[time-nuts] T.I. experimenting - newbie question

[Hal Murray]

> Here are the results I got using your suggestion. The numbers may be a bit
> different than last night as I'm not sure I'm using the same cable.

> A+, B+ = 18.9 ns
> A-, B- = 19.4 ns
> Obviously there is some difference in delay between the A and B channels.
> Otherwise, the two numbers would have been identical - correct?
...
> If I take the average of the two readings, I get 19.05 ns, which is more
> precise than the readings I'm taking. I'm rounding to the nearest 0.1 ns on
> the readings. 

There are several possibilities for asymmetry.
  The input signal could have other than a 50/50 high/low ratio.
  The trigger levels could be set at other than the half-way point.

Do you have a scope?

There are probably second order problems with different rise/fall times.


> A+, B- = 5014.6 ns
> A-, B+ = 5023.5 ns
> If I take the average of these two readings and subtract out the 5 us for
> 1/2 period of the 100 KHz square wave, if get 19.15 ns. This agrees
> very closely with the above average.

I read that as everything mostly works.

The question is how well does it work and/or what can you do to get 
more/better data?

You can get another set of numbers by swapping the A and B inputs so the 
signal goes from B to A rather than A to B.

Some of the errors might be more obvious if you deliberately offset the 
trigger levels.

NB:  That's for all 4 modes:
  A+ to B+ will be slightly less than a whole cycle.
  A+ to B- will be slightly less than a 1/2 cycle.
...




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