Open calibration corrupts S21 measurements using 401 points at 315MHz center with 30MHz span

[jeraymond]

When I do a full calibration at 315MHz center with a 30MHz span using 401 points the S21 measurements is corrupted and looks to be showing noise.

Steps to reproduce:

1. Configure Trace 0 as S11 logmag and Trace 1 as S21 logmag.
2. Set Sweep Points to 401
3. Set Stimulus center to 315M and span to 30M
4. Reset the Calibration
5. Calibrate Open, Short, Load, Isoln, and Thru then tap Done and Save 0.

Expected:

S12 and S21 measurements (e.g logmag) display correct values.

Actual:

S21 measurements look corrupted and show what looks like noise. S12 measurements look normal.

Other Info:

• Firmware version 1.0.79
• I tried some other spans that worked correctly. E.g.) 315MHz center with 100MHz span works. Also 315MHz with 30 MHz span using the default 101 sweep points works.
• The corruption seems to occur when calibrating the Open (with the repro config). When observing S21 logmag trace it changes when calibrating Open in the bug case.

Uncalibrated, notice the blue S21 trace look fairly low noise.

Open calibrated, now the blue S21 trace looks much noisier (corrupt).

Finished the full calibration and attached bandpass filter as a DUT. S12 logmag look correct, but S21 is noise.

Expected S21 output (but uncalibrated).

[metan-ucw]

I can see similar effect but at slightly lower frequency it's centered around 300Mhz. Looks like the 1.0.71 release works fine, but the 1.1 is broken this way.