E60, E61, E63, E64, E87, E90: Bluetooth Radio Standard
The following information is given:
- Bluetooth radio standard
- Number of possible bluetooth mobile phones
- Deactivating bluetooth connection
- Transmission frequency
- Call-monitoring security
Bluetooth is a new short-range radio standard with which several units with bluetooth interface are able to communicate with each other at once. Bluetooth allows up to 8 bluetooth-compatible transmission/reception devices within a radius of up to 10 meters to be networked together.
4 bluetooth mobile phones can be paired to the TCU control unit. However, only one of the paired bluetooth mobile phones can be used for communication. If there is more than one bluetooth mobile phone in the reception area of the ULF: The bluetooth mobile phone at the top of the list has top priority for establishing a connection.
If 4 bluetooth mobile phones are already signed on to the ULF: The next time a new mobile phone is signed on, the mobile phone that was signed on to the list first will be deleted.
The bluetooth connection in the vehicle can be temporarily deactivated. This may be necessary in the following situations:
- If bluetooth is not approved for use in the country concerned.
- If a call is to made or continued in privacy mode, i.e. only using the mobile phone.
Transmission frequency
Bluetooth uses the licence-free, global ISM frequency band at 2.45 GHz. The frequency range from 2.402 GHz to 2.480 GHz is divided into 79 channels, each with a band-width of 1 MHz. The ISM frequency band is freely available to everybody. It is used for medical research, microwave ovens and radio remote controls for garage door openers.
To prevent interference from other electrical equipment and to increase call-monitoring security, the channels are changed 1600 times every second, see illustration.
| Key | Explanation | Key | Explanation |
|---|---|---|---|
| f [GHz] | Frequency in gigahertz | t [s] | Time in seconds |
Data and speech
A band-width of approx. 1 MBit/s is available for bluetooth. This allows both speech and data to be transmitted, e.g.
- Audio data
- Telephone directory entries
- Operating status of bluetooth mobile phone
Call-monitoring security
Call-monitoring security is increased by the following measures:
- Frequency change (1600 times per second).
- Encryption:
- Every bluetooth-compatible unit has its own 48-bit address.
- All data transmitted can be encrypted and deciphered with a key up to 128 bit long.
- The relatively short range of approx.10 meters makes it difficult to manipulate the data communication. The data communications can only be manipulated from within the immediate vicinity of the Telematic Control Unit (TCU).