0000000000000001 repeated 15 times

0000000000000010 repeated 15 times

0000000000000011 repeated 15 times

That is a "mini-triangle" containing 3 discrete analog levels, something like this:

oooooooo____ooooooooooooo____ooooooooo

oooo____|oooo|____oooo____|oooo|____oooo

____|oooooooooooo|____|oooooooooooo|____

Don't look at the o's, just the bars to imagine the waveform.

45 samples make up about 980 Hz. One step is about 43 uV. I suppose this needs to be further amplified (probably with a simple op-amp gain stage) to be viewable on an oscilloscope. This track will check the 2nd digit. The second step should be exactly between the first and third step.

The second track contains:

0000000000000011 repeated 15 times

0000000000000100 repeated 15 times

0000000000000101 repeated 15 times

That is the 3rd digit is checked for linearity.

With 15 tracks one could check all the bits from LSB+1 to MSB.

What do you think about this idea?