Thank you all for giving your thoughts!
But there’s 2 separate things I’m trying to do. First exploring the method of using a ramp, this cannot be done by using dc steps
.
Secondly hunt down any problem that is in the way of getting the most precise results.
As a reference I created a dataset using dc steps and measure the outcome values with a MM. This will be the most precise, but also “more work”. If I had a SCPI MM, I would have used it to do automatic measurements. But I don’t, hence exploring the other method.
There seems to be nothing wrong with the method either. It shows great stuff, like that calculating values the way the documentation says is wrong.
But it also shows another structural problem. My awg has a unexpected jumps (2 mV) in the ramp that seems to have a digital cause. Probably in the DC stepping as well, but it would not have been noticed that way.
That problem cannot be blamed on the method. The method still gives excellent results, but when calculating slopes over small distances it shows that error. This is also because the jump does not restore it self. (It’s not a hill, but a higher plane.)
Maybe I have not been clear (writing these things down is sometimes a real struggle). But I won’t agree on the matter that there’s nothing wrong with AWG, and just use another approach that masks that problem.
For the device to get trustworthy, I now need to know what is happening. If it is a dac error this size, it will add something strange (high freq content) to every signal it generates! Or maybe the ramp is not “calculated” in a correct way in the firmware. That I would prefer, because a firmware update might correct it.
So my guess is that the problem is not understood. If it is, there’s a difference in opinion. But that’s ok too.