Bluetooth Tracking Device

Bluetooth direction finder points out the transmitting module.

Jeremy Cook
1 year ago

As short range transceivers, Bluetooth devices are typically kept close at-hand. However, you may run into a situation where you need to find an errant Bluetooth device that is frustratingly on, but not seen, or maybe you just want to show that you can point out every little transmitting doodad in your house. Whatever your directional Bluetooth need, this DIY tracker shows whether you’re “hot” or “cold,” when attempting to point at a device.

The build consists of a length of PVC pipe, with a coil of wire spaced at 27.6mm per turn wrapped around its diameter. The base of the tube attaches to a copper plate.

The coil is soldered to the core of a coaxial U.FL cable, and the shield is soldered to the base, which in turn is connected to an ESP32 module (which works with a second ESP32 in this particular case). With a bit of code to display the relative signal strength on the rig’s screen, it acts an effective Bluetooth direction finder, demonstrated via the clip below.

The coil is designed to pick up a frequency of 2440 MHz, roughly in the center of the 2400 to 2483 MHz Bluetooth transmission range. The device's beam angle is set up at 30 degrees.

While you may or may not need such a device to find your lost earbuds and the like, it’s a fascinating concept that could potentially be adapted to other radio-finding duties. Besides describing this particular project, the writeup gives links to resources for constructing your own, whether to pinpoint an unknown signal, or to extend a device's transmission range!

Jeremy Cook
Engineer, maker of random contraptions, love learning about tech. Write for various publications, including Hackster!
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