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How to transfer user-defined equations, like e.g Sdd11= (S11-S21-S12+S22)/2

Question asked by stephangiesinger on Feb 22, 2013
Latest reply on Feb 26, 2013 by takeshio
Hello community, 

I want to make measurements with mixed mode S-parameters using the ENA 5071 C. Therefore I enabled the balance-unbalance conversion within the Fixture Simulator.
The display now shows the desired mixed mode parameters, Sdd11, Sdd112...Scc22. 
But how do I transfer the actual displayed trace curve to MS Excel (via LAN) ? 
*I am using Agilent VEE and MS Excel/VBA, but sending the command 'instrument.WriteString ":CALC1:PAR1:DEF Scd12" ' to the ENA, results in an error as this command is just specified for Sij with i and j = 1..4.* 

So how do I select the desired mixed-mode S-parameter and how to read it ?


I tried a few things but just got more puzzled... 

instrument.WriteString ":CALC1:PAR1:SEL"
instrument.WriteString ":CALC1:TRAC1:EQU:STATE ON"
instrument.WriteString ":CALC1:TRAC1:EQU:TEXT 'Sdd_test=S21/(1-S11)'"
instrument.WriteString ":CALC1:TRAC1:EQU:TEXT?"
equ_string = instrument.ReadString()
MsgBox equ_string
--> Defining my own equation works, in the upper left corner the notation of the trace changes to "Tr1 Sdd_test Log Mag 10.000db/ Ref 0.000db [Equ]", 
Command MsgBox equ_string gives 'Sdd_test=S21/(1-S11)' as expected. 
Apparently the Mixed-Mode S-parameters are NOT defined as equations ?!??! At least all definitions in the right column remain unchanged (Sdd11, Sdd12....). 

instrument.WriteString ":CALC1:PAR1:TNAM:DATA tracename"
instrument.WriteString ":CALC1:PAR:TNAM:DEF? tracename"
equ_string = instrument.ReadString()
MsgBox equ_string

--> Trace 1 at channel 1 (which in my experiments I always assume to be the active trace) is assigned the name 'tracename'. MsgBox equ_string shows the correct assigment, returning 'tracename' as result. 
But on the display of the ENA the annotation 'tracename' doesn't appear anywhere. Is this correct ? It still says "Tr1 Sdd_test Log Mag 10.000db/ Ref 0.000db [Equ]" instead of "tracename sdd_test Log Mag 10.000db/ Ref 0.000db [Equ]" as I expected. 

instrument.WriteString ":CALC1:PAR1:TNAM:DATA?"
equ_string = instrument.ReadString()
MsgBox equ_string

--> The most surprising result: equ_string now contains "S11". But why ??? Why doesn't it contain "Sdd_test" as all previous operations concerned the same Trace 1, Channel 1. Furthermore the ENA is operated in balanced mode, so I would have expected at least Sdd11. But where the hell does S11 come from ?

Edited by: Stephan Giesinger on Feb 26, 2013 2:00 AM