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How To Bluetooth and Bluetooth History

Bluetooth History:
Bluetooth is a wireless technology for exchanging data over distance, mobile devices or computers, creating personal area networks with high security. Bluetooth is Created by Ericsson company in 1994, it was conceived as a wireless alternative to RS-232 data cables. It can be connect with several devices, due to problems of synchronization. Bluetooth services was firstly developed by Jaap Haartsen and Sven Mattisson when they were working for Ericsson in Sweden.
Bluetooth is controlled by “Bluetooth Special Interest Group”, which has 14,000+ member companies in the field of telecommunication, computing, networking, and consumer electronics. To be marketed as a Bluetooth device, it must be qualified with the standards of SIG. Network of patent is required to implement the technology and only licensed to those qualifying devices.

Name And Logo:

Bluetooth word is an anglicised version of the Scandinavian Blåtand. Bluetooth Logo comes from bind rune merging the Younger Futhark runes Hagall, Bjarkan, Haralds initials.

Setting up connections:

Any Bluetooth in discoverable mode will transmit following info (on demand):Device name, Device class, List of services.
Any device may perform inquiry or respond to find or configure other devices to connect. if the device is trying to connect knows the address of other device, it always replys to direct connection requests and transmits the information shown in the list above if requested. Use of a device services might require pairing or acception by its owner, but the connection itself can be initiated by any device and held. Some Bluetooth devices can be connect with only one device at a moment.

Every Bluetooth device has its own unique 48-bit address. these addresses are generally not shown. Instead of that address friendly Bluetooth names are used, which can be set by device user. That names appears when another user scans for devices.

Most phones have the Bluetooth name set with manufacture or model of phone by defaulted by company. Most of phones and laptops shows only Bluetooth names and some special programs are required to get additional information about such device.

Implementation:

Bluetooth is running by radio technology which is called frequency hopping spread spectrum, that chops up several data being sent and transmits chunks of it on up to 79 bands (1 MHz each; centered from 2402 to 2480 MHz) in the range 2,400-2,483.5 MHz (allowing for guard bands). This range is in the globally unlicensed Industrial, Scientific and Medical (ISM) 2.4GHz short-range radio frequency band.

Bluetooth provides a security to connect or exchange information or data between several devices such as fax machines, mobile phones, laptop notebooks, PCs, PRinting Machines, GPS receivers, Digital Cameras and also video game consoles.

Communication System:

Major Bluetooth devices can communicate with up to seven devices in a piconet at a time. At any time, data could be transferred between the main and one other device. The master bluetooth chooses which slave device to address, typically, it switches rapidly from another device in a round-robin fashion. Bluetooth provides for the connection of two or more piconets to form a scatternet, in this system certain devices serve as bridges, and they playing the master role in one piconet and the slave role in another.

Most of USB Bluetooth adapters or “dongles” are available, some from them also include an IrDA adapter. In starting Bluetooth dongles, however, have limited capabilities, providing only the Bluetooth Enumerator and a low powerful Bluetooth Radio incarnation. These devices can link computers with Bluetooth with a distance of 100 meters, but they do not offer as many services like modern adapters.

Bluejacking:

Bluejacking is the sending of picture or message from one bluetooth user to another suspicious user through Bluetooth wireless technology. Applications include short messages (e.g., You have just been hacked by bluejack!). Bluejacking is not involve in the removal of any data from the device. Bluejacking can be involve taking control of a mobile wirelessly or phoning a premium rate line, which is owned by the bluejacker.

Future:

In future we will see bluetooth in every field, when childern uses bluetooth for their education purposes and for the copying of their homework as well, office use this service for their customers and employees to check their work and demands. Bluetooth will play important role for medical services. Hope these services will never used for teasing someone or community.

Helped from wikipedia.org

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History Of Cables And Cords

History, Types and Biography of cables.

Electrical cables may be made more flexible by stranding the wires. In this process, smaller individual wires are twisted or braided together to produce larger wires that are more flexible than solid wires of similar size. Bunching small wires before concentric stranding adds the most flexibility. Copper wires in a cable may be bare, or they may be plated with a thin layer of another metal, most often tin but sometimes gold, silver or some other material. Tin, gold, and silver are much less prone to oxidation than copper, which may lengthen wire life, and makes soldering easier. Tinning is also used to provide lubrication between strands. Tinning was used to help removal of rubber insulation. Tight lays during stranding makes the cable extensible (CBA – as in telephone handset cords).Cables can be securely fastened and organized, such as by using trunking, cable trays, cable ties or cable lacing. Continuous-flex or flexible cables used in moving applications within cable carriers can be secured using strain relief devices or cable ties.At high frequencies, current tends to run along the surface of the conductor. This is known as the skin effect.

Cables and electromagnetic fields

Any current-carrying conductor, including a cable, radiates an electromagnetic field. Likewise, any conductor or cable will pick up energy from any existing electromagnetic field around it. These effects are often undesirable, in the first case amounting to unwanted transmission of energy which may adversely affect nearby equipment or other parts of the same piece of equipment; and in the second case, unwanted pickup of noise which may mask the desired signal being carried by the cable, or, if the cable is carrying power supply or control voltages, pollute them to such an extent as to cause equipment malfunction.The first solution to these problems is to keep cable lengths in buildings short, since pick up and transmission are essentially proportional to the length of the cable. The second solution is to route cables away from trouble. Beyond this, there are particular cable designs that minimize electromagnetic pickup and transmission. Three of the principal design techniques are shielding, coaxial geometry, and twisted-pair geometry.Shielding makes use of the electrical principle of the Faraday cage. The cable is encased for its entire length in foil or wire mesh. All wires running inside this shielding layer will be to a large extent decoupled from external electric fields, particularly if the shield is connected to a point of constant voltage, such as earth. Simple shielding of this type is not greatly effective against low-frequency magnetic fields, however – such as magnetic “hum” from a nearby power transformer. A grounded shield on cables operating at 2 kV or more gathers leakage current and capacitive current, protecting people from electric shock and equalizing stress on the cable insulation.Coaxial design helps to further reduce low-frequency magnetic transmission and pickup. In this design the foil or mesh shield is perfectly tubular – i.e. with a circular cross section – and the inner conductor (there can only be one) is situated exactly at its center. This causes the voltages induced by a magnetic field between the shield and the core conductor to consist of two nearly equal magnitudes which cancel each other.The twisted pair is a simple expedient where two wires of a cable, rather than running parallel to each other, are twisted around each other, forming a pair of intertwined helices. This can be achieved by putting one end of the pair in a hand drill and turning while maintaining moderate tension on the line. Field cancellation between successive twists of the pair considerably reduces electromagnetic pickup and transmission.Power-supply cables feeding sensitive electronic devices are sometimes fitted with a series-wired inductor called a choke which blocks high frequencies that may have been picked up by the cable, preventing them from passing into the device.

Fire protection

In building construction, electrical cable jacket material is a potential source of fuel for fires. To limit the spread of fire along cable jacketing, one may use cable coating materials or one may use cables with jacketing that is inherently fire retardant. The plastic covering on some metal clad cables may be stripped off at installation to reduce the fuel source for accidental fires. In Europe in particular, it is often customary to place inorganic wraps and boxes around cables in order to safeguard the adjacent areas from the potential fire threat associated with unprotected cable jacketing. However, this fire protection also traps heat generated from conductor losses, so the protection must be thin.There are two methods of providing fire protection to a cable:Insulation material is deliberately added up with fire retardant materialsThe copper conductor itself is covered with mineral insulation (MICC cables)

Electrical cable types

Basic cable types are as follows:

Shape: Ribbon cable

Construction: Based on construction and cable properties it can be sorted into the following: Coaxial cable, Mineral-insulated copper-clad cable, Twinax cable, Flexible cables, Non-metallic sheathed cable (or nonmetallic building wire,  NM,  NM-B), Metallic sheathed cable (or armored cable, AC, or BX), Multicore cable (consist of more than one wire and is covered by cable jacket), Shielded cable, Single cable (from time to time this name is used for wire), Twisted pair, Twisting cable, Special Arresting cable, Bowden cable, Heliax cable, Direct-buried cable, Heavy-lift cable, Elevator cable.

Application

Audiovisual cable

Bicycle cable

Communications cable

Computer cable

Mechanical cable

Sensing cable

Submersible cable

Wire rope (wire cable)

Thanks to Wikipedia.org