An extended synchronous transfer mode (enhanced SCO ESCO) was introduced. This new packet types offer a more flexible organization of the transfer period. Also, this allows use of other audio formats such as the SBC codec to be introduced in the HFP version 2.0 and USB i2c.

Currently Bluetooth can offer the asynchronous transmission. Bluetooth data packets consist of a 72-bit access code, a 54-bit header and a variable payload of 0 bits to 2745 bits (DH5 packet type) length. Bluetooth 2.0 + EDR ° up to 8168 bits of user data per package (3-DH5) are possible.

Bluetooth is designed for the transfer of data between devices over short distances via radio technology (WPAN). Other aspects were added primarily by Nokia and Intel. Bluetooth frequencies can communicate with each other via the small mobile devices such as mobile phones and PDAs as well as computers and peripherals. The main purpose of Bluetooth is to replace cable connections via USB i2c between devices.

Technical Background

Devices working according to the standards of the Bluetooth SIG send as Short Range Devices (SRD) in a license-free ISM band (Industrial, Scientific and Medical band) between 2.402 GHz and 2.480 GHz. They may be used license-free worldwide. Interference can also be caused for example by wireless networks, cordless phones and microwave ovens that operate in the same frequency band.

To achieve robustness against interference, frequency hopping is used, in which the frequency band is divided into 79 different frequency levels in the 1-MHz spacing, which are changed up to 1600 times per second. However, there are also types of packets in which the frequency is not changed regularly (multi-slot packets and USB i2c). The top and bottom end, there is a respective frequency band and guard band (guard band) to adjacent frequency bands. Theoretically, a data transfer rate of 706.25 kbit/s for simultaneous reception at 57.6 kbit/s can be achieved when sending (asymmetrical data transmission).

As of version 2.0, Bluetooth can achieve about three times faster data transfer rate than with EDR (Enhanced Data Rate), ie around 2.1 Mbit/s Starting from version 1.1, a Bluetooth device at the same time maintain up to seven connections, whereby the participating devices must share the available bandwidth (shared medium and USB i2c).

Bluetooth supports the transmission of voice and data. However, most devices can only manage three participants in a piconet during the transmission of voice due to synchronous communication.

The memory card reader is a peripheral that reads or writes to flash memory media. Currently, computers (including a plate or via USB), DVD players and other devices, often read various types of cards.