Wednesday, July 23, 2008

FYI: Bluetooth

BlueSoleil.com > Bluetooth Overview
Why is it called Bluetooth?
In 1998, a special interest group (SIG) was formed to develop and promote the technology. The SIG took the name from Harald II "Bluetooth" King of Denmark who was born in the 10th century. Bluetooth peacefully unified Denmark and Norway.

What is the Bluetooth SIG?

The Bluetooth SIG was formed as a group of companies working together to define, develop and promote an open, royalty-free specification for seamless wireless connectivity and cable replacement for a wide variety of mobility-enhancing devices.

Who are the members of the SIG?
The founding SIG members are Ericsson, Intel, IBM, Nokia, and Toshiba. Since then over 2000 adopter companies have joined including HP, Lucent, Motorola, and 3Com.

How does Bluetooth work?
Bluetooth
uses a frequency hopping spread spectrum technique. Spectrum spreading is accomplished by frequency hopping up to 1600 hops per second on 79 channels between 2.402 GHz and 2.480 GHz.

Bluetooth radio modules avoid interference from other signals by hopping to a new frequency after transmitting or receiving a data packet. The sophisticated mode of transmission adopted in the Bluetooth specification ensures protection from interference and seeks to insure the security of the data.

In what frequency range do Bluetooth devices operate?
Bluetooth operates in the 2.4 GHz range referred to as the Instrumentation, Scientific, and Medical (ISM) band. This band provides license-free operation in the United States, Europe, Japan, and most industrialized nations worldwide.

What is the transfer speed?
The gross data rate of Bluetooth 1.1 is 1 Mbps. The protocol splits that bandwidth to support both voice and data communication. Bluetooth can support an asynchronous data channel, up to three simultaneous synchronous voice channels, or a channel, which simultaneously supports asynchronous data and synchronous voice. Each voice channel supports a 64 Kbps synchronous (voice) link. The asynchronous data channel can support an asymmetric link of up to 721 Kbps in either direction, while permitting 57.6 Kbps in the return direction or a symmetric link up to 432.6 Kbps.

The gross data rate of Bluetooth 2.0, the EDR version (Enhanced Data Rate), is up to 3Mbps.

What is the range of Bluetooth?

The link range is up to 10 meters using a 0 dBm radio. The range is extended up to 100 meters using a +20 dBm radio.

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