Black Box Explains...Wireless Ethernet standards.
The precursor to 802.11b, IEEE 802.11 was introduced in 1997. It was a beginning, but 802.11 only supported speeds up to 2 Mbps. And it supported two entirely different... more/see it nowmethods of encodingFrequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). This led to confusion and incompatibility between different vendors equipment.
802.11b is comfortably established as the most popular wireless standard. With the IEEE 802.11b Ethernet standard, wireless is fast, easy, and affordable. Wireless devices from all vendors work together seamlessly. 802.11b is a perfect example of a technology that has become both sophisticated and standardized enough to really make life simpler for its users.
The 802.11b extension of the original 802.11 standard boosts wireless throughput from 2 Mbps all the way up to 11 Mbps. 802.11b can transmit up to 200 feet under good conditions, although this distance may be reduced considerably by the presence of obstacles such as walls.
This standard uses DSSS. With DSSS, each bit transmitted is encoded and the encoded bits are sent in parallel across an entire range of frequencies. The code used in a transmission is known only to the sending and receiving stations. By transmitting identical signals across the entire range of frequencies, DSSS helps to reduce interference and makes it possible to recover lost data without retransmission.
The 802.11a wireless Ethernet standard is new on the scene. It uses a different band than 802.11b—the 5.8-GHz band called U-NII (Unlicensed National Information Infrastructure) in the United States. Because the U-NII band has a higher frequency and a larger bandwidth allotment than the 2.4-GHz band, the 802.11a standard achieves speeds of up to 54 Mbps. However, its more limited in range than 802.11b. It uses an orthogonal frequency-division multiplexing (OFDM) encoding scheme rather than FHSS or DSSS.
802.11g is an extension of 802.11b and operates in the same 2.4-GHz band as 802.11b. It brings data rates up to 54 Mbps using OFDM technology.
Because it's actually an extension of 802.11b, 802.11g is backward-compatible with 802.11b—an 802.11b device can interface directly with an 802.11g access point. However, because 802.11g also runs on the same three channels as 802.11b, it can crowd already busy frequencies.
Super G® is a subset of 802.11g and is a proprietary extension of the 802.11g standard that doubles throughput to 108 Mbps. Super G is not an IEEE approved standard. If you use it, you should use devices from one vendor to ensure compatibility. Super G is generally backwards compatible with 802.11g.
80211n improves upon 802.11g significantly with an increase in the data rate to 600 Mbps. Channels operate at 40 MHz doubling the channel width from 20 MHz. 802.11n operates on both the 2.4 GHz and the 5 GHz bands. 802.11n also added multiple-input multiple-output antennas (MIMO).
Multiple-Input/Multiple-Output (MIMO) is a part of the new IEEE 802.11n wireless standard. It’s a technique that uses multiple signals to increase the speed, reliability, and coverage of wireless networks. It transmits multiple datastreams simultaneously, increasing wireless capacity to up to 100 or even 250 Mbps.
This wireless transmission method takes advantage of a radio transmission characteristic called multipath, which means that radio waves bouncing off surfaces such as walls and ceilings will arrive at the antenna at fractionally different times. This characteristic has long been considered to be a nuisance that impairs wireless transmission, but MIMO technology actually exploits it to enhance wireless performance.
MIMO sends a high-speed data stream across multiple antennas by breaking it into several lower-speed streams and sending them simultaneously. Each signal travels multiple routes for redundancy.
To pick up these multipath signals, MIMO uses multiple antennas and compares signals many times a second to select the best one. A MIMO receiver makes sense of these signals by using a mathematical algorithm to reconstruct the signals. Because it has multiple signals to choose from, MIMO achieves higher speeds at greater ranges than conventional wireless hardware does. collapse
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Black Box Explains…HDMI
The High-Definition Multimedia Interface (HDMI®) is the first digital interface to combine uncompressed high-definition video, up to eight channels of uncompressed digital audio, and intelligent format and command data in... more/see it nowa single cable. It is now the de facto standard for consumer electronics and high-definition video and is gaining ground in the PC world.
HDMI supports standard, enhanced, and high-definition video. It can carry video signals at resolutions beyond 1080p at 60 Hz (Full HD) up to 4K x 2K (4096 x 2160) as well as 3D TV.
HDMI also provides superior audio clarity. It supports multiple audio formats from standard stereo to multichannel surround sound.
HDMI offers an easy, standardized way to set up home theaters and AV equipment over one cable. Use it to connect audio/video equipment, such as DVD players, set-top boxes, and A/V receivers with an audio and/or video equipment, such as a digital TVs, PCs, cameras, and camcorders. It also supports multiple audio formats from standard stereo to multichannel surround sound. Plus it provides two-way communications between the video source and the digital TV, enabling simple remote, point-and-click configurations.
NOTE: HDMI also supports HDCP (High-bandwidth Digital Content Protection), which prevents the copying of digital audio and video content transmitted over HDMI able. If you have a device between the source and the display that supports HDMI but not HDCP, your transmission won't work, even over an HDMI cable.
HDMI offers significant benefits over older analog A/V connections. It's backward compatible with DVI equipment, such as PCs. TVs, and other electronic devices using the DVI standard. A DVI-to-HDMI adapter can be used without a loss of video quality. Because DVI only supports video signals, no audio, the DVI device simply ignores the extra audio data.
The HDMI standard was introduced in December 2002. Since then, there have been a number of versions with increasing bandwidth and/or transmission capabilities.
With the introduction of HDMI (June 2006), more than doubled the bandwidth from 4.95 Gbps to 10.2 Gbps (340 MHz). It offers support for 16-bit color, increased refresh rates, and added support for 1440p WQXGA. It also added support for xvYCC color space and Dolby True HD and DTS-HD Master Audio standards. Plus it added features to automatically correct audio video synchronization. Finally, it added a mini connector.
HDMI 1.3a (November 2006), HDMI 1.3b (March 2007, HDMI 1.3b1 (November 2007), and 1.3c (August 2008) added termination recommendations, control commands, and other specification for testing, etc.
HDMI 1.4 (May 2009) increased the maximum resolution to 4Kx 2K (3840 x 2160 p/24/25/30 Hz). It added an HDMI Ethernet channel for a 100-Mbps connection between two HDMI devices. Other advancements include: an Audio Return Channel, stereoscopic 3D over HDMI (HDMI 1.3 devices will only support this for 1080i), an automotive connection system, and the micro HDMI connector.
HDMI 1.4a (March 2010) adds two additional 3D formats for broadcast content.
HDMI 2.0 (August 2013), which is backwards compatible with earlier versions of the HDMI specification, significantly increases bandwidth up to 18 Gbps and adds key enhancements to support market requirements for enhancing the consumer video and audio experience.
HDMI 2.0 also includes the following advanced features:
Resolutions up to 4K@50/60 (2160p), which is four times the clarity of 1080p/60 video resolution, for the ultimate video experience.
Up to 32 audio channels for a multi-dimensional immersive audio experience.
Up to 1536Hz audio sample frequency for the highest audio fidelity.
Simultaneous delivery of dual video streams to multiple users on the same screen.
Simultaneous delivery of multi-stream audio to multiple users (up to four).
Support for the wide angle theatrical 21:9 video aspect ratio.
Dynamic synchronization of video and audio streams.
CEC extensions provide more expanded command and control of consumer electronics devices through a single control point.
Standard HDMI Cable: 1080i and 720p
Standard HDMI Cable with Ethernet
Automotive HDMI Cable
High Speed HDMI Cable: 1080p, 4K, 3D and Deep Color
High Speed HDMI Cable with Ethernet
There are four HDMI connector types.
Type A: 19 pins. It supports all SDTV, EDTV, and HDTV modes. It is electrically compatible with single-link DVI-D. HDMI 1.0 specification.
Type B: 29 pins. Offers double the video bandwidth of Type A. Use for very high-resolution displays such as WQUXGA. It's electronically compatible with dual-link DVI-D. HDMI 1.0 specification.
Type C Mini: 19 pins. This mini connector is intended for portable devices. It is smaller than Type A but has the same pin configuration and can be connected to Type A cable via an adapter or adapter cable. Type C is defined in HDMI 1.3.
Type D Micro: 19 pins. This also has the 19-pin configuration of Type A but is about the size of a micro-USB connector. Type D is defined in HDMI 1.4.
Recently, HDMI Licensing, LLC announced that all able would be tested as either Standard or High-Speed cables. Referring to cables based on HDMI standard (e.g. 1.2, 1.3 etc.) is no longer allowed.
Standard HDMI cable is designed for use with digital broadcast TV, cable TV, satellites TV, Blu-ray, and upscale DVD payers to reliably transmit up to 1080i or 720p video (or the equivalent of 75 MHz or up to 2.25 Gbps).
High-Speed HDMI reliably transmits video resolutions of 1080p and beyond, including advanced display technologies such as 4K, 3D, and Deep Color. High-Speed HDMI is the recommended cable for 1080p video. It will perform at speeds of 600 MHz or up to 18 Gbps, the highest bandwidth urgently available over an HDMI cable.
HDCP copy protection
HDMI also supports High-bandwidth Digital Content Protection (HDCP), which prevents the copying of content transmitted over HDMI cable. If you have a device between the source and the display that supports HDMI but not HDCP, your transmission won’t work, even over an HDMI cable.
Additional resources and licensing information is available at HDMI.org.
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Black Box Explains... Digital Visual Interface (DVI).
The Digital Visual Interface (DVI) video standard is based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to... more/see it nowa low level to create transitions that convey data. To minimize the number of tran-sitions needed to transfer data, TMDS
uses a pair of signal wires. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy.
Although there are four types of DVI connectors, only DVI-D and DVI-I are commonly used for monitors. DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections. collapse