What is HDMI?

HDMI stands for High-Definition Multimedia Interface.  It is the first and only industry-supported, uncompressed, all-digital audio/video interface. By delivering crystal-clear, all-digital audio and video via a single cable, HDMI dramatically simplifies cabling and helps provide consumers with the highest-quality home theater experience. HDMI provides an interface between any audio/video source, such as a set-top box, DVD player, or A/V receiver and an audio and/or video monitor, such as a digital television (DTV), over a single cable.

HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio on a single cable. It transmits all ATSC HDTV standards and supports 8-channel, 192kHz, uncompressed digital audio and all currently-available compressed formats (such as Dolby Digital and DTS), HDMI 1.3 adds additional support for new lossless digital audio formats Dolby TrueHD and DTS-HD Master Audio with bandwidth to spare to accommodate future enhancements and requirements.

The HDMI Connector

The Standard

HDMI is the de facto standard digital interface for HD and the consumer electronics market: More than 700 companies have become adopters, and nearly 200 million devices featuring HDMI are expected to ship in 2008, with an installed based of nearly one billion HDMI devices by 2010 (conservative estimates by In-Stat).

HDMI is the interface for convergence of PC and consumer electronics devices: HDMI enables PCs to deliver premium media content including high definition movies and multi-channel audio formats. HDMI is the only interface enabling connections to both HDTVs and digital PC monitors implementing the DVI and HDMI standards.

HDMI is continually evolving to meet the needs of the market: Products implementing new versions of the HDMI specification will continue to be fully backward compatible with earlier HDMI products.

The Market Adopts HDMI

HDMI has become so successful, so quickly, because it meets the needs of all facets of the Consumer Electronics and PC ecosystem. Manufacturers now have an all digital pipeline from the source material to the display; content providers have an interface that protects their intellectual property; and consumers have and easy-to-use, high quality, plug-and-play interface for their home entertainment environment.

HDMI Benefits

Quality: HDMI maintains the audio in its pure digital form all the way to the amplifier. Analog audio connections are more prone to losses depending on the cabling and other electronics of the audio rendering device. Compared to SPDIF connections, HDMI has significantly more bandwidth, allowing it to support the latest lossless audio formats such as Dolby TrueHD and DTS-HS Master Audio. These formats can not be supported over SPDIF connections due to their very high data rate requirements that exceed the capabilities of SPDIF. Please also see section on HDMI 1.3 for further details on Dolby TrueHD and DTS-HD Master Audio formats.

Ease of Use: HDMI combines video and multi-channel audio into a single cable, eliminating the cost, complexity, and confusion of multiple cables currently used in A/V systems. This is particularly beneficial when equipment is being upgraded or added.

Intelligence: HDMI supports two-way communication between the audio source (such as a DVD player) and the audio rendering device (such as an A/V receiver), enabling new functionality such as automatic configuration and one-touch play. By using HDMI, devices automatically deliver the most effective format (e.g. Dolby Digital vs. 2-channel PCM) for the A/V receiver that it is connected to – eliminating the need for the consumer to scroll through all the audio format options to guess what is best and properly supported.

A New Interface

With the advent of high-definition content, analog interfaces were becoming increasingly limited in their ability to deliver the highest quality, high-definition content.

HDMI has no conversion or compression of signals:

With the delivery of 1080p content, analog interfaces are nearing the end of their ability to deliver high-definition content without highly compressing the signal, which can result in loss of data and signal quality. HDMI has the bandwidth to send uncompressed video so there is no loss of data or signal quality

Content Protection allows access to HD content:

Content providers, including all the major movie studios, have been clear that much of the studio content will not be released in high-definition over unprotected analog interfaces. They have designated HDMI and/or DVI as the only interfaces that will be allowed to carry this new HD content.

HDMI Digital allows two-way communication:

HDMI supports two-way communication between the video source (such as a DVD player) and the DTV, enabling new functionality such as automatic configuration and one-touch play. By using HDMI, devices automatically deliver the most effective format (e.g. 480p vs. 720p, 16:9 vs. 4:3) for the display that it is connected to – eliminating the need for the consumer to scroll through all the format options to guess what looks best.

HDMI & Entertainment Systems

The most tangible and immediate way that HDMI changes the way we interface with our components is in the set-up. One cable replaces up to 11 analog cables, highly simplifying the setting up of a home theater as well as supporting the aesthetics of new component design with cable simplification.

Typical DVD Player With HDMI Out

Next, when the consumer turns on the HDMI-connected system, the video is of higher quality since the signal has been neither compressed nor converted from digital to analog and back.

Lastly, because of the two-way communication capabilities of HDMI, components that are connected via HDMI constantly talk to each other in the background, exchanging key profile information so that content is sent in the best format without the user having to scroll through set-up menus. The HDMI specification also includes the option for manufacturers to include CEC functionality (Consumer Electronics Control), a set of commands that utilizes HDMI’s two-way communication to allow for single remote control of any CEC-enabled devices connected with HDMI. For example, CEC includes one-touch play, so that one touch of play on the DVD will trigger the necessary commands over HDMI for the entire system to power on and auto-configure itself to respond to the command. CEC has a variety of common commands as part of its command set, and manufacturers who implement CEC must do so in a way that ensures that these common command sets interoperate amongst all devices, regardless of manufacturer.

CEC is an optional feature, however, so consumer interested in this functionality must look for CEC in the product feature list. Also, it is important to know that some manufacturers are creating their own proprietary names for their implementation of the CEC command set.

Typical Large Screen TV With HDMI Connectors

HDMI Tips

How many inputs/outputs do you need?

More and more inputs and outputs on components are appearing as more and more people are connecting with HDMI. It is common to see 3 and 4 inputs on an HDTV – many with one input on the side or front for connecting to game consoles or other portable devices such as digital still cameras or camcorders. Always think about the number of sources and displays (or projectors) that could become part of your home theater system, and make sure the device you are evaluating has the number of inputs and outputs to support your needs over the near and long term.

For those who have existing systems with one or two inputs, and are finding they need more, there are HDMI switches in the market that switch from multiple inputs (sources) to one output (to your display).

Think features rather than HDMI version number. 

HDMI is constantly evolving to meet the needs of the marketplace. The standard is constantly adding more and more features that manufacturers can implement if they desire. But HDMI does not require manufacturers to implement everything that HDMI can do. HDMI provides a menu of capabilities and allows the manufacturer to choose which of those features make sense for its product line.

As a result, it is recommended that consumers look for products with the features they want, rather than the version number of the HDMI components. Version numbers reflect capabilities, but do not correspond to product features. For example, if you want the new video features called Deep Color, look for Deep Color in the feature set rather than HDMI 1.3, the version of the specification that enabled Deep Color. Why? Because the version of the specification that enables Deep Color (1.3) does not mandate that Deep Color functionality be implemented.

However, it is important to also note that all HDMI versions are backwards compatible, so not matter what version of HDMI is in the component, all HDMI-enabled components will work together at the highest level of shared functionality.

Convergence Between The PC And Consumer Electronics

HDMI was developed using the same technology as DVI (Digital Visual Interface), the digital connection standard for the PC environment. So, HDMI is fully compatible with all DVI-enabled PCs (since HDMI offers both audio and video over one cable, and DVI carried only video, DVI-HDMI connectivity requires a separate audio cable).

HDMI enables PCs to deliver premium media content including high definition movies and multi-channel audio formats. HDMI is the only interface enabling connections to both HDTVs and digital PC monitors implementing the DVI and HDMI standards – fully compatible with the hundreds of millions of DVI displays already in the market.

HDMI Cables

What is the difference between a “Standard” HDMI cable and a “High-Speed” HDMI cable?

Recently, the HDMI standards body announced that cables would be tested as Standard or High-Speed cables.

• Standard (or “category 1”) cables have been tested to perform at speeds of 75Mhz, which is the equivalent of a 1080i signal.
• High Speed (or “category 2”) cables have been tested to perform at speeds of 340Mhz, which is the highest bandwidth currently available over an HDMI cable and can successfully handle 1080p signals including those at increased color depths and/or increased refresh rates. High-Speed cables are also able to accommodate higher resolution displays, such as WQXGA cinema monitors (resolution of 2560 x 1600).

Does HDMI accommodate long cable lengths?

HDMI technology has been designed to use standard copper cable construction at long lengths. In order to allow cable manufacturers to improve their products through the use of new technologies, HDMI specifies the required performance of a cable but does not specify a maximum cable length. We have seen cables pass “Standard Cable” HDMI compliance testing at lengths of up to a maximum of 10 meters without the use of a repeater. It is not only the cable that factors into how long a cable can successfully carry an HDMI signal, the receiver chip inside the TV or projector also plays a major factor. Receiver chips that include a feature called “cable equalization” are able to compensate for weaker signals thereby extending the potential length of any cable that is used with that device.

With any long run of an HDMI cable, quality manufactured cables can play a significant role in successfully running HDMI over such longer distances.

HDMI FAQs

Q. How can I tell the differences in each version of the HDMI specification?

Download a copy of the most recent specification of HDMI. At the beginning of the document, there is a section called “Revision History.” In this section, you can view all of the the changes for each revision of the Specification.

Q. Are all of the new HDMI versions backward compatible with previous versions?

Yes, all HDMI versions are fully backward compatible with all previous versions.

Q. What’s new in the HDMI 1.3 Specification?

• Higher speed: Although all previous versions of HDMI have had more than enough bandwidth to support all current HDTV formats, including full, uncompressed 1080p signals, HDMI 1.3 increases its single-link bandwidth to 340 MHz (10.2 Gbps) to support the demands of future HD display devices, such as higher resolutions, Deep Color and high frame rates. In addition, built into the HDMI 1.3 specification is the technical foundation that will let future versions of HDMI reach significantly higher speeds.
• Deep Color: HDMI 1.3 supports 10-bit, 12-bit and 16-bit (RGB or YCbCr) color depths, up from the 8-bit depths in previous versions of the HDMI specification, for stunning rendering of over one billion colors in unprecedented detail.
• Broader color space: HDMI 1.3 adds support for “x.v.Color™” (which is the consumer name describing the IEC 61966-2-4 xvYCC color standard), which removes current color space limitations and enables the display of any color viewable by the human eye.
• New mini connector: With small portable devices such as HD camcorders and still cameras demanding seamless connectivity to HDTVs, HDMI 1.3 offers a new, smaller form factor connector option.
• Lip Sync: Because consumer electronics devices are using increasingly complex digital signal processing to enhance the clarity and detail of the content, synchronization of video and audio in user devices has become a greater challenge and could potentially require complex end-user adjustments. HDMI 1.3 incorporates automatic audio synching capabilities that allows devices to perform this synchronization automatically with total accuracy.
• New HD lossless audio formats: In addition to HDMI’s current ability to support high-bandwidth uncompressed digital audio and all currently-available compressed formats (such as Dolby® Digital and DTS®), HDMI 1.3 adds additional support for new lossless compressed digital audio formats Dolby TrueHD and DTS-HD Master Audio™.

Q. What is the difference between DVI and HDMI?

HDMI is DVI with the addition of:

• Audio (up to 8-channels uncompressed)
• Smaller Connector
• Support for YUV Color Space
• CEC (Consumer Electronics Control)
• CEA-861B InfoFrames

Q. Is HDMI backward compatible with DVI (Digital Visual Interface)?

Yes, HDMI is fully backward compatible with DVI compliant devices. HDMI DTVs will display video received from existing DVI-equipped products, and DVI-equipped TVs will display video from HDMI sources. However, some older PCs with DVI are designed only to support computer monitors, not televisions. Consumers buying a PC with DVI should make sure that it specifically includes support for television formats and not just computer monitors.

Also, consumers may want to confirm that the DVI interface supports High-bandwidth Digital Content Protection (HDCP), as content that requires HDCP copy protection will require that both the HDMI and DVI devices support HDCP to properly view the video content.
Source: HDMI.org

Introduction

One of the greatest advancements in the networking field in the last couple of decades has been the widespread adoption of fibre optic communication technologies. Without fibre optic cables we would not have the network speeds we see today. Likewise, we would not have a lot of the products and services that are available to us today (like YouTube, Hulu and such sites).

Let’s Begin

Fibre optics work by transmitting light signals instead of electrical signals like those found in traditional copper wire. Fibre optic cables do this by acting as a wave guide for light waves of a certain frequency. It can do this due to the scientific principle called refraction. Refraction is the change in direction of a wave (in this case a light wave) due to a change in speed. One example of this is a straw in a glass of water; it will appear that the straw is bent but in reality it is only the light waves which have been bent when they transition from air to water. Fibre optic cables work very much the same way except that the light wave’s direction is changed more drastically in a way which keeps the light wave within the core of the fibre optic cable. This is called total internal reflection and is shown in Figure 1. As you can see, the beam of red light travels from side to side as it travels from one end to the other. This is how fibre optics can transmit data across long distances while not confined to being straight line of sight paths.

Figure 1: Total internal reflection, courtesy of www.wikipedia.com

How do light waves change their speeds? They do this as they travel through different mediums. Light travels the fastest in a vacuum; this is considered the speed of light (about 300 million metres per second). In earth’s atmosphere light travels slightly slower, and through water light travels even slower. In fact, different wave lengths of light (which is the same as saying different colours of light) will change their speed at different rates. This is how rainbows are created; light waves will be refracted as they contact water droplets, and different colours will be refracted different amounts and result in the splitting up of the colours.

The fact that different colours, or wavelengths, of light will refract differently is good if you want to make rainbows; but in fibre optic cables this is bad. Fibre optic cables are manufactured with a specific refractive index (a number which indicates the properties of refraction) and are designed to be used with one wavelength of light. These wavelengths are in the infra-red spectrum and the values used are 850 nanometres (nm), 1300nm (or 1310nm, more on that later), and 1550nm. However, due to imperfect transmitter manufacturing it is in fact a small spectrum of wavelengths around the desired wavelength. Even these very small differences in wavelengths will refract differently within the fibre cable. This is called dispersion, and there are many techniques available to counter this undesirable behaviour.

Of course, some applications may not be as sensitive to these dispersion effects. This is what multi-mode fibre is for. There are basically two types of fibres. Multi-mode fibre is the type of fibre one is likely to see within a building or between a few buildings, while single mode fibre is used for long-haul communications.

Multi-mode fibre

Multi-mode fibre allows light-waves to travel along different paths within the core because it is manufactured with a larger core size. This is beneficial because it is easier to make the actual cable and it allows for more inexpensive transmitters, such as LEDs, which are not capable of the extreme precision required for single-more fibre optic cables. Transmitters for multi-mode fibre optic cables typically operate at either 850nm or 1300nm. Because of the larger core, which can collect more light easier, there is a high degree of dispersion which occurs in multi-mode fibre optic cables. This is why there is a limited range for which multi-mode fibres can be used. Multi-mode fibre optic cables are commonly seen within a building, or a small campus of buildings. If multi-mode fibre optic cable is used for longer ranges the dispersion will be seen as noise on the receiver and will significantly reduce performance.

Another, not as obvious, problem that is caused by this dispersion is the longer wait time required between pulses. Because different wavelengths refract differently, each wavelength will have a different total length traveled from transmitter to receiver. This means that a receiver will receive a pulse that is wider than the pulse originally sent by the transmitter. So, any transmitter will have to take into consideration what the pulse width will be at the receiver and leave an appropriate amount of space between pulses to compensate for this.

Another type of dispersion seen in multi-mode fibre optic cables is called modal dispersion. Basically, because light pulses can enter the core at different angles (because of the larger core) there can be a variety of paths which a pulse can take to travel to the receiver. Because of these different paths (called modes) the pulses traveling along these modes will not arrive at the receiver at the same time. This will be seen as noise by the receiver and must be compensated for. Modal dispersion is another reason why there must be a significant wait time between pulses which of course will limit the total achievable bandwidth.

Single mode fibre

Single mode fibers are typically used in long-haul communications. Single mode fibres have a smaller core and require a much more precise transmitter, which of course is considerably more expensive. Because of this smaller core a light pulse can only travel along one mode which eliminates the problem of modal dispersion. With that improvement over multi-mode fibre optic cables, single-mode fibre optic cables require less wait time between pulses and are capable of much higher transmission bandwidths.

Single-mode fibre optic cables typically operate with light wavelengths of 1310nm or 1550nm. Why 1310nm and not 1300nm like multi-mode fibre optic cables? Well this is only a convention, which I’m told, goes back to the days when AT&T was the king of fibre.

While single-mode fibre optic cables do not suffer from modal dispersion, they do suffer from the dispersion caused by different wavelengths refracting differently. Since single-mode fibre is used for long-haul communications this type of dispersion can be a significant problem. There are some very clever ways to overcome this dispersion, but they best left for another article.

Use of fibre as sensors

Most people, incorrectly, assume fibre optic cables are only used for telecommunication purposes; there are actually many other uses for fibre optic cables. While telecommunications is a very common, visible, use of fibre optics, it is also very common to use them as sensors.

Because of the various properties of light, all of which also occur within a fibre optic cable, fibre optics can be used to measure strain, temperature, or pressure. This can happen by designing a fibre optic cable to be sensitive to a specific element such as temperature, or strain. This will then affect the light pulse sent through the fibre optic cable, the change pulse received after passing through the fibre can then be analyzed to determine the amount of strain or the temperature, or whatever is being measured. This can be advantageous due to the fact that no electricity passes through the cable; in some sensitive environments this is a necessity.

source:
http://www.windowsnetworking.com/articles_tutorials/Fiber-Optics.html

Ethernet cables help to connect computing hardware devices and transmit data using the Ethernet protocol. Learn more about the types of Ethernet cable to choose the correct one for your uses.

Ethernet Cable Types

All computer devices such as a keyboard, a mouse, CPU, modem, etc. are connected using a Ethernet cable. Ethernet cables are determined and distinguished by their quality. By quality it means, the amount of transmission load the cable can handle. Following are some Ethernet cable types:

Normal Ethernet Cables
A normal Ethernet cable is a straight-through cable, where the smaller cables inside the Ethernet cable on both ends will be in the same order of colors, from left to right. There are two standards in which the colors of the cables are arranged, they are; T-568A and T-568B. The variation in their color order is not an indication of their performance, but just their standard. This type of cable is used to connect the computer to a hub or router to a switch.

Ethernet Cable Categories (Cat)
Cat 3 – This category was widely used as a voice cabling format among computer network administrators in the 1990s. It is an unshielded twisted pair (UTP), that can carry up to to 10 Mbit/s with a bandwidth performance of 16 MHz.

Cat 4 – Cat 4 was mainly used in token ring networks and the cable consists of four unshielded twisted-pair (UTP) wires, with a data rate of 16 Mbit/s, and performance of up to 20 MHz.

Cat 5 – This is a a twisted pair high signal integrity cable, that has three twists per inch of each twisted pair of 24 gouge copper wires within the cables. Cat 5 is used for 10/100Mb Ethernet and as a voice cabling format.

Cat 5e – This category is an enhanced version of Cat 5, that prevents interference between one unshielded twisted pair to another twisted pair running in parallel within the same cable (Far End Crosstalk – FEXT). It works for 10/100Mb and 1000Mb Ethernet.

Cat 6 – It is very similar to Cat 5e and is a cable standard for Gigabyte Ethernet (considered better than Cat 5e) and other network protocols that are backward compatible with the Cat 5/5e and Cat 3 cable standards. Cat 6 is made up of larger gouge wires, that work for 10/100/1000Mb Ethernet.

Cat 7 – This cable type is a standard for Ethernet and other interconnect technologies, that are backward compatible with traditional Cat 5 and Cat 6 Ethernet cables. As it has more strict specifications for crosstalk and system noise than Cat 6 and Cat 5e, its cables and the wires within are completely shielded. the cable contains four twisted copper wire pairs and supports up to 600Mhz.

Ethernet Crossover Cable
An Ethernet crossover cable is a type of Ethernet cable, that is used to connect computing devices together, without the use of a hub or switch. These cables have different pin points or plugs on each side. The wires within the Ethernet crossover cable can reverse the transmit and receive signals. Starting from the left, the 1st and 3rd wires and the 2nd and 6th wires are crossed, and can be seen through the RJ-45 connectors at each end of the crossover cable.

Ethernet cable types should be determined by your requirement, as there are many types and categories easily available all across the country. Ethernet cables are faster and take less processing from the CPU and other computer networking devices, which can save a lot of time during the transmission of data.

source: http://www.buzzle.com/articles/ethernet-cable-types.html