Archive for the ‘ Audio Video Systems ’ Category

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

Portable Media Player (PMP) and Their Reviews

Intro:

A portable media player (PMP) is a consumer electronics device that is capable of storing and playing digital media such as  audio, images, video, documents, etc. Digital audio players (DAP) that can also display images and play videos are usually called PMPs. Like DAPs, the data is typically stored on a hard drive, microdrive, or flash memory.

Other types of electronic devices like cellphones, internet tablets, and digital cameras are sometimes referred as PMPs because of their playback capabilities. This article however focuses on portable devices that have the main function of  playing media.

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History:
In late 1998, one of the first portable media players was introduced, the Rio PMP300. The iPod is a portable media player
designed and marketed by Apple and launched on October 23, 2001. In 2002, Archos first widely sold a portable media player, the Archos Jukebox Multimedia. Manufacturers have since implemented abilities to view images and play videos into their devices. In 2004, Microsoft attempted to take advantage of the growing PMP market by launching the Portable Media Center (PMC) platform. It was introduced at the 2004 Consumer Electronics Show with the announcement of the Zen Portable Media Center, which was co-developed by Creative. The Microsoft Zune series would later be based on the Gigabeat S, one of the PMC-implemented players.
Typical features:
PMPs are capable of playing digital audio, images, and video. Usually, a colour liquid crystal display (LCD) or organic light-emitting diode (OLED) screen is used as a display. Various players include the ability to record video, usually with the aid of optional accessories or cables, and audio, with a built-in microphone or from a line-out cable or FM tuner. Some players include readers for memory cards, which are advertised to equip players with extra storage or transferring media. In some players, features of a personal organizer are emulated, or support for games, like the iriver clix (through compatibility of Adobe Flash Lite) or the PlayStation Portable, is included.
Audio playback:
Nearly all players are compatible with the MP3 audio format, and many others support Windows Media Audio (WMA), Advanced Audio Coding (AAC) and WAV. Audio files purchased from online stores or ripped from CDs may include Digital Rights Management (DRM) copy protection, which most modern players support. Some players are compatible with open-source formats like Ogg Vorbis and the Free Lossless Audio Codec (FLAC). Every device has a bitrate limit on each compatible format.
Image viewing:
The JPEG format is compatible on all players that are capable of displaying images. Some players, like the iPod series, provide compatibility to display additional file formats like GIF, PNG, and TIFF, while others are bundled with conversion software.
Video playback:
Most newer players support the MPEG-4 video format, and many other players are compatible with Windows Media Video (WMV) and AVI, now mostly used as a container format. Recently, more and more players are enabling compatibility to the DivX video format and its open-source parallel, Xvid. Software included with the players may be able to convert video files into a compatible format.
Software:
PMPs are usually packaged with an installation CD/DVD that inserts device drivers (and for some players, software that is capable of seamlessly transferring files between the player and the computer). For recent players, however, these are usually available online via the manufacturers’ websites, or natively recognized by the operating system through Universal Mass Storage (UMS) or Media Transfer Protocol (MTP).
Hardware:
  • Storage:
As with DAPs, PMPs come in either flash or hard disk storage. Storage capacities have reached up to 64 GB for flash memory based PMPs, first reached by the 3rd Generation iPod Touch, and up to 500 GB for Hard disk drive PMPs, first achieved by the Archos 5 Internet Tablet.
A number of players support memory card slots, including CompactFlash (CF), Secure Digital (SD), and Memory Sticks. They are used to directly transfer content from external devices, and expanding the storage capacity of PMPs.
  • Interface:
A standard PMP uses a 5-way D-pad to navigate, however there have been many alternatives used. Most notable are the wheel and touch mechanisms seen on players from the iPod and Sansa series. Another popular mechanism is the swipe-pad, or ‘squircle,’ first seen on the Zune. Additional buttons are commonly seen for features such as volume control.
  • Screen:
Sizes range all the way up to 7 inches. As well, resolutions also vary, going up to WVGA. Most screens come with a color depth of 16-bit, but higher quality video oriented devices may range all the way to 24-bit, otherwise known as Truecolor, with the ability to display 16.7 million distinct colors. Screens commonly have a matte finish but may also come in glossy to increase color intensity and contrast. More and more devices are now also coming with touch screen as a form of primary or alternate input. This can be for convenience and/or aesthetic purposes. Certain devices, on the other hand, have no screen whatsoever, reducing costs at the expense of ease of browsing through the media library.
Radio:
Some portable media players include a radio receiver, most frequently receiving FM.
Other features:
Some portable media players have recently added features such as simple camera, built in game emulation (playing Famicon or other game formats from ROM images) and simple text readers and editors.
source: Wikipedia.