A mobile TDOA calculator that finds the exact origin of knocks, clicks and vibrations on any component — using accelerometers and an oscilloscope.
Works offlineInstallable on Android & iOSNo data sent anywhere
What each tab does
Calculate
Single pair A–B or A–C. Linear result bar.
4-Sensor
Two pairs, proportional rectangle map.
3-Sensor
Triangle mode, TDOA hyperbola solver.
Materials
37 materials. Tap to auto-fill calibration.
Help
8-step animated tutorial covering all modes, sensor placement, calibration and signal tips.
How it works
1
Calibrate — find the speed of sound
Strike the component outside the sensor pair. Enter the sensor spacing (cm) and the measured time delay (µs) — the app calculates the speed of sound in the material.
2
Measure — capture the target event
Cause the actual knock. Read the time delay Δt from the oscilloscope and note which sensor triggered first. Enter both values.
3
Locate — read the result
The app calculates the distance from each sensor to the source and displays it on a scaled visual map.
What you need: two or more accelerometers, an oscilloscope capable of measuring time delays in the microsecond range, and a tape measure.
NVH Source Locator
TDOA Accelerometer Calculator
Calculate
4-Sensor
3-Sensor
Materials
Help
Pair A – B
Pair A – C
Step 1 Calibration — Speed of Sound
Sensor spacing A–B
cm
External knock time delay
µs
Calculated speed of sound
— m/s
Step 2 Event Measurement
Event time delay
µs
Which sensor heard it first?
Step 1 Calibration — Speed of Sound
Sensor spacing A–C
cm
External knock time delay
µs
Calculated speed of sound
— m/s
Step 2 Event Measurement
Event time delay
µs
Which sensor heard it first?
Step 3 Result
From A
—
cm
From B
—
cm
Source is closer to
—
Place four sensors around the area. A–B = horizontal pair (left/right sides), C–D = vertical pair (top/bottom sides). The rectangle scales to your actual spacing ratio.
Pair A–B Left / Right sides
A–B spacing (cm)
cm
Calib. time delay (µs)
µs
Event time delay (µs)
µs
First sensor
Pair C–D Top / Bottom sides
C–D spacing (cm)
cm
Calib. time delay (µs)
µs
Event time delay (µs)
µs
First sensor
Result 2D Source Position
From A (left)
—
cm
From C (top)
—
cm
A=left · B=right · C=top · D=bottom (midpoints of each side)
Place sensors A, B, C at the three corners of a triangle. Measure all three side lengths. Calibrate and measure pairs A–B and A–C. The app solves TDOA hyperbola intersection to locate the source.
Setup Triangle side lengths
A–B side length (cm)
cm
A–C side length (cm)
cm
B–C side length (cm)
cm
Pair A–B Calibration & measurement
Calib. time delay (µs) — knock outside A–B
µs
Event time delay (µs)
µs
Which sensor heard it first?
Pair A–C Calibration & measurement
Calib. time delay (µs) — knock outside A–C
µs
Event time delay (µs)
µs
Which sensor heard it first?
Result Triangulated Position
From A
—
cm
From B
—
cm
From C
—
cm
Fit quality
—
residual
A, B, C = sensor corners · dot = estimated source
Typical longitudinal wave speeds at room temperature. Tap a material to use its speed in Step 1. Always calibrate in-situ for best accuracy.
Add to Home ScreenInstall NVH Locator for quick access — works offline too.
Add to Home Screen
Tap the Share button (↑) in Safari, then choose “Add to Home Screen”.