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BLUE TOOTH

introduction

There are lots of different ways that electronic devices can connect to one another. For example:
• Many desktop computer systems have a CPU unit connected to a mouse, a keyboard, a printer and so on.
• A personal digital assistant (PDA) will normally connect to the computer with a cable and a docking cradle.
• A TV will normally connect to a VCR and a cable box, with a remote control for all three components.
• A cordless phone connects to its base unit with radio waves, and it may have a headset that connects to the phone with a wire.
• In a stereo system, a CD player and other audio devices connect to the receiver, which connects to the speakers.

When you use computers, entertainment systems or telephones, the various pieces and parts of the systems make up a community of electronic devices. These devices communicate with each other using a variety of wires, cables, radio signals and infrared light beams, and an even greater variety of connectors, plugs and protocols.
The art of connecting things is becoming more and more complex every day. We sometimes feel as if we need a Ph.D. in electrical engineering just to set up the electronics in our homes! In this edition of HowStuffWorks, we will look at a completely different way to form the connections, called Bluetooth. Bluetooth is wireless and automatic, and has a number of interesting features that can simplify our daily lives.
The Problems
When any two devices need to talk to each other, they have to agree on a number of points before the conversation can begin. The first point of agreement is physical: Will they talk over wires, or through some form of wireless signals? If they use wires, how many are required -- one, two, eight, 25? Once the physical attributes are decided, several more questions arise:
• Information can be sent 1 bit at a time in a scheme called serial communications, or in groups of bits (usually 8 or 16 at a time) in a scheme called parallel communications. A desktop computer uses both serial and parallel communications to talk to different devices: Modems, mice and keyboards tend to talk through serial links, while printers tend to use parallel links.
• All of the parties in an electronic discussion need to know what the bits mean and whether the message they receive is the same message that was sent. In most cases, this means developing a language of commands and responses known as a protocol. Some types of products have a standard protocol used by virtually all companies so that the commands for one product will tend to have the same effect on another. Modems fall into this category. Other product types each speak their own language, which means that commands intended for one specific product will seem gibberish if received by another. Printers are like this, with multiple standards like PCL and PostScript
Companies that manufacture computers, entertainment systems and other electronic devices have realized that the incredible array of cables and connectors involved in their products makes it difficult for even expert technicians to correctly set up a complete system on the first try. Setting up computers and home entertainment systems becomes terrifically complicated when the person buying the equipment has to learn and remember all the details to connect all the parts. In order to make home electronics more user friendly, we need a better way for all the electronic parts of our modern life to talk to each other. That's where Bluetooth comes in.
Bluetooth Basics
Bluetooth is a standard developed by a group of electronics manufacturers that allows any sort of electronic equipment -- from computers and cell phones to keyboards and headphones -- to make its own connections, without wires, cables or any direct action from a user. Bluetooth is intended to be a standard that works at two levels:
• It provides agreement at the physical level -- Bluetooth is a radio-frequency standard.
• It also provides agreement at the next level up, where products have to agree on when bits are sent, how many will be sent at a time and how the parties in a conversation can be sure that the message received is the same as the message sent.
The companies belonging to the Bluetooth Special Interest Group, and there are more than 1,000 of them, want to let Bluetooth's radio communications take the place of wires for connecting peripherals, telephones and computers.
There are already a couple of ways to get around using wires. One is to carry information between components via beams of light in the infrared spectrum. Infrared refers to light waves of a lower frequency than human eyes can receive and interpret. Infrared is used in most television remote control systems, and with a standard called IrDA (Infrared Data Association) it's used to connect some computers with peripheral devices. For most of these computer and entertainment purposes, infrared is used in a digital mode -- the signal is pulsed on and off very quickly to send data from one point to another.