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Holding the S-parameter test set switching.

Question asked by drkirkby on Dec 15, 2013
Latest reply on Dec 18, 2013 by ghvgjvh
I was hunting in the 8720D manual today and stumbled across the GPIB commands CSWION and CSWIOFF. There is not much information on them, but I also have an 8720ES manual, which is more informative. I'm trying to understand what these commands are doing and how it might (or might not), relate to something I asked the other day.  Any way to stop 8720D measuring S12 & S22 after a 2-port calibration?

What follows is taken from the 8720ES manual, although I only have the older D model with the latest firmware. (I find the ES manuals are often more accurate than the D ones for my firmware). 

Select test set continuous switching. When continuous switching is on, the analyzer measures all four S-parameters each time before displaying the data for a full 2-port cal measurement. 

Select test set hold mode. The analyzer measure all four S-parameters once then measures the desired parameter continuously. This is knows as a fact 2-port cal measurement and is less accurate than a full 2-port calibrated measurement. 

*CSWI* (this is not even documented in the 8720D manual, but works on my 8720D)
Queries whether continuous switch is on or off. (This returns 1 if continuous, or 0 if held).

Sets number of sweeps for test set switching (range 0-999; 0 is hold, 1 is continuous, 2-999 = number of sweeps)

One can also access these from the CAL menu. 

*TEST SW CONTINUOUS* toggles the internal solid state switch from a hold mode, to a continuously switching mode, or to a number of sweeps mode when full 2-port correction is enabled. Use for fast 2-port calibration (ES only)

I'm trying to understand exactly what this is doing. I seem to be able to stop the lights on the front panel of the VNA from switching, but if I put 2 channels on, both S11 and S22 can be displayed, and both get updated, despite the fact it seems the S-parameter test set is not switching. What is happening, and what are these commands intended for? Googling CSWIOFF I found this thread  Full 2-port calibration with HP 8753E Network Analyzer  
with some comments from Joel about  being intended for filter tuning. 


Edited by: drkirkby on Dec 15, 2013 12:53 PM