22""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SDC22")

scpi.Parse("DISP:WIND4:TRAC3:FEED ""sdc22""")

scpi.Parse("CALC:PAR:DEF:EXT ""scc22"",S11")

scpi.Parse("CALC:PAR:SEL ""scc22""")

scpi.Parse("CALC:FSIM:BAL:PAR:STATe ON")

scpi.Parse("CALC:FSIM:BAL:PAR:BBAL:DEF SCC22")

scpi.Parse("DISP:WIND4:TRAC4:FEED ""scc22""")

scpi.Parse("CALC:FSIM:BAL:DEVice BBALanced")

scpi.Parse("CALC:FSIM:BAL:TOPology:BBAL:PPORts 1,4,2,3")

' Set up stimulus

scpi.Parse("SENS:SWE:POINts 801")

scpi.Parse("SENS:FREQ:STARt 10e6")

scpi.Parse("SENS:FREQ:STOP 1e9")

' Here we demonstrate how to determine if we have

' a balanced parameter and what type it is.

' Read back one parameter to verify its type

scpi.Parse("CALC:PAR:SEL ""sdd21""")

' Is this a balanced parameter?

isbal = scpi.Parse("CALC:FSIM:BAL:PAR?")

' Which topology/device is set?

device = scpi.Parse("CALC:FSIM:BAL:DEV?")

device = Left( device, Len(device)-1 ) ' strip off newline

' Which parameter are we measuring within that topology?

balparam = scpi.Parse("CALC:FSIM:BAL:PAR:" & device & ":DEF?")

balparam = Left( balparam, Len(balparam)-1 ) ' strip off newline

If isbal Then

WScript.Echo "Balanced Parameter: " & balparam & " in topology: " & device & "."

Else

WScript.Echo "Parameter not balanced."

End If