HC Sr04 Ultrasonic Sensor Unstability Issue

The Values fluctuate in between. Could anyone explain why and how to get rid of them?

For a 8.5mm wavelength (approx) and a 4us timer granularity, those results look pretty good to me.

Are there any better options with minimal error ?

rajesh249: Are there any better options with minimal error ?

Build a stable oscillator at say 10 MHz. Use counter integrated circuits to count how many pulses of the oscillator there are in the duration of the pulse from the ultrasonic sensor; interface the outputs of the counter to your Arduino.

Hi, Use a laser type distance measuring device, try SICK or IFM. google.

Tom.... :)