Overview

Bluetooth® is an international wireless communication protocol. It includes software and hardware, which allows secure, two-way audio or data streaming between Bluetooth devices such as computers, mobile phones and PDA's. Bluetooth devices send data and voice in a clean, clear, digital format up to 10 meters.

Introduction

Bluetooth is a short-range, wireless, digital communication standard. Devices with Bluetooth technology can carry either audio information or data from one device to another — computers and their peripherals, telephones, entertainment systems, personal digital assistants and more — in a rapidly growing community of electronic innovation. In achieving connectivity across devices, Bluetooth also eliminates the problems of routing and sorting the many wires, cables, connectors and plugs that would otherwise be needed to link devices.

Bluetooth provides agreement across devices at the physical level by using radio frequency transmission in the 2.4-gigahertz ISM (Industrial Scientific Medical) band. It also provides agreement on communication protocols: in order to communicate accurately, devices must agree on the scheduling and packaging of bits of data so they are understood at both ends of the line.

Bluetooth devices send data and voice in a clean, clear, digital format. Since it is digital, the audio signal is not subject to the same sources of signal degradation that sometimes compromise the quality of analog (FM, AM or inductive) transmissions. In an analog signal path, electrical noise from a variety of sources is amplified along with the signal. In contrast, a digital Bluetooth signal is extracted from the noise; it alone is transmitted and amplified, while noise is rejected (Figure 1).

	FM Transmitter		Analog FM Signal and Noise		FM Receiver		Signal and Noise at Output
Speech Input	Electrical Noise
	Bluetooth Transmitter		Digital Signal and Noise		Bluetooth Receiver		Clean Output Signal is Extracted, Noise is Rejected

Figure 1.
One advantage of Bluetooth devices is that the audio signal is not subject to the same sources of signal degradation that sometimes accompany FM, AM or inductive transmission technologies.

 The low-power design of Bluetooth transmission systems has two advantages. It minimizes battery consumption for portable devices. Also, it places an intentional limit on the range of transmission — the most common version has a range of 10 meters — which helps to avoid interference among nearby devices. At the same time, walls and other obstacles have a negligible effect on Bluetooth transmission.

The Bluetooth™ word mark and logos are owned by the Bluetooth SIG, Inc. and any use of such marks by Starkey Labs is under license. Other trademarks and trade names are those of their respective owners.