Calculation
r = c·t / 2
Sound travels to the obstacle and back within the measured time, so the distance sought is only half the total path length.
Laufzeitprinzip s = c·t nach Dubbel Meßtechnik W 2.3.1 (Impuls-/Echoverfahren), hier Hin- und Rückweg: r = c·t/2
Distance measurement from sound travel time (echo principle)
Sound travels to the obstacle and back within the measured time, so the distance sought is only half the total path length.
MINTSI
02
Result
Select a target and calculate.
Understand the inputs
- Distance r — Distance between the source/receiver and the reflecting surface.
- Speed of sound c — Propagation speed of sound in the medium involved.
- Measured travel time t — Time between sending the signal and receiving the echo (round trip).
Example
c=343 m/s and t=0.1 s (100 ms) give r=343·0.1/2=17.15 m.
Assumptions and limits
Point-like, stationary source and stationary target, a straight propagation path and constant speed of sound; multiple reflections and timing errors are excluded.
Understand Distance measurement from sound travel time (echo principle)
This calculator determines the distance to a reflecting surface from measured echo travel time, the basic principle behind echo sounding, ultrasonic sensors and time-of-flight distance meters.
What does this quantity describe?
The signal travels to the obstacle and back within measured time t. Since the distance sought is only the one-way path, r=c·t/2.
Formula and variables
r = c·t / 2
r = c·t/2
| Symbol / input | Meaning |
|---|---|
| Distance r | Distance between the source/receiver and the reflecting surface. |
| Speed of sound c | Propagation speed of sound in the medium involved. |
| Measured travel time t | Time between sending the signal and receiving the echo (round trip). |
Choose the inputs correctly
c is the speed of sound in the medium involved, t the measured time between sending the signal and receiving the echo.
How to use the calculator
Derive c from medium temperature (see the speed-of-sound-in-air calculator) or take it from reference tables for water or another medium; take t directly from the measuring device.
Worked example
c=343 m/s and t=0.1 s (100 ms) give r=343·0.1/2=17.15 m.
Understand the result and units
An incorrectly assumed speed of sound (e.g. air instead of water) produces a proportionally wrong distance value.
c is a speed, t a time. r is output as a length.
Typical applications
Ultrasonic distance sensors, echo sounding in shipping and fishing technology, and time-of-flight distance meters.
Assumptions, limits and common mistakes
Point-like, stationary source and stationary target along a straight, undisturbed propagation path, and constant speed of sound throughout the medium; multiple reflections, refraction at medium boundaries and instrument timing delays are excluded.
Common mistake: Do not forget to divide by 2; the measured time covers the signal's round trip.
Frequently asked questions
What is “Distance measurement from sound travel time (echo principle)” used for?
Ultrasonic distance sensors, echo sounding in shipping and fishing technology, and time-of-flight distance meters.
Where do the input values come from?
c is the speed of sound in the medium involved, t the measured time between sending the signal and receiving the echo.
What does the result not cover?
Point-like, stationary source and stationary target along a straight, undisturbed propagation path, and constant speed of sound throughout the medium; multiple reflections, refraction at medium boundaries and instrument timing delays are excluded.