Bluetooth Radio Standard: E60, E61, E63, E64, E90, E91
Bluetooth radio standard
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 the space of up to 10 m to be networked together. 4 bluetooth mobile phones can be coupled to the TCU control unit. However, only one of the coupled bluetooth mobile phones can be used for communication.
The vehicle's bluetooth connection can be permanently deactivated using the display in the vehicle. This is necessary, e.g. if bluetooth is not approved due to legal stipulations in certain countries.
| Item | Description | Item | Description |
|---|---|---|---|
| 1 | Bluetooth mobile phone | 2 | Mobile digital assistant (MDA) with bluetooth interface |
| 3 | Personal digital assistant (PDA) with bluetooth interface | 4 | Laptop with bluetooth interface (no operation currently possible with the TCU) |
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. To prevent malfunctions in other electrical equipment and to increase call-monitoring security, the channel is changed 1600 times every second. The ISM frequency band can be freely used by anybody. It is used for medical research, for microwave ovens and for radio remote controls for garage doors systems.
Transmission quality
The transmission quality of the hands-free system deteriorates if objects extend into the transmission and reception range.
| Item | Description | Item | Description |
|---|---|---|---|
| f [GHz] | Frequency in gigahertz | t [s] | Time in seconds |
Data and speech
Voice information and data can be transmitted with the bluetooth. A band-width of approximately 1 MBit/s is available for transferring audio data, the phone book and operating status of the bluetooth phone.
Call-monitoring security
Call-monitoring security is increased by the following measures:
- Frequency change (1600 times per second).
- Applied encryption procedure
- 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.
This makes it possible to distinguish up to 281 trillion different units.
- The relatively short range of approx. 10 m makes it more difficult to manipulate the flow of data. The flow of data can only be manipulated from within the immediate vicinity of the Telematic Control Unit (TCU).