ANALOG ELECTRICAL and DIGITAL VIDEO FORMATS and CONNECTORS

Analog Electrical Formats/Connectors

Component Video

Component video is a type of video information that is transmitted or stored as two or more separate signals (as opposed to composite video, such as NTSC or PAL, which is a single signal).

Most component video systems are variations of the red, green and blue signals that make up a television image. The simplest type, RGB, consists of the three discrete red, green and blue signals sent down three wires. This type is commonly used in Europe through SCART connectors. Outside Europe, it is generally used for computer monitors, but rarely for TV-type applications.

Another type consists of R-Y, B-Y and Y, delivered the same way. This is the signal type that is usually meant when people talk of component video today. Y is the luminance channel, B-Y (also called U or Cb) is the blue component minus the luminance information, and R-Y (also called V or Cr) is the red component minus the luminance information. Variants of this format include YUV, YCbCr, YPbPr and YIQ.

In component systems, the synchronization pulses can either be transmitted in one or usually two separate wires, or embedded in the blanking period of one or all of the components. In computing, the common standard is for two extra wires to carry the horizontal and vertical components, whereas in video applications it is more usual to embed the sync signal in the green or Y component. The former is known as sync-on-green.

Component digital video signals are sometimes referred to as 4:2:2, meaning that for every 4 bits that are dedicated to the Y component, 2 bits each are dedicated to the U & V components on both even (second 2) and odd lines (third 2) of the image. The luminance or Y channel carries most of the image detail and is, therefore, assigned more bits. Another common method, 4:2:0, is used on DVDs. In this case, only the even lines have color information; for the odd lines it is approximated by interpolation. This signal is often converted to 4:2:2 inside the player before it is sent out to other devices.

Composite Video

Composite video is the format of an analog television signal before it is modulated onto an RF carrier. It is usually in a standard format such as NTSC, PAL or SECAM. It is a composite of three source signals called Y, U and V (together referred to as YUV) with sync pulses. Y represents the brightness or luminance of the picture and includes synchronizing pulses, so that by itself it could be displayed as a monochrome picture. U and V between them carry the colour information. They are first mixed with two orthogonal phases of a colour carrier signal to form a signal called the chrominance. Y and UV are then added together. Since Y is a baseband signal and UV has been mixed with a carrier, this addition is equivalent to frequency-division multiplexing.

Composite video can easily be directed to any broadcast channel simply by modulating the proper RF carrier frequency with it. Most home video equipment records a signal in composite format: VCRs and laserdiscs both work this way, and then give the user the option of outputting the raw signal, or mixing it with RF to appear on a selected TV channel. In the United States, the composite video signal is typically connected using an RCA jack, normally yellow (often accompanied with red and white for right and left audio channels, respectively). In Europe, this is sometimes replaced by a coax or SCART connector. BNC connectors are used for commercial variations of video media.

Some devices that connect to a TV, such as videogame consoles (and the ubiquitous home computers of the 1980s), naturally output a composite signal. This may then be converted to RF with an external box known as an RF modulator that generates the proper carrier (often for channel 3 or 4 in North America). The RF modulator is preferably left outside the console so the RF doesn't interfere with the components inside the machine. VCRs and similar devices already have to deal with RF signals in their tuners, so the modulator is located inside the box. Also, most home computers usually employed an internal RF modulator.

Yellow is the default color for composite video cables.

The process of modulating RF with the original video signal, and then demodulating the original signal again in the TV, introduces several losses into the signal. RF is also "noisy" because of all of the video and radio signals already being broadcast, so this conversion also typically adds noise or interference to the signal as well. For these reasons, it's typically best to use composite connections over RF connections if possible. Almost all modern video equipment has composite connectors, so this typically isn't a problem.

However, just as the modulation and demodulation of RF loses quality, the mixing of the various signals into the original composite signal does the same. This has led to a proliferation of systems such as S-Video and component video to separate out one or more of the mixed signals.

Composite video is often designated by the CVBS acronym, meaning either "Color, Video, Blank and Sync" or "Composite Video Baseband Signal" or "Composite Video Burst Signal" or "Composite Video with Burst and Sync".

Coaxial cable

Coaxial cable is an electrical cable consisting of a round conducting wire, surrounded by an insulating spacer, surrounded by a cylindrical conducting sheath, usually surrounded by a final insulating layer.

It is used as a high-frequency transmission line to carry a high- frequency or broadband signal. Sometimes DC power (called bias) is added to the signal to supply the equipment at the other end, as in direct broadcast satellite receivers. Because the electromagnetic field carrying the signal exists (ideally) only in the space between the inner and outer conductors, it cannot interfere with or suffer interference from external electromagnetic fields.

Coaxial cables may be rigid or flexible. Rigid types have a solid sheath, while flexible types have a braided sheath, both usually of thin copper wire. The inner insulator, also called the dielectric, has a significant effect on the cable's properties, such as its characteristic impedance and its attenuation. The dielectric may be solid or perforated with air spaces. Connections to the ends of coaxial cables are usually made with RF connectors (usually F Connectors), though other connectors are possible (BNC, etc).

Signal propagation

Open wire transmission lines have the property that the electromagnetic wave propagating down the line extends into the space surrounding the parallel wires. These lines have low loss, but also have undesirable characteristics. They cannot be bent, twisted or otherwise shaped without changing their characteristic impedance. They also cannot be run along or attached to anything conductive, as the extended fields will induce currents in the nearby conductors causing unwanted radiation and detuning of the line.

Coaxial lines solve this problem by confining the electromagnetic wave to the area inside the cable, between the center conductor and the shield. The transmission of energy in the line occurs totally through the dielectric inside the cable between the conductors. Coaxial lines can therefore be bent and twisted (subject to limits) without negative effects, and they can be strapped to conductive supports without inducing unwanted currents in them. The inner conductor can be made of braid and the outer conductor can be made of corrugated tube for greater flexibility, but this comes at the cost of increased ohmic losses and lower phase velocity. The outer conductor can also be made of (in order of increasing leakage) wound foil, woven tape, or braid.

Coaxial cables require an internal structure of an insulating (dielectric) material to maintain the spacing between the center conductor and shield. Unfortunately, all dielectrics have loss associated with them, which causes most coaxial lines to have more loss than open wire lines. Most cables have a solid dielectric; others have a foam dielectric which contains as much air as possible to reduce the losses. Foam coax will have about 15% less attenuation but can absorb moisture — especially at its many surfaces — in humid environments, increasing the loss. Stars or spokes are even better, but more expensive. Furthermore the lower dielectric constant of air allows for a greater inner diameter at the same impedance and a greater outer diameter at the same cutoff frequency, lowering ohmic losses.

Connectors

From the signal point of view, a connector can be viewed as a short, rigid cable. The connector usually has the same impedance as the related cable and probably has a similar cutoff frequency although its dielectric may be different. High-quality connectors are usually gold or rhodium plated, with lower-quality connectors using nickel or tin plating. Silver is occasionally used in some high- end connectors due to its excellent conductivity, but it usually requires extra plating of another metal since silver readily oxidizes in the presence of air. One increasing development has been the wider adoption of micro-miniature coaxial cable in the consumer electronics sector in recent years. Wire and cable companies such as Tyco, Sumitomo Electric, Hitachi Cable, Fujikura and LS Cable all manufacture these cables, which can be used in cellular phones.

Important parameters to Co-Ax

• The characteristic impedance in ohms (Ω) is calculated from the ratio of the inner and outer diameters and the dielectric constant. Assuming the dielectric properties of the material inside the cable do not vary appreciably over the operating range of the cable, this impedance is frequency independent.

• Capacitance, in farads per metre.

• Resistance, in ohms per metre.

• Attenuation or loss, in decibels per metre. This is dependent on the loss in the dielectric material filling the cable, and resistive losses in the center conductor and shield. These losses are frequency dependent, the losses becoming higher as the frequency increases. In designing a system, engineers must consider not only the loss in the actual cable itself, but also the insertion loss in the connectors.

• Outside diameter, which dictates which connectors must be used to terminate the cable.

• Velocity of propagation, which depends on the type of dielectric.

• Cutoff frequency

Standards

Most coaxial cables have a characteristic impedance of either 50, 52, 75, or 93 ohms. The RF industry uses standard type-names for coaxial cables. A series of standard types of coaxial cable were specified for military uses, in the form "RG-#" or "RG-#/U" (RG from Radio Guide, /U indicates multiple uses). They go back to World War II and were listed in MIL-HDBK-216 published in 1962. These designations are now obsolete. The current military standard is MIL- SPEC MIL-C-17. MIL-C-17 numbers, such as "M17/75-RG214," are given for military cables and manufacturer's catalog numbers for civilian applications. However, the RG-series designations were so common for generations that they are still used, although critical users should be aware that since the handbook is withdrawn there is no standard to guarantee the electrical and physical characteristics of a cable described as "RG-# type". The RG designators are mostly used to identify compatible connectors that fit the inner conductor, dielectric, and jacket dimensions of the old RG-series cables.

Significance of impedance

A question that is often asked is what the significance of a 50 or 75 ohm characteristic impedance is. The best coaxial cable impedances to use in high- power, high-voltage, and low-attenuation applications was experimentally determined in 1929 at Bell Laboratories to be 30, 60, and 77 ohms respectively. 30 ohm cable is exceedingly hard to make however, so a compromise between 30 ohms and 60 ohms was reached at 50 ohms, which has stuck. 75 ohms is just easier than 77 ohms and has also stuck as a popular impedance.

Uses

Short coaxial cables are commonly used to connect home video equipment, or in ham radio setups. They used to be common for implementing computer networks, in particular Ethernet, but twisted pair cables have replaced them in most applications.

Long distance coaxial cable is used to connect radio networks and television networks, though this has largely been superseded by other more high-tech methods (fibre optics, T1/E1, satellite). It is still common for carrying cable television signals.

Micro coaxial cables are used in a range of consumers devices, military equipment, and also in ultra-sound scanning equipment.

Types

In broadcasting and other forms of radio communication, hard line is a very heavy-duty coaxial cable, where the outside shielding is a rigid or semi-rigid pipe, rather than flexible and braided wire. Hard line is very thick, typically at least a half inch or 13 mm and up to several times that, and has low loss even at high power. It is almost always used in the connection between a transmitter on the ground and the antenna or aerial on the tower. Hard lines are often made to be pressurised with nitrogen or desiccated air, which provide an excellent dielectric even at the high temperatures generated by thousands of watts of RF power, especially during intense summer heat and sunshine. Physical separation between the inner conductor and outer shielding is maintained by spacers, usually made out of tough solid plastics like nylon.

Triaxial cable or triax is coaxial cable with a third layer of shielding, insulation and sheathing. The outer shield, which is earthed (grounded), protects the inner shield from electromagnetic interference from outside sources.

Twin-axial cable or twinax is a balanced, twisted pair within a cylindrical shield. It allows a nearly perfect differential signal which is both shielded and balanced to pass through. Multi-conductor coaxial cable is also sometimes used.

Biaxial cable or biax is a figure-8 configuration of two 50 ohm coaxial cables, used in some proprietary computer networks.

Semi-rigid cable is a coaxial form using a solid copper outer sheath. This type of coax offers superior screening compared to cables with a braided outer conductor, especially at higher frequencies. The major disadvantage is that the cable, as its name implies, is not very flexible, and is not intended to be flexed after initial forming.

Interference and troubleshooting

Despite being shielded, interference can occur on coaxial cable lines. Eventually, the insulation degrades and the cable must be replaced, especially if it has been exposed to the elements on a continuous basis. The copper screen is normally grounded, and if even a single thread touches the inner copper core, the signal will be shorted out. This most often occurs at improperly installed end connectors and splices. Also, the connector or splice must be properly attached to the copper screen, as this provides the return electrical path for the signal. Low frequency signals (below 100 MHz) can penetrate the shield while high frequency signals cannot.

For cable television it is important to use the correct type of coaxial cable. RG- 59/U should be avoided, and only RG-6/U, or in cases of severe interference, RG-6/UQ (quad-shield) used. Many consumers have purchased the cheaper RG- 59/U to use as an extension for cable television, only to find it causes severe interference. Also, unknown to most cable television customers, leakage of signals can cause interference to aircraft communications which operate on the same frequency as several cable channels. This may even be a violation of the law.

In the United States and some other countries, cable channels 2-13 share the same frequency as those from television broadcast towers. If the cable consumer is too close to a television tower and the cable company provides the same station on the like channel, interference and 'ghosting' may result. The solution is to make sure the cable signal is at the maximum allowed strength (especially if splitters are used for multiple TV sets), as this will increase the signal-to-noise level (the "noise" being the pickup of the broadcast tower). Using the more expensive quad-shield coaxial cable also helps reduce interference. Only industrial-quality cable TV amplifiers (generally not available at retail) should be used to amplify weak signals. Cheaper ones, sold at consumer electronics stores, often cause more problems than they solve.

Addendum Co-Axial cable carries both audio and video signals. Component video cables are made from types of co-axial cable.

Timeline

1884 — Coaxial cable patented in Germany by Ernst Werner von Siemens, but with no known application. [unverified: more details needed]

1894 — Oliver Lodge demonstrates waveguide transmission at the Royal Institution. Nikola Tesla receives U.S. Patent 0514167, Electrical Conductor, on February 6.

1929 — First modern coaxial cable patented by Lloyd Espenschied and Herman Affel of AT&T's Bell Telephone Laboratories, U.S. Patent 1835031.

1934 — First transmission of TV pictures on coaxial cable, from the Berlin Olympic Games to Leipzig.

1936 — AT&T installs experimental coaxial TV cable between New York and Philadelphia.

1936 — Coaxial cable laid by the Post Office (now BT) between London and Birmingham, providing 40 telephone channels. [Source: archives at http://www.bt.com]

1941 — First commercial use in USA by AT&T, between Minneapolis, Minnesota and Stevens Point, Wisconsin. L1 system with capacity of one TV channel or 480 telephone circuits.

1956 — First transatlantic coaxial cable laid, TAT-1.

S-Video

S-Video is one of the high quality methods of transmitting a television signal from a device such as a Camcorder, DVD, or a digital satellite receiver. S-video signal is also know with name Y/C-video. Sometimes you can also see name S-VHS-video used (use of this name is not recommended).In "S" video, the chroma and video are separated to eliminate noise and tocreate a higher bandwith for each. S-video (Y/C) uses two separate video signals. The luminance (Y)is the black & white portion, providing brightness information.The chrominance, or chroma (C) is the colour portion, providinghue and saturation information. Signal component separation prevents nasty things like color bleeding and dot crawl, and helps increase clarity and sharpness. S-Video is "essentially" the same as Chroma & Luma, Brightness & Color, or y/c. They all mean the same thing, in a vague sort of way. Don't get confused here if you see different names for this connection. S-Video appeared associated with the first S-VHS VCR systems.S- video was also used by small computer industry starting from late 1980s.This separate the color (c) and luminance (y) information and carry them through separate wires, a system that became known as YC and later S-Video. This made it reasonably easy to integrate into existing equipment and at the same time provide a distinct increase in picture quality. Since the color and luminance were carried in separate cables, it had the potential to eliminate both the cross color problem and the trap problem.While most equipment takes full advantage of the signal separation, not all equipment properly implements the two separate channels.S-Video has also become a popular standard for home use, especially with DVD players.Panasonic's version of S-Video (using the 4-pin mini-DIN connector) seems tobe a "de-facto" standard these days. This means that S- Video (also called Y/C or component video) is carried on cables that end in 4-pin Mini-DIN connectors (other connector can be also used like pair of BNC connector, SCART connector or 7-pin Mini-DIN on some computer graphics cards). Quite often you can see documents that compare composite video and S- video to each other. The problem with composite video vs. "S-Video" isn'tone of bandwidth loss. S-Video can provide a better imagesimply because the luminance and chrominance components ofthe TV signal (also known as "Y" and "C") are kept separateand SHOULD therefore never have a problem with mutualinterference, which results in such effects as the infamous "chromacrawl" problem. However, there is absolutely no reason to thinkthat an S-Video connection will provide a chrominance signalof greater bandwidth. It could, were such a signal available,but there's just no reason to expect that it will.

S-Video, also known as Y/C and (incorrectly) SVHS, is an analog video signal. S- Video will appear better than composite video since the TV does not have to decode the brightness and color information that are found together on composite video.

Method

The luminance (Y) signal and modulated chrominance (C) subcarrier information are carried on separate synchronized signal/ground pairs.

In composite video, the luminance signal is low-pass filtered to prevent crosstalk between high-frequency luminance information and the color subcarrier. S-Video, however, separates the two, so low-pass filtering is not necessary. This increases bandwidth for the luminance information, and also subdues the color crosstalk problem.

The luminance performance of S-Video is noticeably better than composite video; the chrominance performance with reduced crosstalk also shows noticeable improvement.

S-Video signals tend to degrade considerably when transmitted across more than 5 meters of cable with some cheaper S-Video cables.

Connector

Today, S-Video signals are generally connected using 4-pin mini-DIN connectors using a 75 ohm termination impedance. However, 7-pin mini-DIN connectors are also common. The pins in the connectors can bend easily but this is usually not a problem when properly inserting it to the s-video receptacle. If a pin is bent the result could be loss of color, corruption of the signal, or complete loss of the signal.

Before the mini-DIN plug became standard, S-Video signals were often carried through different types of plugs. For example, the Commodore 64 home computer of the 1980s, one of the first widely available devices to feature S- Video output, used an 8-pin standard size DIN plug on the computer end and a pair of RCA plugs on the monitor end. The S-Video connector is the most common video-out connector on laptop computers.

Today, S-Video signals can be transferred through SCART connections as well. However the device that has the SCART connector must support S-Video as it is not part of the original SCART standard. For instance, a VCR that has a SCART connector may not support S-Video, so if you try to connect an S-Video signal through a SCART connector you will get a black and white signal.

Usage

S-Video is commonly used on consumer TVs, DVD players, VTRs, and modern game consoles. Many computer video cards also have an S-Video output.

S-Video is also considered a component signal, because the luminance and chrominance (color) signals are transmitted on separate wires. S-Video carries only video signals, not audio.

PAL Connector: PAL series are developed for use on Phase Alternate Line TV antenna receiving Equipment. They were extremely common in Europe.

SCART Connector SCART (from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs) is a French-originated standard and associated 21-pin connector for connecting audio-visual equipment together. It is also known as Péritel (especially in France, where the SCART word is not normally used) and Euroconnector.

SCART makes it easy to connect AV equipment (including TVs, VCRs, DVD players and games consoles). In essence, it gathers together various common analog signal-types into a single connector. Previously, each of these would have had their own socket, requiring numerous separate connections (and a "spaghetti"-type mass of leads). The signals carried by SCART include both composite and RGB video, and stereo audio input/output, as well as support functions.

In Europe, SCART is the most common method of connecting audio-visual equipment together, and has become the standard connector for such devices (even more so than the phono plug). It is far less common elsewhere in the world. The official standard for SCART is CENELEC document number EN 50049-1.

Motivations and applications for SCART

Before SCART came, consumer TV sets did not offer a standardized way of inputting signals other than RF antenna ones, and even antenna connectors differed between countries. Assuming other connectors even existed, devices made by different companies could have different and incompatible standards. For example, a VHS VCR could output a composite video signal through a German-originated DIN-style connector, an American-originated RCA connector, or a BNC connector.

SCART sockets

SCART attempts to make connecting video devices together much simpler, by providing one plug that contains all the necessary signals and is standard across different manufacturers. SCART makes connecting such devices very simple, because one cable can connect any two SCART-compatible devices, and the connector is designed so that you cannot insert it incorrectly. Devices with multiple SCART connectors can pass the signals unchanged when not active, which allows daisy chaining of multiple signal sources into a single TV socket. The voltage levels are quite high, around 1V, so the signals have good noise immunity.

SCART is bi-directional regarding standard composite video and analog audio. A television set will typically send the antenna audio and video signals to the SCART sockets all the time and watch for returned signals, to display and reproduce them instead. This allows it to have "transparent" set-top boxes, without any tuner, which just "hook" and pre-process the television signals. This feature is used for analog Pay TV like Canal Plus and was in the past used for decoding teletext. A VCR will typically have 2 SCART sockets, one connecting to the television set, and another one for the set-top box. When idle or powered off, the VCR will forward the signals from the television set to the set- top decoder and send the processed result back to the television set. When a scrambled show is recorded, the VCR will drive the set-top box from its own tuner and send the unscrambled signals to the television set for viewing or simple recording control purposes. Alternatively, the VCR could use the signals from the television set, in which case it would be unadvisable to change channels on the television set during the recording.

SCART also allows to instruct the television set to very quickly switch between signals, in order to create inserts in the image. In order to implement captioning or subtitles, a SCART set-top box does not have to process and send back a complete new video signal, which would require full decoding and re-encoding of the color information, a signal-degrading and costly process, especially given the presence of different standards in Europe. The box can instead ask the television set to stop displaying the normal signal and display a signal it generates internally for selected image areas, with pixel-level granularity. This can be driven by the usage of a "transparent" color in a teletext page.

SCART allows a connected device to power on and power off a television set, more precisely: to bring it in and out of standby mode, in the same way as a remote control would do. A VCR will optimally power on when a cassette is inserted, power on the television set (or switch it to video mode) and then start playing immediately if the cassette's write protection tab is absent. When turned off, the VCR will ask the television set to power off as well, which the set will do if it was powered on by the VCR's request and if it remained in video mode all along.

The standard was extended at the end of the 1980s to support the new S-Video signals.

Drawbacks

SCART cannot carry both S-Video and RGB signals at the same time. It is, however, possible to output S-Video and RGB alternately, (for example, from an S-VHS + DVD combo player), and the TV set will adapt automatically if it understands SCART's S-Video extension. Many DVD players sold in Europe offer the ability to output either RGB or S-Video, which is either selected in the DVD player's set-up menu or by a switch on the back of the system.

SCART cannot officially carry other non-RGB type (e.g. YPbPr) component video signals, which are gaining ground as an improvement over S-Video in markets where SCART is not used. However, some manufacturers of set-top-boxes and DVD players are known to provide optional (menu-selectable), non-standard YPbPr output through the pins that are officially reserved for RGB color components. SCART is not designed to transmit digital video or audio signals. The new (digital) audio+video HDMI connector is often referred to as "digital SCART". From this it appears that there will never be a second generation analog SCART to address the above limitations.

SCART is limited to two audio channels - meaning it cannot deliver surround sound with discrete surround channels, such as Dolby Digital or DTS.

SCART connects are non-locking and are prone to falling off or getting loose, especially since the thick 21-wire cable is relatively heavy and often leaves the connector at a sideways angle. Loss of audio or video connection due to a loose SCART connector is relatively common. To allow limited locking, some connectors (such as the one portrayed on this page) have bumps on the sides. The thickness and inflexibility of the cables, combined with the fact that they are connected to the plugs at an angle, can sometimes make it difficult to connect items of equipment, especially in confined spaces. Attempts at thinner or flat cables are more susceptible to cross-talk, or are unable to support all communication modes.

The connector design requires the plug to be perfectly aligned over the socket before it can be inserted at all, whereas most other connect designs are self- correcting if the plug is inserted at slightly the wrong angle. Cheap SCART connectors can be very fragile and prone to breaking, losing pins, etc., since they are big and hollow.

SCART can sometimes be confusing for consumers. Most TV sets that have multiple SCART connectors have only one capable of receiving RGB and the other one capable of receiving S-video. Also, not all SCART cables make use of all the pins, often leaving out RGB signals. In many cases there is also no way to see which type of signal that is currently displayed on the TV set.

Practical advice The picture quality of the different signals mentioned in this article can be ranked as follows: Best: RGB Component YPbPr Component (note: not supported by SCART) S-Video Composite Worst: RF (note: not supported by SCART)

Nearly all DVD players with SCART sockets will output RGB video, which offers far superior picture quality to typical composite signals. However, many players do not have RGB output turned on by default - this often has to be set manually in the player's setup menu or via switches on the back of the player.

The Nintendo GameCube, Sony PlayStation 2 and Microsoft Xbox can output RGB, Y-Cr-Cb, S-Video, or composite video. These consoles come with the standard composite video connector, but the manufacturers and third parties sell connectors for component video hookup and for RGB SCART hookup. Where the GameCube and Xbox automatically switch to the proper mode, the Playstation 2 must be told via a selection in the system menu whether it is to use YPbPr or RGB component video. Also some versions of legacy consoles such as Nintendo's SNES and Nintendo 64 are capable of outputting RGB signals. (On SNES and N64, the same cable is used as for GameCube.)

Maximum SCART cable length is estimated to about 10 to 15 meters without relay.

Due to the high voltage used in SCART, "hot plugging" (connecting or disconnecting devices while they are on) is not recommended. Although there is no risk of personal injury, there is the possibility of damaging electronics within the devices if the connector is inserted improperly.

Quality differences exist in SCART cables. While a proper SCART cable would use miniature coax cables for the video signals, cheap SCART cables often use plain wires for all signals, resulting in a loss of image quality and greatly reducing the maximum cable length. To non-destructively verify if a SCART cable uses coax cables, one can unscrew the strain relief at the SCART connector and fold open the plastic shell. A common problem is that a TV will output a composite video signal from its internal tuner, and this will be induced or cross-talk onto an incoming video signal due to inadequate or non-existent screening on a cheap SCART cable; the results will be ghostly images or shimmering superimposed on the incoming signal.

Gold plated SCART connectors, which don't corrode and deliver a cleaner signal might be preferable, although they always cost more than Nickel ones. It should be noted, though, that gold plated connectors only give better performance when both plug and socket are gold plated. Gold and Nickel are galvanically very different metals, and although inserting a gold plated plug into a nickel plated socket may make a small difference at first, any atmospheric moisture that is present near the connector will cause an electrolytic reaction between the dissimilar metals. This will result in the nickel plated connector corroding much more rapidly than it would if both connectors were nickel plated. For good long term connection quality it is always better to use matching connector materials.

BNC

The BNC connector is a type of RF connector used for terminating coaxial cable. The connector was named after its bayonet mount locking mechanism and its two inventors, Paul Neill of Bell Labs (inventor of the N connector) and Amphenol engineer Carl Concelman (inventor of the C connector). It is a lot smaller than N and C connectors. Nicknames the BNC has picked up over the years include: "Baby Neill-Concelman", "Baby N connector", "British Naval Connector", "Bayonet Nut Connector".

The BNC connector is used for professional video connections, both for analog and Serial Digital Interface signals, amateur radio antenna connections, and on nearly every piece of electronic test equipment manufactured in the last 35 or so years. This connector is an alternative to the RCA connector when used for composite video on commercial video devices, however many consumer electronics with RCA jacks have been utilized on commercial video equipment with BNC jacks via adaptor. BNC connectors were commonly used on 10base2 thin Ethernet networks, both on cable interconnections and network cards, though these have largely been replaced by newer Ethernet devices whose wiring does not use coaxial cable. Some ARCNET networks use BNC terminated coax.

N Connector

The N connector (in full, Type N connector) is a threaded RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave- Type N connector (female) Type N connector (male) frequency signals, and was invented in the 1940s by Paul Neill of Bell Labs. Originally, the connector was designed to carry signals of up to 1 GHz in military applications, but the common Type N today handles up to 11 GHz comfortably. More recent precision enhancements to the design by Julius Botka at Hewlett Packard have scaled this to 18 GHz. The male connector is hand-tightened and has an air gap between center and outer conductors.

The N connector follows the MIL-C-39012 standard, defined by the US military, and comes in 50 and 75 ohm versions, the latter of which is used in the cable television industry.

C Connector

C connectors couple using two-stud bayonet-type locks. The C connector was invented by Amphenol engineer Carl Concelman. C connectors are medium size and weatherproof. Coupling is two-stud bayonet lock. C connectors provide constant 50 Ω impedance. They may be used with 75 Ω cable, at lower frequencies (below fg300 MHz) where no serious mismatch is introduced.

F connector

The F connector is a type of coaxial RF connector commonly used for cable television and universally for satellite television and cable modems, usually with RG-6/U cable or (in older installations) with RG-59/U cable. The F connector is inexpensive, yet has good 75-ohm impedance match up to 1 GHz. One reason for its low cost is that it uses the center wire of the coaxial cable as the pin of the male connector. While lowering cost, this design drastically reduces the long- term reliability compared to other connectors, the copper wire being extremely prone to corrosion. The male connector body is typically crimped, or sometimes screwed, onto the exposed outer braid. Female connectors have a 3/8-32 thread. Most male connectors have a matching threaded connecting ring, though push-on versions are also available. Push-on F connector ends provide poor shielding against airborne signals (for example, a nearby TV transmitter will interfere with a CATV station).

UHF connector

The UHF connector is a pre-World War II threaded RF connector design, from an era when UHF referred to frequencies over 30 MHz. UHF connectors are generally usable through what is now know as the VHF frequencies and can handle RF power levels over one kilowatt. PL-259 plug. 18 mm.

The most popular cable plug and chassis-mount socket carry the U.S. military nomenclatures PL-259 and SO-239, respectively. The PL-259 can be used with large diameter coaxial cable, such as RG-8/U and RG-9/U, and the smaller diameter RG-58/U and RG-59/U with an adapter sleeve. Technically, "PL-259" refers to one specific mechanical design, but the term is often used for any UHF cable plug. The center conductor jack on the SO-239 will also accept a banana plug.

UHF connectors were replaced in many applications by designs that have a more uniform impedance over the length of the connector, such as the N connector and the BNC connector, but they are still widely used in amateur radio, citizens' band radio, and marine VHF radio.

MHV Connectors

MHV connectors are compact, 50-ohm impedance, high-voltage connectors with two-stud bayonet coupling. MHV connectors are similar in size to, but are not intermateable with, BNC connectors.

They are best suited for use with cables in the range of .195" to .220" diameter, but are available for other cables from .090" to over .75" diameter.

For safety, Delta MHV connectors feature deeply recessed contacts, as well as polarized plugs and jacks to ensure that only the compatible plugs and jacks can be mated in applications incorporating multiple connector pairs.

SHV Connectors

SHV - Safe High Voltage connectors provide more secure handling due to well-recessed center contacts. This prevents shock hazards in unmated condition. All inner contacts are fully captivated and will withstand axial forces of 100 N minimum. When mating a connector pair, the outer conductor contact is made prior to the inner conductor contacts.

SHV connectors are suitable for all high voltage applications up to 5 kV DC or 3.5 kV rms. These connectors are typically used in nuclear instruments or Test+Measurement equipment. Voltages are valid for both mated and unmated conditions.

RF Carrier

An RF (for radio frequency.) AM technique wherein a carrier, with a frequency much higher than the encoded information, varies according to the amplitude of the information being encoded.

Radio frequency (abbreviated RF, rf, or r.f.) is a term that refers to alternating current (AC) having characteristics such that, if the current is input to an antenna, an electromagnetic (EM) field is generated suitable for wireless broadcasting and/or communications. These frequencies cover a significant portion of the electromagnetic radiation spectrum, extending from nine kilohertz (9 kHz), the lowest allocated wireless communications frequency (it's within the range of human hearing), to thousands of gigahertz (GHz).

When an RF current is supplied to an antenna, it gives rise to an electromagnetic field that propagates through space. This field is sometimes called an RF field; in less technical jargon it is a "radio wave." Any RF field has a wavelength that is inversely proportional to the frequency. In the atmosphere or in outer space, if f is the frequency in megahertz and s is the wavelength in meters, then s = 300/f

The frequency of an RF signal is inversely proportional to the wavelength of the EM field to which it corresponds. At 9 kHz, the free-space wavelength is approximately 33 kilometers (km) or 21 miles (mi). At the highest radio frequencies, the EM wavelengths measure approximately one millimeter (1 mm). As the frequency is increased beyond that of the RF spectrum, EM energy takes the form of infrared (IR), visible, ultraviolet (UV), X rays, and gamma rays.

Many types of wireless devices make use of RF fields. Cordless and cellular telephone, radio and television broadcast stations, satellite communications systems, and two-way radio services all operate in the RF spectrum. Some wireless devices operate at IR or visible-light frequencies, whose electromagnetic wavelengths are shorter than those of RF fields. Examples include most television-set remote-control boxes, some cordless computer keyboards and mice, and a few wireless hi-fi stereo headsets.

The RF spectrum is divided into several ranges, or bands. With the exception of the lowest-frequency segment, each band represents an increase of frequency corresponding to an order of magnitude (power of 10). The table depicts the eight bands in the RF spectrum, showing frequency and bandwidth ranges. The SHF and EHF bands are often referred to as the microwave spectrum.

Designation Abbreviation Frequencies Free-space Wavelengths Very Low VLF 9 kHz - 30 kHz 33 km - 10 km Frequency Low LF 30 kHz – 300 kHz 10 km – 1 km Frequency Medium MF 300khz – 3 MHz 1km – 100m Frequency High HF 3 MHz – 30 MHz 100 m – 10 m Frequency Very High VHF 30 MHz - 300 MHz 10m – 1 m Frequency Ultra High UHF 300 Mhz – 3 GHz 1 m - 100 mm Frequency Super High SHF 3GHz – 30 GHz 100 mm - 10 mm Frequency Extremely High EHF 30 GHz – 300 GHz 10mm – 1mm Frequency

DIGITAL SIGNAL FORMATS/CONNECTORS

Firewire / IEEE 1394

IEEE 1394 is a fast (up to 400 Mbit/s) serial bus interface. IEEE 1394 was called Firewire before standardization in IEEE to become standard IEEE 1394. Firewire, or IEEE- 1394, is that tiny, square-like connector tucked away on the side of your digital camcorder that allows you to upload DV format to your computer, among other things.

IEEE 1394 is nowadays used mainly for interconnecting modern digital video equipments to PCs/Macs. For example practically every DV camera has IEEE 1394 interface in it, so with IEEE 1394 interface card and suitable software you can transfer your movies form DV camera to a PC hard disk for editing.

The DV (Digital Video) recording standard now driving most consumer camcorder purchases, is a serial digital format of 25 Mbps, sometimes called DV25. The Firewire (IEEE 1394) interface conveniently handles the data rate of DV, and then some. The DV format is the first application making tremendous use of the IEEE 1394 capability. IEEE 1394 is also designed be become on universal digital inteface between digital consumer video equipment like DV cameras, DVD players and digital flat panel displays.

Devices on the IEE 1394 bus are Hot-Swappable, which means that the bus allows live connection/disconnection of devices. The digital interface supports either asynchronous and isochronous data transfers. Addressing is used to a particular device on the bus. Each device determines its own address.

IEEE 1394 supports up to 63 devices at a maximum cable distance between devices of 4.5 meters. However, "powered" Firewire devices and repeaters will repeat a signal and allow you to extend another 15 feet. The maximum devices on the bus is 16 allowing a total maximum cable distance of 72 meters. The 1394 specification limits cable length to 4.5 meters in order to satisfy the round trip time maximum required by the arbitration protocol. Some applications may run longer lengths when the data rate is lowered to the 100 Mbps level.

The 1394 system utilizes two shielded twisted pairs and two single wires. The twisted pairs handle differential data and strobe (assists in clock regeneration) while the separate wires provide power and ground for remote devices needing power support. Signal level is 265 mV differential into 110 ohms. The 1394 specification provides electrical performance requirements, which leave open the actual parameters of the cable design. As with all differential signaling systems, pair-to-pair data skew is critical (less than 0.40 nanoseconds). Crosstalk must be maintained below -26 dB from 1 to 500 MHz. The only requirement on the size of wire used is that velocity of propagation must not exceed 5.05 nS/meter. The typical cable has 28 gauge copper twisted pairs and 22 gauge wires for power and ground.

A Firewire connected appliance may or may not need power from its host, but must be capable of providing limited power for downstream devices. The 1394 specification supports two plug configurations: a four-pin version and a six-pin version. Six-pin versions can carry all six connections and are capable of providing power to appliances that need it. For independently powered appliances, like camcorders, the four-pin version is used for its compactness. Cable assemblies have the data signal pairs crossed over to avoid polarity issues. All 1394 type appliances have receptacles, which makes for easy upstream-downstream connection with the male-to-male cable. New standard version have increased the avaialble media from original short "Firewire" cable to other medias also. Transmitting data over CAT5 cable allows data at 100Mbps to travel 100m (specified in IEEE 1394b). Fiber cable will allow 100 meter distances at any speed (maximum speed depends on the type of fiber cable).

SDI

SDI stands for Serial Digital Interface. The Serial Digital Interface-SDI (SMPTE 259M) grew out of the need for longer distance connection of component digital television equipment, the result being the viability of a truly digital broadcast station. SDI is capable of running hundreds of feet and can run thousands of feet if properly distributed. To understand SDI you must understand some history of digital video interfaces. The impetus for serial digital coding and transmission of video heightened with the introduction of the first component digital production video tape recorder in the mid-'80s, known as D1 or CCIR 601. Digital component recording began in 1987 with the creation of the D1 format (SMPTE 125M). The D1 interface is an 8/10 bit parallel system intended for close-in connection between digital tape recorders (19 mm tape). Its interface cabling is short due to the difficulty in maintaining proper bit timing over a byte-wide data channel. Reformatting the byte-wide D1 data via a serializer yields a very high- speed serial data stream. Serializing a 10-bit data word results in a data rate ten times faster. The 27 MHz D1 data becomes serial data at 270 megabits per second for standard component NTSC. Although SDI bit rates are very high, distribution of serial data as a single cable connection presents significant advantages. First, it's much easier (read cheaper) to route and switch one cable than a parallel system of cables. Having all data bits organized as one stream means there will be no issues with clock and data synchronization. Managing bit timing and cable equalization is easier. Data skew problems encountered with multi-conductor cables do not exist.SDI format utilizes a differential signaling technique and NRZI (non-return to zero inverted) coding. Although SDI is transmitted as an unbalanced signal on 75-ohm coax, transmission and reception involves differential amplifiers that format and detect, respectively, both data phases. Utilizing differential reception creates additional headroom and robustness in signal-to-noise performance. SDI is very immune to extraneous noise and low frequency components (hum) because the receiver takes one phase of the data transmission, inverts it, and then adds it to the in-phase portion. Like a regular analog differential amplifier, common mode noise induced into the signal is cancelled out during this inversion and addition operation.SMPTE 259M supports four SDI transmission rates and SMPTE 292M supports 1.485 Gbps for HD SDI.Currently, most serial digital application situations involve standard definition television, and here serial digital component format are the most often used. Component serial digital (4:2:2 digital component PALo or NTSC) requires 270 megabits per second. The SDI encoding algorithm ensures enough signal transitions to embed the clock within the data and minimize any DC component. SDI coaxial cable drivers AC-couple the serial data into the transmission cable, thus providing DC isolation between source and receiver. The cable loss is a serious issue on those high data rated.Well- designed receivers, called Class A type, can recover serial digital data as low as -30 dB at one-half the clock rate from a pristine source, or about 25 millivolts. The one-half clock rate frequency is used to calculate SDI cable loss. For 270 Mbps component SDI, the rate would be 135 MHz. Cable loss specifications for standard SDI, SDTI, and uncompressed SDTV are addressed in SMPTE 259M and ITU-R BT.601. In these standards, the maximum recommended cable length equals 30 dB loss at one-half the clock frequency. This high serial digital signal loss level is acceptable due to the serial digital receiver. Serial digital receivers have special signal recovery processing. SMPTE 259M mentions a typical range of expected SDI receiver sensitivity between 20dB and 30dB at one-half the data clock frequency. Like analog signals, SDI data can be corrupted with improper termination or routing that results in cable reflections. Maintaining a clean distribution path with SDI means that decoding will largely be a function of the decoder sensitivity on the receiving end. Assuming that bit transitions are recognizable, the decoder will only be limited by its peak-to-peak sensitivity. For HD SDI running at 1.5 Gbps, SMPTE 292M governs cable loss calculations. In that standard, maximum cable length equals 20dB loss at one-half the clock frequency. Due to the data coding scheme, the bit rate is effectively the same as the clock frequency in MHz. Recall that digital systems do not perform linearly to cable losses. The system performance depends on the cable loss and on the receiver performance. The economy of distributing SDI and HD SDI lies in the ability of the serial digital receiver to recover a low-level signal. In all cases, your system must operate solidly before the "cliff region" where sudden signal dropout occurs. Recommendations among cable manufacturers will certainly vary, but it is good practice to limit your run lengths to no more than 90% of the calculated value. This provides leeway for cable variations, connector loss, patching equipment, etc. Here is information on some SDI signal versions:

* SMPTE 259 Level A: 143 Mbps clock, NTSC 4fsc Composite signal, timing/alignment jitter 1.40 nS * SMPTE 259 Level B: 177 Mbps clock, PAL 4fsc Composite signal, timing/alignment jitter 1.13 nS * SMPTE 259 Level C: 270 Mbps clock, 525/625 line Component signal, timing/alignment jitter 0.74 nS * SMPTE 259 Level D: 360 Mbps clock, 525/625 line Component signal, timing/alignment jitter 0.56 nS * SMPTE 292: 1485 Mbps clock, HDTV signal, timing jitter 0.67 nS, alignment jitter 0.13 nS All those system use 800 mV (peak-to-peak) signal level with 0V +-0.5V DC offset. The rise/fall times on SMPTE 259 specification are 0.40-1.50 nS range and rise/fall tiem differential is limited to 0.5 nS. In SMPTE 292 the rise/fall time is limited to be maximum 0.27 nS.Allowed overshoot is maximum 10%.

SDI is standardized in ITU-R 656, is a digitized video format used for broadcast grade video. It typically uses 75 Ohm BNC coaxial cables (which makes it easily upgradeable from analog video setups, which use the same cables). Using equalisation at the receiver, it is pobbible to send SDI over 300 metres, but shorter lengths are preferred.

Uncompressed digital component signals are transmitted. The SDI signal is self- synchronizing, uses 8 bit or 10 bit data words, and has a data rate of 270 Mbit/s.

The SDI signal starts with a Timing Reference Signal (TRS) which is a 4 word sequence which contains the unique bit pattern 3FF, 000, 000. The last word is called the Timing Reference Word (TRW), which contains information such as start/end of active video, and the current field. The last digits of the last word are a Hamming Code to protect the TRW. A Hamming Code is a error recovery code, meaning that if any of the bits of the TRW are corrupted, the Hamming code can be used to detect the error and recover the data.

The order of the data samples sent down the line is Cb, Y, Cr, Y, and 720 Luminance samples are taken across a line of video data, with 360 Cb and 360 Cr samples (also known as YUV 4:2:2). These samples can be at either 8 or 10 bit depth. See Component Video for definitions of Cb & Cr.

The luminance samples may take any value between 64 (black) and 940 (white), and the Cb and Cr samples may take values between 64 and 960. Since the Cb & Cr samples can take positive or negative values, the zero value is 448. These values are true for 10-bit SDI, for 8-bit, simply divide the values by 4.

A SDI signal may also contain up to four embedded AES/EBU 48kHz, 16bit audio channels along with the video. These are placed in the (horizontal) blanking periods, when the SDI signal carries nothing useful, since the receiver generates its own blanking signals from the TRS.

There is an expanded specification called SDTI (Serial Digital Transport Interface), which allows compressed (i.e. DV, MPEG and others) video streams to be transported over a SDI line. This allows for multiple video streams in one cable or faster-than-realtime (2x, 4x,...) video transmission.

SDTI

Serial Data Transport Interface (SDTI) is the standard for transporting audio, video and data between professional and broadcast video devices, like cameras, VTRs, editing systems, video servers and transmitters. SDTI builds on the SDI standard that is now widely used to transfer uncompressed digital video between video devices. SDTI can transport compressed video in the same infrastructure. That will reduce decompression/compression generations during the production process and allow for faster-than-real-time video transfers. SDTI saves time and maximizes video quality.

Computer cards are starting to become available to build cost-effective, computer-based systems implementing SDTI.

Whereas the serial digital interface is designed for transfer of 4:2:2 digital component or NTSC video, the serial digital transport interface (SDTI) utilizes the SDI data format for the transport of other types of digital data. In particular, it is great for transporting compressed SDTV and HDTV throughout a television plant. Any data capable of fitting within the data transport structure (270 Mbps or 360 Mbps) of the standard may be routed via existing SDI equipment. This presents a significant advantage for most television production facilities. It also provides for "faster than real-time" data transfers between SDI devices.

DVI Connector

The Digital Visual Interface (DVI) is a video interface standard designed to maximize the visual quality of digital display devices such as flat panel LCD computer displays and digital projectors. It was developed by an industry consortium, the Digital Display Working Group (DDWG).

Overview

The DVI interface uses a digital protocol in which the desired brightness of pixels is transmitted as binary data. When the display is driven at its native resolution, all it has to do is read each number and apply that brightness to the appropriate pixel. In this way, each pixel in the output buffer of the source device corresponds directly to one pixel in the display device, whereas with an analog signal the appearance of each pixel may be affected by its adjacent pixels as well as by electrical noise and other forms of analog distortion. Previous standards such as the analog VGA were designed for CRT-based devices and thus did not use discrete time. As the analog source transmits each horizontal line of the image, it varies its output voltage to represent the desired brightness. In a CRT device, this is used to vary the intensity of the scanning beam as it moves across the screen. However, when using digital displays (such as LCD) with analog signals (such as VGA), there is an array of discrete pixels and a single brightness value must be chosen for each. The decoder does this by sampling the voltage of the input signal at regular intervals. When the source is also a digital device (such as a computer), this can lead to distortion if the samples are not taken at the center of each pixel, and there are also problems with crosstalk Technical discussion

The data format used by DVI is based on the PanelLink serial format devised by the semiconductor manufacturer Silicon Image Inc. This uses Transition Minimized Differential Signaling (TMDS). A single DVI link consists of four twisted pairs of wire (red, green, blue, and clock) to transmit 24 bits per pixel. The timing of the signal almost exactly matches that of an analog video signal. The picture is transmitted line by line with blanking intervals between each line and each frame, and without packetization. No compression is used and DVI has no provision for only transmitting changed parts of the image. This means the whole frame is constantly re-transmitted.

With a single DVI link, the largest resolution possible at 60Hz is 2.6 megapixels. The DVI connector therefore has provision for a second link, containing another set of red, green, and blue twisted pairs. When more bandwidth is required than is possible with a single link, the second link is enabled, and alternate pixels may be transmitted on each. The DVI specification mandates a fixed single link cutoff point of 165 MHz, where all display modes that require less than this must use single link mode, and all those that require more must switch to dual link mode. When both links are in use, the pixel rate on each may exceed 165 MHz. The second link can also be used when more than 24 bits per pixel is required, in which case it carries the least significant bits.

Like modern analog VGA connectors, the DVI connector includes pins for the display data channel, version 2 (DDC 2) that allows the graphics adapter to read the monitor's extended display identification data (EDID).

Connector

The DVI connector usually contains pins to pass the DVI-native digital video signals. In the case of dual-link systems, additional pins are provided for the second set of data signals.

The DVI connector may also incorporate pins to pass through the legacy analog signals using the VGA standard. This feature was included in order to make DVI universal, as it allows either type of monitor (analog or digital) to be operated from the same connector.

The DVI connector on a device is therefore given one of three names, depending on which signals it implements:

DVI-D (digital only) DVI-A (analog only) DVI-I (digital & analog)

DVI connector pins (view of plug)

The connector also includes provision for a second data link for high resolution displays, though many devices do not implement this. In those that do, the connector is sometimes referred to as DVI-DL (dual link).

DVI is the only widespread standard that includes analog and digital transmission options in the same connector. Competing standards are exclusively digital: these include a system using low-voltage differential signalling (LVDS), known by its proprietary names FPD (for Flat-Panel Display) Link and FLATLINK; and its successors, the LVDS Display Interface (LDI) and OpenLDI.

One oversight in DVI is that USB signals were not incorporated into the connector. This has been addressed in the VESA M1- DA connector used by InFocus on their projector systems, and in the now-defunct Apple Display Connector used by Apple Computer. The VESA M1 connector is essentially the VESA Plug & Display (P&D) connector, which was itself originally named the Enhanced Video Connector (EVC). The pinout of the Apple Display Connector is electrically compatible with the VESA P&D/M1, but physically the shell of the connector is a different shape.

Some new DVD players, TV sets (including HDTV sets) and video projectors have DVI/HDCP connectors; these are physically the same as DVI connectors but transmit an encrypted signal using the HDCP protocol for copyright protection. Computers with DVI video connectors can use many DVI-equipped HDTV sets as a display.

Specifications Digital Minimum clock frequency: 21.76 MHz Maximum clock frequency in single link mode: Capped at 165 MHz (3.7 Gbit/s) Maximum clock frequency in dual link mode: Limited only by cable quality (more than 7.4 Gbit/s) Pixels per clock cycle: 1 (single link) or 2 (dual link) Bits per pixel: 24 Example display modes (single link): HDTV (1920 # 1080) @ 60 Hz with 5% LCD blanking (131 MHz) UXGA (1600 # 1200) @ 60 Hz with GTF blanking (161 MHz) WUXGA (1920 # 1200) @ 60 Hz (154 MHz) SXGA (1280 # 1024) @ 85 Hz with GTF blanking (159 MHz) Example display modes (dual link): QXGA (2048 # 1536) @ 75 Hz with GTF blanking (2#170 MHz) HDTV (1920 # 1080) @ 85 Hz with GTF blanking (2#126 MHz) WQXGA (2560 # 1600) pixels (30" LCD) WQUXGA (3840 # 2400) @ 41 Hz GTF (Generalized Timing Formula) is a VESA standard. Analog RGB bandwidth: 400 MHz at $3 dB

Connector Pin numbers (looking at socket):

HDMI Connector The High-Definition Multimedia Interface (HDMI) is an industry-supported, uncompressed, all- digital audio/video interface. HDMI provides an interface between any compatible digital audio/video source, such as a set- top box, a DVD player, or an A/V receiver and a compatible digital audio and/or video monitor, such as a digital television (DTV). HDMI supports standard, enhanced, or high-definition video, plus multi- channel digital audio on a single cable. It is independent of the various DTV standards such as ATSC, and DVB(-T,-S,-C), as these are encapsulations of the MPEG data streams, which are passed off to a decoder, and output as uncompressed video data, which can be high-definition. This video data is then encoded into TMDS for transmission digitally over HDMI. HDMI also includes support for 8-channel uncompressed digital audio. Beginning with version 1.2, HDMI now supports up to 8 channels of one-bit audio. One-bit audio is what is used on Super Audio CDs.

The HDMI 1.3 standard was released on 22 June 2006 and as of that date is projected to be available in consumer products by the end of 2006. HDMI 1.3 is necessary in order to output the full bitrate of the new audio formats used on HD DVDs and Blu-ray Discs. The spec also covers a new mini connector for devices such as camcorders.

The standard Type A HDMI connector has 19 pins, and a higher resolution version called Type B, has been defined, although it is not yet in common use. Type B has 29 pins, allowing it to carry an expanded video channel for use with high-resolution displays. Type-B is designed to support resolutions higher than 1080p.

Type A HDMI is backward-compatible with the single-link Digital Visual Interface (DVI-D) used on modern computer monitors and graphics cards. This means that a DVI source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable, but the audio and remote control features of HDMI will not be available. Additionally, without support for High- Bandwidth Digital Content Protection (HDCP) on both ends, the video quality and resolution may be artificially downgraded by the signal source to prevent the end user from viewing or especially copying restricted content. (While nearly all HDMI connections support HDCP, many DVI connections do not.) Type B HDMI is similarly backward-compatible with dual-link DVI.

The HDMI Founders include consumer electronics manufacturers Hitachi, Matsushita Electric Industrial (Panasonic/National/Quasar), Philips, Sony, Thomson (RCA), Toshiba, and Silicon Image. Digital Content Protection, LLC (a subsidiary of Intel) is providing HDCP for HDMI. In addition, HDMI has the support of major motion picture producers Fox, Universal, Warner Bros., and Disney, and system operators DirecTV and EchoStar (Dish Network) as well as CableLabs and Samsung. Specifications

TMDS channel

• Carries audio, video and auxiliary data. • Signalling method: According to DVI 1.0 spec. Single-link (Type A HDMI) or dual-link (Type B HDMI).

• Video pixel rate: 25 MHz to 165 MHz (Type A) or to 330 MHz (Type B). Video formats with rates below 25 MHz (e.g. 13.5 MHz for 480i/NTSC) transmitted using a pixel-repetition scheme. Up to 24 bits per pixel can be transferred, regardless of rate. Supports 1080p60[1].

• Pixel encodings: RGB 4:4:4, YCbCr 4:4:4 (8 bits per component); YCbCr 4:2:2 (12 bits per component)

• Audio sample rates: 32 kHz, 44.1 kHz, 48 kHz, 88.2 kHz, 96kHz, 176.4 kHz, 192 kHz.

• Audio channels: up to 8. DDC channel

• Allows source to interrogate capabilities of destination device.

• I²C signalling with 100 kHz clock. • E-EDID data structure according to EIA/CEA-861B and VESA Enhanced EDID (V1.3).

Consumer Electronics Control (CEC) channel (optional)

• Uses the industry standard AV Link protocol

• Used for remote control functions. • One-wire bidirectional serial bus.

• Defined in HDMI Specification 1.0. Content Protection

• According to High-bandwith Digital Content Protection (HDCP) Specification 1.10. Connector Pin numbers (looking at socket):

Distance limitations A reported problem with HDMI is the maximum cable length. As with all cables, signal attenuation becomes too high at a certain length. For the standard HDMI copper cables at 28 AWG, some users have found signal performance degrades above a cable length of about 5 meters. For front projection televisions and computer hookups, this can result in lost data and the video device compensating in unacceptable ways. The HDMI Web site, however, disputes the 5 meter limit. "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. Cable manufacturers are expected to sell reasonably priced copper cables at lengths of up to 15 meters." (from the HDMI FAQ page) One reported way to increase the distance limit is to increase the thickness of the copper cables, effectively decreasing impedance. 24 AWG wire is considered superior to 28 AWG. Another way is to use fiber optic or dual Cat- 5 cables instead of standard copper. Some companies also offer amplifiers and repeaters that can string several HDMI cables together.