Acoustic Ranging

Pair a phone, then run a synchronized chirp exchange. Both devices record their microphones for 6 s. The laptop chirps at t = 2 s, the phone chirps at t = 4 s. Each chirp is a 200 ms 1→4 kHz linear sweep transmitted at full amplitude — set both devices to maximum volume. The phone uploads its recording over WebRTC and a matched-filter cross-correlation estimates the laptop–phone distance. After the BeepBeep ranging method of Peng et al., SenSys 2007.

Enter the 4-digit code shown on the host laptop to use this phone as the second microphone.

Pair your phone

Code — — — —

Generating session…

On your phone, open sensingstudio.com/acoustic-ranging and enter this code.

Join a session

Enter the 4-digit code from the host laptop:

Run experiment

Ready. 
  t = 0.0 s   both microphones start recording
  t = 2.0 s   laptop emits 200 ms chirp (1 → 4 kHz)
  t = 4.0 s   phone  emits 200 ms chirp (1 → 4 kHz)
  t = 6.0 s   stop · phone uploads recording to laptop

Use a quiet room. Both chirps are emitted at full amplitude — set the laptop and phone volume to maximum. The two recordings are not sample-aligned across devices; the laptop’s clock and the phone’s clock differ. Cross-correlating each recording against the chirp template recovers the two arrival times within each device’s own clock, which is sufficient to estimate the distance.

Result

d₁ · laptop recording — phone chirp time − laptop chirp time, on laptop’s clock
d₂ · phone recording — phone chirp time − laptop chirp time, on phone’s clock
|d₁ − d₂| — round-trip differential
Distance — D = (c / 2) · |d₁ − d₂|, c = 343 m/s

Recordings

Laptop microphone
No recording yet
Phone microphone
No recording yet

Acoustic Ranging · Phone

This phone is the second microphone and a chirp source. Either device can hit Run to start the 6 s exchange. After the BeepBeep ranging method of Peng et al., SenSys 2007.

Status

Tap Start to enable mic and connect.

Keep this page open and the screen on. Place the phone where you want to range from.