How a PC can tell how far away a device is
Most Bluetooth gadgets announce themselves several times a second so phones and computers can find them. Those announcements carry a name, sometimes a maker code, and arrive at a measurable strength.
Signal strength falls off with distance in a predictable way, so a strong signal means a device is close and a weak one means it is further off. Walls, bodies and furniture soften the signal, which is why the app lets you say what kind of space you are in.
It is an estimate, not a tape measure. It is very good at telling you which of two devices is nearer, and whether you are getting warmer as you walk. Bluetooth carries no direction, so to find a lost device, turn slowly on the spot and walk the way the reading improves.
How to find a Bluetooth device with your PC
Bluetooth Device Scanner lists every device advertising near you with a signal meter and an estimated distance. To track down one in particular, use Find it and follow the reading.
- Set the kind of space you are in, open space, an ordinary room or walls in between, so the distances fit it.
- Find the device in the list, open it, and press Find it.
- Carry the PC and watch the large distance readout, which refreshes four times a second with the last minute of signal drawn beneath.
- Walk the way it says warmer, and turn on the ticking to sweep the room without looking at the screen.
- If it holds steady, turn slowly on the spot; your body blocks the signal, so walk toward the direction where it peaks.
What a Bluetooth scanner can tell you about each device
Open any device for its details: the maker, named from the company code it broadcasts for sixty makers, the signal in dBm, its transmit power and the services it offers. Thirty-two services are spelled out in words, such as Heart Rate, Battery, Keyboard or Mouse, and Eddystone Beacon.
Apple devices are told apart from what they broadcast, so you see AirPods or Beats, Watch is nearby, Apple TV or HomePod, or Find My tag rather than a bare address. Devices Windows is already paired with are listed too, marked as paired or connected.
Reading the list: rotating addresses and devices that go quiet
Nearly every phone and tracker advertises a randomized address that changes every quarter of an hour. That is deliberate, and it is why one phone can appear as several rows over an evening. A name you give a device is kept against its address for as long as that address lasts.
Devices advertise in bursts, so one that goes silent for a minute has usually not left. Instead of vanishing from under the pointer, it moves to a Gone quiet section below the list, folded away until you open it.
Scanning for AirTags, Tiles and Chipolos
Trackers are recognized from what they broadcast and called out the first time each one is heard. Close the message and it stays closed until a tracker you have not seen before appears, which raises it again.
The scanner only listens. It never pairs or connects, changes nothing on your PC or anyone else's device, and nothing leaves the PC unless you save the list yourself as CSV or JSON.
