Active acoustic radar

Sonar Pulse

Your speaker chirps near-ultrasound, your mic listens for the echoes, and the room's surfaces are mapped from the time the sound takes to come back.

standby

--mNearest

--msRound trip

--Echoes

Headphones off. Best with device speaker and mic in a quiet room.

Transmit

A 5 ms linear sweep from 18 to 20 kHz fires from your speaker every second - high enough to be near-inaudible.

The mic captures the room. Each surface bounces the chirp back at a delay set by how far away it sits.

Cross-correlating the recording with the original chirp finds those delays, and time becomes distance.

CHIRP18-20 kHz sweepPULSE5 msINTERVAL1 sRANGE6 mMETHODcross-correlation