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utility

Wireless Sensor

Connect up to four phones to a PC as wireless motion sensors for synchronized recording, comparison, impact detection, and FFT analysis.

View on GitHub
Local processing
About your filesFiles and content selected in this tool are processed in your browser and are not uploaded to a Browser Kitty backend.
Operation demo See the basic workflow in a short video.

About this tool

Wireless Sensor turns smartphone motion sensors into a small multi-point measurement setup controlled from a PC or tablet. Up to four phones can be connected at once, with acceleration, acceleration including gravity, rotation rate, and device orientation recorded on a shared synchronized timeline. It is intended for tasks such as comparing vibration at several locations, observing impact propagation, or comparing tilt and rotation between devices.

The connection uses WebRTC DataChannel without signaling, STUN, or TURN servers. Connection metadata is handed directly between the PC and phones using QR codes or copy/paste, and sensor samples travel peer-to-peer between the connected devices rather than being uploaded to a Browser Kitty measurement backend.

Good for

  • Place phones at several points on a desk, floor, or structure and compare when an impact or vibration reaches each location
  • Record vibration from a motor, washer, car, bicycle, or similar source at multiple positions at the same time
  • Compare changes in tilt or rotation from two or more phones on the same time axis
  • Try a classroom or hobby experiment with phones instead of dedicated wireless sensor hardware

What it can do

Key capabilities available in this tool.

How to use

  1. Connect the PC or tablet and the phones to the same Wi-Fi/LAN, then open Wireless Sensor on both sides. Avoid VPNs, guest Wi-Fi, or networks that isolate clients from each other.
  2. Choose the receiver role on the PC and the phone-sensor role on the phone, then follow the guided two-way QR flow. Copy/paste connection codes are available when a camera cannot be used.
  3. After the connection opens, start the sensor on the phone and grant motion-sensor permission. Add more sensors from the receiver and repeat the flow for up to four phones.
  4. Choose an experiment preset or a measurement mode such as motion, vibration, tilt, or rotation. Optionally set sensor names and XYZ positions, impact detection, and the comparison layout.
  5. Start recording and add timestamped markers when useful. After stopping, review timing differences, vibration metrics, FFT results, and other analysis, then save CSV, session JSON, or an HTML report.

Supported

  • The receiver is intended for a PC or tablet, while sensor phones need browser access to DeviceMotionEvent and DeviceOrientationEvent data.
  • Up to four phones can be connected simultaneously. Recorded fields include acceleration, acceleration including gravity, rotation rate, orientation, and browser-reported sensor intervals.
  • Guided presets cover impact propagation, vibration comparison, tilt comparison, rotation comparison, car/bicycle, elevator, washer/motor, and free measurement.
  • Exports include CSV, a reloadable Wireless Sensor session JSON, and a self-contained HTML report with charts and analysis results.
  • An HTTPS-hosted copy is recommended so phone camera and motion-sensor permissions work consistently across modern browsers.

Limitations and notes

  • Same-LAN use is the primary target. Because the app does not use STUN or TURN, connections across different networks or NATs are intentionally out of scope.
  • Company, school, or guest Wi-Fi, VPNs, firewalls, and access-point client isolation can block peer-to-peer traffic even when devices appear to be on the same Wi-Fi.
  • Phone sensor values are not a substitute for calibrated scientific instruments. Accuracy, available axes, and sample rates vary by device, operating system, and browser.
  • Cross-device time alignment is estimated from round trips over WebRTC. Offset and drift are corrected, but PTP- or GNSS-grade synchronization is not guaranteed.
  • Backgrounding or locking a phone can cause the browser to suspend sensor events.
  • Long recordings and multi-phone sessions consume receiver memory. Saving large measurements in segments is safer.
  • Impact detection and FFT results depend on sample rate, thresholds, mounting, and sensor quality.

Frequently asked questions

Are sensor measurements sent to a Browser Kitty server?

No. Connection metadata is exchanged directly by QR code or copy/paste, and measurements are sent to the connected peer over WebRTC DataChannel. The app also uses no signaling, STUN, or TURN server.

Do the PC and phones need to be on the same Wi-Fi?

The intended setup is the same local network. Even on the same Wi-Fi, guest networks or client isolation can block the connection, and VPN or firewall settings can also prevent peer-to-peer traffic.

How many phones can be measured at the same time?

Version 1.0.0 supports up to four phones at once. Each phone uses an independent WebRTC peer connection, so one disconnected sensor does not stop the others.

Can it accurately measure impact propagation speed?

With sensor positions entered, it can calculate straight-line distance and an apparent propagation speed, but browser sampling intervals, device sensor differences, mounting, and synchronization uncertainty affect the result. It is suited to comparison and exploratory experiments rather than precision instrumentation.

Can I reopen a measurement later?

Yes. Save a Wireless Sensor session JSON to reload the measurement later without reconnecting the phones and rebuild the analysis and report. CSV and self-contained HTML report exports are also available.

Offline version and source code

The app is a self-contained single HTML with its QR generation and decoding libraries embedded and no runtime CDN or measurement backend. A disconnected copy can be used, but some browsers restrict camera or motion-sensor permissions on file://, so the HTTPS-hosted version is usually more practical.

View source on GitHub

Use together

Useful next steps and companion tools, organized around the workflow.

Check sensor support first Device Check Use Device Check first when you want to confirm that the phone and browser expose the required motion-sensor APIs. Check tilt on one phone Pocket Level Use Pocket Level when you only need a single phone as a bubble level rather than synchronized multi-device measurement.