Can someone help (Bluetooth technical question)?

Loopthrough

Member
I'd like to know something I can't get a definitive answer for. Can anyone help?

Is Bluetooth always transmitting, even if it has never had a device paired with it?

For example in a TV (or devices) with no Bluetooth on/off option, just an 'add device' menu.
 

EndlessWaves

Distinguished Member
I'd expect any wireless device to only transmit when it's actively transferring data, putting out a constant radio signal would be rather disruptive.

If you're asking whether it'll make any transmissions then...

As far as I'm aware In the absence of other devices bluetooth only transmits when it's specifically looking for other devices to pair with - in the case of this example when you open the add device menu.

However, if the device is currently discoverable then it will monitor for connection inquiries from other bluetooth devices and transmit an appropriate response.
 

noiseboy72

Distinguished Member
Many TVs have the ability to automatically connect to matching peripherals, so they will periodically ping to let such devices know they are there.

Current Bluetooth is a combination of "simple" Bluetooth for basic communication and something more akin to wifi to transfer larger amounts of data. This higher power, wider bandwidth signal is only switched on when required and regular Bluetooth is much lower power.

If you have a car with keyless entry, the field strength is likely to be higher than conventional Bluetooth.
 

Loopthrough

Member
Thanks for the replies, but I'm still not clear.
I don't know all the right terms. Hope someone can help me out/correct me here.

Let's say a BT device is the TV. The TV doesn't have a BT on/off button, so BT must be on and active/transmitting/scanning all the time (using BLE), even when not paired, right?

Even if you can't "see" the TV when you scan for nearby BT devices (because the TV's not in pairing/discovery mode)?

If the TV is not connected to any device but could be connected to a BT keyboard or speaker/heaphones, it's always the "master" device. The accessory becomes the "slave" device once paired.

Does this mean the TV is always be scanning and transmitting signals to check for nearby devices even if the user never connects/pairs anything with it?

Only TVs/devices with a clear BT on/off button (like Android TV) have the ability to disable the BT antenna, yes?

A bit like how a smart meter is in constant "ping" contact with the cell tower and the in-house display.
 

EndlessWaves

Distinguished Member
I don't know all the right terms. Hope someone can help me out/correct me here

...

so BT must be on and active/transmitting/scanning all the time (using BLE), even when not paired, right?

Using lots of terms doesn't really clarify anything because they mean different things.

Are you asking from a interference perspective and wish to know when the bluetooth radio is contributing to the electromagentic radioation of the set?

Are you concerned about data security and want to know if the TV is vulnerable to being hacked if an exploit is discovered?

Is it something else?
 

Loopthrough

Member
Using lots of terms doesn't really clarify anything because they mean different things.

Are you asking from a interference perspective and wish to know when the bluetooth radio is contributing to the electromagentic radioation of the set?

Are you concerned about data security and want to know if the TV is vulnerable to being hacked if an exploit is discovered?

Is it something else?
I'm learning the technical terms!
Security and (tin foil hat) concerns.

I just want to know, will TVs (and other "master" devices like radios) with BT (and no BT on/off setting, just a Pairing menu) be transmitting and/or receiving even if no device is paired?

Or do they go into some kind of auto antenna off mode until the first device is Paired?
 

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