Issue with Circuit analyser?

Hi, I recently got a PCSU1000 to complement my PCGU1000. Very happy with the intstrument but I ran into an issue with the Circuit Analyser.

Running this on a Win10-64bit PC and software version 4.07.

If I make the following settings:
PCGU output at sine, 0.10Vrms = -20dB output signal level.

PCSU1000 at 50mV input range, both channels.

Output a of PCGU1000 to input 1 of PCSU1000 via coaxial cable.
Output 2 of PCGU1000 to input 2 of PCSU1000 via coaxial cable.

When I run a bode plot without the option ‘Options -> Normalise output by input’, I get the following results:

Hz mVrms dBV deg
1000 100.812 -19.930 -0.1
2000 100.952 -19.918 -0.2
3000 100.915 -19.921 -0.3
4000 100.681 -19.941 -0.2
5000 100.826 -19.929 -0.1
6000 100.825 -19.929 -0.3
7000 101.196 -19.897 -0.4
8000 101.457 -19.874 -0.3
9000 101.465 -19.874 -0.5
10000 101.625 -19.860 -0.3

etc…

The measured output is at approx. -20dB, as expected.

Now, When I run a bode plot with the option ‘Options -> Normalise output by input’ enabled, I get:

Hz mVrms dBV deg
1000 0.100 -80.004 -0.1
2000 0.100 -79.998 -0.2
3000 0.100 -80.004 -0.2
4000 0.100 -79.998 -0.3
5000 0.100 -80.002 -0.3
6000 0.100 -80.003 -0.3
7000 0.100 -79.997 -0.4
8000 0.100 -79.993 -0.3
9000 0.100 -79.992 -0.5
10000 0.100 -79.995 -0.3

etc…

From what I expected, the -20dB output signal should be normalised by the -20dB input signal, resulting in -20dB(out) - (-20dB(in)) = 0dB transfer from my coaxial cable.

So why am I seeing -80dB? Are my expectations incorrect or am I missing something???

Thank you for reporting this issue.
I’m sorry for the inconvenience.

Indeed, the problem seems to occur only if option “Normalize Output by Input” is selected and CH2 Volts/Div setting is 50mV/div or lower.
As a workaround you can use 0.1V/div setting on CH2.
In “Normalize Output by Input” mode the CH2 is only used to monitor the generator output voltage.
The accuracy on 0.1V/div range is good enough for this purpose. On CH1 you can use all Volts/Div ranges.