> litres). So - 1mm of oil level in tank corresponds to 1 litre.
>
> What is the maximum precision you can squeeze out from ultrasonic ping
> measurement? Should be well under 1mm?!

Max resolution at 4MHz clock would be 1us, if all the rest of the circuit
is up to the job.  In 1us, sound travelling at 330m/s would travel 0.33mm.
My display is at 1 litre resolution, but accuracy is probably much lower.
Each time I take a number of readings and display the average.

I haven't studied absolute accuracy etc.  This was never meant to be a
commercial design, it was really a very quick project to replace a broken
mechanical gauge, and it worked 'good enough' straight off.  At the moment,
it just streams out TTL serial for display on an LCD inside.

Nigel


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