I have discovered that starting from 2µs/div when one channel from A or B is hidden the other one uses both channels of the ADC to sample the input. But due to calibration problems the signal is worth .
If both channels are enabled the trace looks better
The problem is mainly due to offset and gain difference between the two channels. This can be made visible this way:
- disable one channel
- make an acquisition
- stop the aquisition (the display shows the first view on that post)
- while in hold mode, go to the hidden channel and make it visible.
- you have this
You can see the little offset and the gain difference between the 2 channels.
I tried to do a calibration but I don’t well understand how it works.
For the first column (zero) it is easy. You short circuit the probe and by toggling A navigator you zero the display.
For the second column I suppose it works the same way but I am not sure. And I don’t understand what it is used for.
For the third one as far as I understand it is only a display of the voltage you apply at the input.
When in the third column (or the fifth), when there is a difference between what the Quad and the voltmeter display there is no way to correct the Quad. I thought the calibration was a 2 points calibration (offset and gain) but I don’t understand how to set gain.
On my Quad, on A channel I have a few percent difference between the Quad and the voltmeter so it is of nearly no importance. But on B channel I have between 10 and 15 percent difference between the Quad and the voltmeter. This can explain the problem I have when using the 2 ADC to sample a single channel.