30-12-2010, 01:42 PM
Definition
The communications capability of devices and continuous transparent information routes are indispensable components of future oriented automation concepts. Communication is increasing rapidly in industrial environment even at field level.In any industry the process can be realized through sensors and can be controlled through actuators. The process is monitored on the central control room by getting signals through a pair of wires from each field device in Distributed Control Systems (DCS). With advent in networking concept, the cost of wiring is saved by networking the field devices. But the latest trend is elimination of wires i.e., wireless networks.
Wireless sensor networks - networks of small devices equipped with sensors, microprocessor and wireless communication interfaces.In 1994, Ericsson Mobile communications, the global telecommunication company based in Sweden, initiated a study to investigate, the feasibility of a low power, low cost ratio interface, and to find a way to eliminate cables between devices. Finally, the engineers at the Ericsson named the new wireless technology as "Blue tooth" to honour the 10th century king if Denmark, Harald Blue tooth (940 to 985 A.D).
The goals of blue tooth are unification and harmony as well, specifically enabling different devices to communicate through a commonly accepted standard for wire less connectivity.
BLUE TOOTH
Blue tooth operates in the unlicensed ISM band at 2.4 GHZ frequency band and use frequency hopping spread spectrum technique. A typical Blue tooth device has a range of about 10 meters and can be extended to 100meters. Communication channels supports total bandwidth of 1 Mb / sec. A single connection supports a maximum asymmetric data transfer rate of 721 KBPS maximum of three channels.
BLUE TOOTH - NETWORKS
In bluetooth, a Piconet is a collection of up to 8 devices that frequency hop together. Each Piconet has one master usually a device that initiated establishment of the Piconet, and up to 7 slave devices. Master's Blue tooth address is used for definition of the frequency hopping sequence. Slave devices use the master's clock to synchronize their clocks to be able to hop simultaneously.
A Piconet
When a device wants to establish a Piconet it has to perform inquiry to discover other Blue tooth devices in the range. Inquiry procedure is defined in such a way to ensure that two devices will after some time, visit the same frequency same time when that happens, required information is exchanged and devices can use paging procedure to establish connection.When more than 7 devices needs to communicate, there are two options. The first one is to put one or more devices into the park state. Blue tooth defines three low power modes sniff, hold and park. When a device is in the park mode then it disassociates from and Piconet, but still maintains timing synchronization with it. The master of the Piconet periodically broadcasts beacons (Warning) to invite the slave to rejoin the Piconet or to allow the slave to request to rejoin. The slave can rejoin the Piconet only if there are less than seven slaves already in the Piconet. If not so, the master has to 'park' one of the active slaves first.
All these actions cause delay and for some applications it can be unacceptable for eg: process control applications, that requires immediate response from the command centre (central control room).Scatternet consists of several Piconets connected by devices participating in multiple Piconet. These devices can be slaves in all Piconets or master in one Piconet and slave in other Piconets. Using scatternets higher throughput is available and multi-hop connections between devices in different Piconets are possible. i.e., The unit can communicate in one Piconet at time so they jump from pioneer to another depending upon the channel parameter.
INTRODUCTION
Bluetoothwireless technology is a cable replacement technology that provides wireless communication between portable devices, desktop devices and peripherals. It is used to swap data and synchronize files between devices without having to connect each other with cable. The wireless page link has a range of 10m which offers the user mobility. This technology can be used to make wireless data connection to conventional local area networks (LAN) through an access point. There is no need for the user to open an application or press button to initiate a process. Bluetooth wireless technology is always on and runs in the background. Bluetooth devices scan for other Bluetooth devices and when these devices are in range they start to exchange messages so they can become aware of each others capabilities. These devices do not require a line of sight to transmit data with each other. Within a few years about 80 percent of the mobile phones are expected to carry the Bluetooth chip. The Bluetooth transceiver operates in the globally available unlicensed ISM radio band of 2.4GHz. The ISM bands include frequency range at 902MHz to 928MHz and 2.4GHz to 2.484GHZ which do not require operator license from a regulatory agency. This means that Bluetooth technology can be used virtually anywhere in the world. Another type of wireless technology that is being used nowadays is infrared signals. The choice of using either one of the wireless technology will depend on the application for which it is being used. Bluetooth is an economical, wireless solution that is convenient, reliable, easy to use and operates over a longer distance than infrared. The initial development started in 1994 by Ericsson. Bluetooth now has a special interest group (SIG) which has 1800 companies worldwide. Bluetooth technology enables voice and data transmission in a short-range radio. There is a wide range of devises which can be connected easily and quickly without the need for cables. Soon people world over will enjoy the convenience, speed and security of instant wireless connection. Bluetooth is expected to be embedded in hundreds of millions mobile phones, PCs, laptops and a whole range of other electronic devices in the next few years. This is mainly because of the elimination of cables and this makes the work environment look and feel comfortable and inviting.
ORIGIN OF BLUETOOTH
In 1994, Ericsson Mobile Communication initiated a study to investigate the feasibility of a low power, low cost radio interface between mobile phones and their accessories. The aim of the study was to find a way to eliminate cables between mobile phones and PC cards, headsets, desktops and other devices. The study was part of a large project investigating how different communication devices could be connected to the cellular network via a mobile phone. Ericsson’s work in this area caught the attention of IBM, Intel, Nokia, and Toshiba. The companies formed the special interest group (SIG) in May 1998, which grew to over 1500 member companies by April 2000. The company jointly developed the Bluethooth 1.0 specifications, which was released in July 1999….
wireless technology is a cable replacement technology that providesBluetooth wireless communication between portable devices, desktop devices and peripherals. It is used to swap data and synchronize files between devices without having to connect each other with cable. The wireless page link has a range of 10m which offers the user mobility. This technology can be used to make wireless data connection to conventional local area networks (LAN) through an access point. There is no need for the user to open an application or press button to initiate a process. Bluetooth wirelesstechnology is always on and runs in the background. Bluetooth devices scan for other Bluetooth devices and when these devices are in range they start to exchange messages so they can become aware of each others capabilities. These devices do not require a line of sight to transmit data with each other. Within a few years about 80 percent of the mobile phones are expected to carry the Bluetooth chip. The Bluetooth transceiver operates in the globally available unlicensed ISM radio band of 2.4GHz. The ISM bands include frequency range at 902MHz to 928MHz and 2.4GHz to 2.484GHZ which do not require operator license from a regulatory agency. This means that Bluetooth technology can be used virtually anywhere in the world. Another type of wireless technology that is being used nowadays is infrared signals. The choice of using either one of the wireless technology will depend on the application for which it is being used. Bluetooth is an economical, wireless solution that is convenient, reliable, easy to use and operates over a longer distance than infrared. The initial development started in 1994 by Ericsson. Bluetooth now has a special interest group (SIG) which has 1800 companies worldwide. Bluetooth technology enables voice and data transmission in a short-range radio. There is a wide range of devises which can be connected easily and quickly without the need for cables. Soon people world over will enjoy the convenience, speed and security of instant wireless connection. Bluetooth is expected to be embedded in hundreds of millions mobile phones, PCs, laptops and a whole range of other electronic devices in the next few years. This is mainly because of the elimination of cables and this makes the work environment look and feel comfortable and inviting.
Advantages
Freedom from wires: This gadget improves the safety, as a result you really do not have to require the cables. Other benefit of using Bluetooth trimming is that you can without any difficulty can carry your laptop in your trip, with the other devices of Bluetooth without thinking about the bulky connection cables.
Luminosity on the pocket:
This accessory is very cheap, but almost every user thinks that this trimming is very expensive rather it is not. It is a lasting savings, with so much of discounts.
Global compatibility:
Bluetooth technology is worldwide, which means it is familiar and acknowledged across the world. This technology is so much advance that I do not have to mention more about the companies which produce this technique. But one thing is sure by now that users can easily depend on this technology for many years.
Completely mechanical:
This technique is completely mechanical, you do not have to press the keypad various time. When it comes in contact with the other touchtone phone having the same quality it started working by its own.
Without interlude:
Bluetooth facilitated devices have small, almost no obstruction from other wireless gadgets because they use a method known as, "frequency hopping" and low control wireless gesture.
Road security:
Bluetooth wireless car kits efficiently resolve the message and auditory troubles occurring while driving. This technology surely enlarges protection when it comes to driving with both hands on the steering wheel while having a hard obvious discussion on your mobile phone.
Little power utilize:
The Bluetooth technique requires a very little power to do its function. It only use the little power indicator. It helps in diminishing the electric power and the battery expenditure.
Identical function:
Developing standard wireless system promises the stro
Disadvantages:
Battery Use: This occurs mostly on your cell phone but also occurs in other technology such as music players. You’re using up more battery power when you leave your Bluetooth enabled on your phone all day. To disregard all this, the best thing that you can possibly do is disable it once you are completed with the transfer. It only takes a few seconds to enable and disable so it wouldn’t hurt to disable it once you are done using it.
Bluetooth Internet: Throughout all devices, when using Bluetooth internet, the connection can sometimes run very slow so Bluetooth internet is not highly suggested for all cases.
As you can notice that there are quite a bit of advantages and fewer disadvantages. Overall, Bluetooth is a great thing to be using on all your devices that supports it. You can do so much with it and includes cutting all the cords attached to your devices
