Bluetooth

 

 

Wireless Standard - Bluetooth

 

Introduction


This document is designed as a very brief introduction to the Bluetooth standard. The link page points to additional websites where more information is available.


Bluetooth technology was first developed by Ericsson and then formalized by a group of electronics manufacturers (Ericsson, IBM, Intel, Nokia, and Toshiba) who joined forces to form a private trade association known as the Bluetooth Special Interest Group (SIG).   Bluetooth is also an IEEE standard  IEEE 802.15..1.


Bluetooth operates in the 2.4 Gigahertz unlicensed frequency band.   It uses very low power and has limited range of about 1 meter to 30 meters depending on the Bluetooth hardware implementation. The most prevalent application is in cell telephones where it functions as a wireless audio link to a cell phone. This enables remote audio operation of the cell phone. This functionality has been expanded to numerous other application due to the addition of various communication profiles. Bluetooth can be used for wireless keyboards, mice, printers and other peripheral devices.


Bluetooth devices are able to avoid interference through a technique known as spread-spectrum frequency hopping. By using the “hopping” method, a device will use one of 79 different, randomly chosen frequencies within an assigned range, and will frequently change frequencies from one to another.

Bluetooth enabled devices, which all use the “hopping” method, change frequencies 1,600 times per second. As a result, more devices can use a portion of the radio spectrum.  The risk of a device like a cell phone or baby monitor interfering with Bluetooth devices is minimized, since any interference on a specific frequency will last for only a fraction of a second.

Bluetooth version 2.0 + EDR, the very latest of the Bluetooth specification versions, uses an enhanced technology called: Adaptive Frequency Hopping (AFH).  AFH allows Bluetooth devices to measure the quality of the wireless signal and then determine if there are bad channels present on specific frequencies due to interference from other wireless devices.  If bad channels are present on a specific frequency, the Bluetooth device will adjust its hopping sequence to avoid them. As a result, the Bluetooth connection is stronger, faster, and more reliable.

In December, 2009 an upgrade to the Bluetooth standard was approved. It is an ultra low power Bluetooth variation that is intended to be used with small button cell batteries for applications with watches and hand held devices. WiHART Systems offers Bluetooth modules for wireless connectivity and will offer low power technology when available.

WiHART Systems offers a Bluetooth wireless module for integration with other wireless platforms.  A description of the wireless Bluetooth module is here.

 

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