
Originally Posted by
Melanie
Measuring an Ultrasonic Receivers signal voltage is a unique approach although I suspect it is not a correct one as I can see many scenarios where this would cause problems.
The correct method is to measure the TIME between the leading edge of a Transmission Pulse and the leading edge of the Received Pulse. Since sound travels at around 331m/Second (with only slight adjustment for altitude and temperature), it comes to pass that you can achieve a resolution of around 0.331mm/uS. With a bit of decent code, a 4MHz PIC should be able to resolve distances as low as 2cm.
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