DXing FM Bluetooth Transmitters


Paul Blundell
 

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?


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.

73,
kevin
kc6pob

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?


Paul Blundell
 

Thanks for the reply.

My idea was to hunt down the FM side of this, where it transmits the signal from the phone to a free frequency on the FM band.

On Wed, May 26, 2021 at 3:33 PM kevin asato <kc6pob@...> wrote:
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.

73,
kevin
kc6pob

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?



--
Paul


Marc Coevoet
 

Op 26/05/2021 om 02:28 schreef Paul Blundell:
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?
I have this item, it connects to your computer and can take over audio via usb, so it is digital audio as input. (xubuntu linux).

Without adding a wire as antenna, you will only reach 10 meters, but ... a simple 75cm wire will make reception possible in (my car) radio for about 500m. Of course, I choose a good empty frequency ...

It can make such a strong tx, that you need to think about neighbours!
Some stations close to the tx freq, will get bad reception ...

Marc

--
The "Penguin" has arrived - and he's not going away - ever.
For former Apple users: Xubuntu.org (menu's up left)
For former Windows users: Lubuntu.org (menu's down left)