Re: DXing FM Bluetooth Transmitters

kevin asato

Your classic Bluetooth devices (not Bluetooth Low Energy (LE)) are rated at 10meters or less (Class 3). i also have a Bluetooth device that is Class 1 which has a ranged of 100 meters or so (RS-232 serial port extended). Distances on Class 4 and 5 devices are supposed to work at higher speeds but these are primarily data devices versus Class 1 and 2 which are primarily cameras, computers, and audio devices. Bluetooth has the ability to peer to many other devices but smaller devices will peer only to another device as this is a horsepower/resource issue and will also serve as a barrier to intrusion but limiting available connections.

i have not tried to DX/DF Bluetooth devices but have gotten into Bluetooth devices that were not password protected or left to the default passcode. This generally happens in a hotel or airport where there are lots of people using Bluetooth and are rather sloppy at personal protection. Not into snooping so i did not get past the front door to look at peoples content. 

in the same wireless spectrum with Bluetooth is Wifi in the 2.4GHz band allocation. In the early days of WiFi there was a thing called War Driving/War Chalking were people made it a sport to look for open Access Points to gain network access. There devices have a bit more energy being radiated with range up to 1000 feet in clear space. Around my neighborhood in the City, i typically see about 20 or more access points as my neighbors and i have multiple APs to cover the blind spots in our homes (this despite all the advertising claims). i would probably see more if the table of learned devices was not saturated. You can also DF (Direction Find) the location of an Access Point or WiFi device by using Yagi antennas; just not the Cantenna as they are never the right tool for this frequency band.


On Tue, May 25, 2021 at 5:28 PM Paul Blundell <tanger32au@...> wrote:
Of late I have been looking for some new targets, has anybody tried or thought of hunting down the small FM transmitters that are used to connect a Bluetooth phone to the car radio?

If so, what sort of range would you expect?

Join to automatically receive all group messages.