National Television System Committee (NTSC)
What is NTSC ?
NTSC is known as the National Television System Committee, it is based on analog television system which is used in most of North America, and most of South America ( except Argentina , Uruguay , and French Guiana ) , Burma , South Korea, Taiwan , Japan , Philippines, and Pacific island nations and territories.
Most of the countries are using the NTSC standard, as well as those using other analog television standards, are switching to newer digital television standards soon, of which at least four different ones are in use around the globe. But North America , a parts of Central America, and South Korea are adopting the ATSC standards known as Advanced Television Systems Committee, while other countries in the world are adopting or have adopted other standards such as PAL( Phase Alternating Line )and SECAM ( Sequential Colour and Memory ).
The first NTSC standard was developed in 1941 and had no provision for the colour television. In 1953 a second modified version of the NTSC standard is created and adopted, which is allowed colour television broadcasting compatible with the existing stock of the black-and-white receivers. NTSC was the first widely adopted broadcast colour system. After nearly 70 years of usage, the vast majority of over-the-air NTSC transmissions in the United States were replaced with the digital ATSC on June 12, 2009 and August 31, 2011 in Canada and most other NTSC markets. Despite the shift to digital broadcasting, standard definition television in these countries continue to follow the NTSC standard in the terms of frame rate and the number of lines of resolution it provided. In the United States a small number of short-range local and TV relay on station continue to broadcast NTSC , as the FCC allows it. NTSC baseband video signals are also still often used in the video playback ( typically of recordings from existing libraries using existing equipment ) and in CCTV is known as ( Closed Circuit Television ) and surveillance video systems
Background of NTSC.
The National Television System Committee was established in 1940 by the United States Federal Communications Commission ( FCC ) to resolve the conflicts that arose between companies over the introduction of a nationwide analog television system in the United States . In March 1941, the committee issued a technical standard for the black-and-white television that built upon a 1936 recommendation made by the Radio Manufacturers Association ( RMA). Technical advancements of the vestigial sideband technique allowed for the opportunity to increase and improve the image resolution. The NTSC selected 525 scan lines as a compromise between RCA's 441-scan line standard and Philco's and DuMont's desire to increase the number of scan lines to between 605 to 800. The standard recommended a frame rate of 30 frames per second, consisting of two interlaced fields per frame at 262.6 lines per field and 60 fields per second. Others standards in the final recommendation were an aspect ration of 4:3 and frequency modulation ( FM ) for the sound signal.
In January 1950 , the committee was reconstituted to standardize colour television. In December 1953, it unanimously approved what is now called the NTSC colour television standard. The " compatible colour " standard retained full backward compatibility with existing black-and-white television sets. Colour information was added to the black-and-white image by adding a colour subcarrier of 4.5 X 455/572 = 315/88 MHz to the video signal. To reduce the visibility of interference between the chrominance signal and FM sound carrier required a slight reduction of the frame rate from 30 frames per second to 30/1.001 ( approximately 29.97 ) frames per second , and changing the line frequency from 15,750 Hz to 15,750/1.001 Hz ( approximately 15,734.26 Hz ).
The first colour NTSC television camera was the RCA TK-40, used for the experimental broadcasts in 1953, an improved version , the TK-40A, introduced in March 1954, was the first commercially available colour television camera. Later that year, the improved TK-41 became the standard camera used throughout much of the 1960s. The NTSC standard has been adopted by others countries, including most of the Americas and Japan. With the advent of digital televisions, analog broadcasts are being phased out. Most of U.S NTSC broadcasters were required by the FCC to shut down their analog transmitters in 2009.An analog cut-off date for those stations was not set at all.
NTSC CHANNEL
World map of NTSC,SECAM and PAL
Feedbacks of NTSC
Actually PAL has the advantage. With NTSC, controlling tint has been a significant issue from station to station and from program to program. Tint is a function of the phase of the colour subcarrier and can vary due to a number of electrical and environmental issues. Fortunately stations have tightened their standards, and set manufacturers have improved phase control.
Europe
's PAL (Phase Alternating Line) removed the problem by reversing the phase with successive scan lines; only when the phase is equal & opposite is the colour correct. PAL sets can easily maintain correct phase relationship no matter how degraded the signal strength or phase. Therefore, the colour is always correct.
p.s. NTSC means National Television Standards Committee. In the early days many said it stood for Never Twice the Same Colour.
A frame rate of 30fps in NTSC and 25 in pal. The pal signal is most suited to countries that have a hilly terrain, as TV signals are produced in a direct line of sight + or - as opposed to radio sigs that are bounced off the ionosphere. In practice NTSC is able to give produce nice 'pastel' shades of colour. There is no benefit in buying a televisions from one country and than going to another country. It will not work. NTSC is a U.S. standard for televisions. Same goes for blue ray disc player and movies, it is region one. This is to prevent coping of movies.
NTSC is performed well in the USA, and it also provide some powerful speed in many of the games are run quickly and faster in the NTSC mode but if the they were from the originally PAL, unfortunately it causes Glitches on the games which you are playing with.
NTSC Systems Television Measurements
To characterize television system performance, an understanding of signal distortions and measurement methods as well as proper instrumentation is needed. This booklet provides information on television test and measurement practices and serves as a comprehensive reference on methods of quantifying signal distortions. This publication deals with NTSC composite analog signals. Analog component, digital composite and component, and HDTV measurements are outside its scope.
New instruments, test signals, and measurement procedures are introduced as television test and measurement technology evolves. This booklet encompasses both traditional measurement techniques and newer methods. After a discussion of good measurement practices, five general categories of television measurements are addressed:
- Video Amplitude and Time Measurements
- Linear Distortions
- Nonlinear Distortions
- Noise Measurement
- Transmitter Measurements
A basic knowledge of video is assumed and a glossary of commonly used terms is included as a refresher and to introduce new concepts. This booklet does not provide detailed instructions on how to use particular instruments. The basics of waveform monitor and vector scope operation are assumed. Consult the instrument manuals for specific operating instructions.
Reference for NTSC:
PAL (Phase Alternating Line)
Phase Alternation Line (PAL) is the analog television display standard that is used in Europe and certain other parts of the world. PAL is one of the three major TV standards together with the American National Television Systems Committee(NTSC) color television system and the French Sequential Couleur avec Memoire (SECAM). NTSC is also used in Japan. SECAM is used in countries of the former Soviet Union.
Like SECAM, PAL scans the cathode ray tube (CRT) horizontally 625 times to form the video image. NTSC scans 525 lines. Color definitions between the systems vary slightly.
PAL is used in this following countries:
Afghanistan
Algeria
Argentina (N)
Austria
Australia
Bangladesh
Belgium
Brazil (M)
China
Denmark
Finland
Germany
Hong Kong
Iceland
India
Indonesia
Iraq
Ireland
Israel
Italy
Jordan
Kenya
Kuwait
Liberia
Malaysia
Netherlands
Nigeria
Norway
New Guinea
Pakistan
Singapore
South Africa
South W. Africa
Sudan
Sweden
Switzerland
Thailand
Turkey
Uganda
United Kingdom
United Arab Emirates
Yugoslavia
Zambia
The differences between NTSC and PAL
The differences between NTSC and PAL are the reason why video tapes from Europe may not play in VHS players in the United States and vice versa.
Comparison chart
| 15.734 kHz | 15.625 kHz |
| 60 Hz | 50 Hz |
| 3.579545 MHz | 4.433618 MHz |
| 4.2 MHz | 5.0 MHz |
| 4.5 MHz | 5.5 MHz |
| 6 MHz | 7 or 8 MHz |
| 525/60 | 625/50 |
SECAM (Sequential colour with Memory)
Work on SECAM began in 1956. The technology was ready by the end of the fifties, but this was too soon for a wide introduction. Initially, a version of SECAM for the French 819-line television standard was devised and tested, but not introduced. Following a pan-European agreement to introduce colour TV only in 625 lines, France had to start the conversion by switching over to a 625-line television standard, which happened at the beginning of the 1960s with the introduction of a second network. The first proposed system was called SECAM I in 1961, followed by other studies to improve compatibility and image quality. These improvements were called SECAM II and SECAM III with the later being presented at the 1965 CCIR General Assembly in Vienna. Further improvements were SECAM III A followed by SECAM III B, the adopted system for general usage in 1967.
SECAM is sequential colour with memory. SECAM (Sequential Color Memory) is used sparingly around the world and can be found in France, parts of Greece, Eastern Europe, Russia, Africa and a few other parts of the world. However, any SECAM country can display PAL tapes in full color, but not all PAL countries can display all SECAM tapes in color. Only if they are true SECAM and not MESECAM can those VCR's display SECAM.
SECAM is a standard which permits existing monochrome television receivers predating its introduction to continue to be operated as monochrome televisions. Because of this compatibility requirement, color standards added a second signal to the basic monochrome signal, which carries the color information. The color information is called chrominance or C for short, while the black and white information is called the luminance or Y for short. Monochrome television receivers only display the luminance, while color receivers process both signals.
Additionally, for compatibility, it is required to use no more bandwidth than the monochrome signal alone; the color signal has to be somehow inserted into the monochrome signal, without disturbing it. This insertion is possible because the spectrum of the monochrome TV signal is not continuous, hence empty space exists which can be utilized. This lack of continuity results from the discrete nature of the signal, which is divided into frames and lines. Analog color systems differ by the way in which empty space is used. In all cases, the color signal is inserted at the end of the spectrum of the monochrome signal. In order to be able to separate the color signal from the monochrome one in the receiver, a fixed frequency sub carrier has to be used, this sub carrier being modulated by the color signal. The color space is three dimensional by the nature of the human vision, so after subtracting the luminance, which is carried by the base signal, the color sub carrier still has to carry a two dimensional signal. Typically the red (R) and the blue (B) information are carried because their signal difference with luminance (R-Y and B-Y) is stronger than that of green (G-Y).
SECAM differs from the other color systems by the way the R-Y and B-Y signals are carried. First, SECAM uses frequency modulation to encode chrominance information on the sub carrier. Second, instead of transmitting the red and blue information together, it only sends one of them at a time, and uses the information about the other color from the preceding line. It uses a delay line, an analog memory device, for storing one line of color information. This justifies the "Sequential, With Memory" name. Because SECAM transmits only one color at a time, it is free of the color artifacts present in NTSC and PAL resulting from the combined transmission of both signals. This means that the vertical color resolution is halved relative to NTSC. It is however not halved compared to PAL. Although PAL does not eliminate half of vertical color information during encoding, it combines color information from adjacent lines at the decoding stage, in order to compensate for "color sub carrier phase errors" occurring during the transmission of the Amplitude-Modulated color sub carrier. This is normally done using a delay line like in SECAM (the result is called PAL DL or PAL Delay-Line, sometimes interpreted as DeLuxe), but can be accomplished "visually" in cheap TV sets (PAL standard). Because the FM modulation of SECAM's color sub carrier is insensitive to phase (or amplitude) errors, phase errors do not cause loss of color saturation in SECAM, although they do in PAL. In NTSC, such errors cause color shifts.
The color difference signals in SECAM are actually calculated in the YDbDr colour pace, which is a scaled version of the YUV color space. This encoding is better suited to the transmission of only one signal at a time. FM modulation of the color information allows SECAM to be completely free of the dot crawl problem commonly encountered with the other analog standards. SECAM transmissions are more robust over longer distances than NTSC or PAL. However, owing to their FM nature, the color signal remains present, although at reduced amplitude, even in monochrome portions of the image, thus being subject to stronger cross color even though color crawl of the PAL type doesn't exist.
Though most of the pattern is removed from PAL and NTSC-encoded signals with a comb filter by modern displays, some can still be left in certain parts of the picture. Such parts are usually sharp edges on the picture, sudden color or brightness changes along the picture or certain repeating patterns, such as a checker board on clothing. Dot crawl patterns can be completely removed by connecting the display to the signal source through a cable or signal format different than composite video (yellow RCA cable) or a coaxial cable, such as, S-video. FM SECAM is a continuous spectrum, so unlike PAL and NTSC a digital Comb Filter can't entirely separate.
The idea of reducing the vertical color resolution comes from Henri de France, who observed that color information is approximately identical for two successive lines. Because the color information was designed to be a cheap, backwards compatible addition to the monochrome signal, the color signal has a lower bandwidth than the luminance signal, and hence lower horizontal resolution. Fortunately, the human visual system is similar in design: it perceives changes in luminance at a higher resolution than changes in chrominance, so this asymmetry has minimal visual impact. It was therefore also logical to reduce the vertical color resolution.
A similar paradox applies to the vertical resolution in television in general: reducing the bandwidth of the video signal will preserve the vertical resolution, even if the image loses sharpness and is smudged in the horizontal direction. Hence, video could be sharper vertically than horizontally. However, because of the interlacing, vertical resolution is effectively not as great as the number of scan lines. Additionally, transmitting an image with too much vertical detail will cause annoying flicker on television screens, as small details will only appear on a single line, and hence be refreshed at half the frequency. Computer-generated text and inserts have to be carefully low-pass filtered to prevent this.
How SECAM video standard works?
Like PAL, SECAM also has 625 scan lines and is based on 50 Hz. SECAM uses two color difference signals and modulates them onto alternate lines, and through a built in delay both are available at the same time. This eliminates phasing, and with FM transmission, and color recovery so good, saturation was unnecessary. While NTSC and PAL transmit the luminance and chrominance signals simultaneously, SECAM transmits luminance continuously and generates only one of the two chrominance signals on any given line. The frame rate is 25 frames per second (It has a field rate of fifty fields per second) to provide compatibility with the European electrical supply frequency, and the number of scanning lines is 625 as in PAL. SECAM has a horizontal rate of 15.625 KHz. SECAM suffers from the visibility of the sub-carrier signals particularly in the mid-gray and white signals. This visibility detracts from its black and white compatibility. SECAM is not compatible with PAL or NTSC.
The PAL/SECAM format (Phase Alternating Line/Sequential Colour with Memory), used in Europe for Hertzian television, makes it possible to code videos on 625 rows (only 576 are displayed because 8% of the rows are used for synchronization), at a rate of 25 images per second with a 4:3 format (i.e. with a 4/3 width/height ratio).
However, at 25 images per second, many people perceive a beat in the image. Thus, since it was not possible to send more information due to band-width limitations, it was decided to interlace the images, i.e. to send the even rows initially, then the odd rows. The term “field” thus indicates the “half-image” formed either by the even rows, or by the odd rows. The whole transmission consisting of two fields is called the interlaced screen. When there is no interlacing the term progressive screen is used.
SYSTEM SECAM B,G,H SECAM D,K,K1,L
Line/Field 625/50 625/50
Horizontal Frequency 15.625 kHz 15.625 kHz
Vertical Frequency 50 Hz 50 Hz
Video Bandwidth 5.0 MHz 6.0 MHz
Sound Carrier 5.5 MHz 6.5 MHz
"What will happen if we purchase a TV set in Japan and switch it on in Malaysia?"
If you purchase a TV set in Japan and switch it on in Malaysia, you need digital television transition, Digital-to-analog converters, Digital Converter Set Top Boxes, and Television license.
Digital television transition
The digital television transition is the process in which analog television broadcasting is converted to and replaced by digital television. This primarily involves both TV stations and over-the-air viewers; however it also involves content providers like TV networks, and cable television conversion to digital cable.
In many countries, a simulcast service is operated where a broadcast is made available to viewers in both analog and digital at the same time. As digital becomes more popular, it is likely that the existing analogue services will be removed. In some cases this has already happened, where a broadcaster has offered incentives to viewers to encourage them to switch to digital. In other cases government policies have been introduced to encourage or force the switchover process, especially with regard to terrestrial broadcasts. Government intervention usually involves providing some funding for broadcasters and, in some cases monetary relief to viewers, to enable a switchover to happen by a given deadline.
The switchover for individual countries varies; it could either happen in small steps, such as with the United Kingdom where each region has a separate date to switch off, or the whole country could switch in one go, as did Finland on 1 September 2007. The most recent country to switch off all analogue services was Malta on 31 October 2011; the next country to switch off all analogue services will be France on 30 November 2011.
Purpose of the transition
Almost all analog formats in current use were standardised between the 1940s and 1950s and have had to be adapted to the technological innovations since then. Initially offering only black and white images with monophonic sound, the formats have had to be modified to broadcast in colour, stereo sound, SAP, captioning, and other information all while being backwards compatible with televisions unable to use the features. Additionally, engineers have had to implement these protocols within the limits of a set bandwidth and the tolerances of an inefficient analog format.
However during this time, the application and distribution of digital communications evolved. Digital television transmission is more efficient, easily integrating other digital processes. Analogue features have difficulty or cannot do the extra digital features.
- For the end-user, digital television has potential for resolutions and sound fidelity comparable with blu-ray home video and with digital multiplexing, it is also possible to offer subchannels, distinct simulcast programming, from the same broadcaster.
- For government and industry, digital television reallocates the radio spectrum so that it can be auctioned off by the government. In the subsequent auctions, telecommunications industries can introduce new services and products in mobile telephony, wi-fi internet, and other nationwide telecommunications projects.
Digital-to-analog converters
After the switch from analog to digital broadcasts is complete, analog TVs will be incapable of receiving over-the-air broadcasts without the addition of a set-top converter box. Consequently, a digital converter box – an electronic device that connects to an analog television – must be used in order to allow the television to receive digital broadcasts.[57] In the United States, the government is subsidizing the purchase of such boxes via their coupon-eligible converter box program, funded by a small part of the billions of dollars brought in by the spectrum auction of 12 of the upper UHF channels. The program is managed by the Department of Commerce through its National Telecommunications and Information Administration.[
Digital Converter Set Top Boxes
If you buy a Digital-to-Analog converter then your current TV will work just fine. An external converter box can be added to non-digital televisions to lengthen their useful lifespan. A set-top box (STB) or set-top unit (STU) is a device that connects to your television and an external source of signal, turning the signal into content which is then displayed on the television screen. Special digital set top boxes are available for receiving digital television broadcasts on TV sets that do not have a built in digital tuner (HDTV Ready).
Television licence
A television licence (or broadcast receiving licence) is an official licence required in many countries for the reception of television (and sometimes also radio) broadcasts. It is a form of hypothecation tax to fund public broadcasting, thus allowing public broadcasters to transmit television programmes without, or with only supplemental, funding from radio and television commercials.
History
The early days of broadcasting presented broadcasters with the problem of how to raise funding for their services. Some countries adopted the advertising model, but many others adopted a compulsory public subscription model, with the subscription coming in the form of a broadcast licence paid by households owning a radio set (and later, a TV set).
The UK was the first country to adopt the compulsory public subscription model with the licence fee money going to the BBC, which was formed on 1 January 1927 by Royal Charter to produce publicly funded programming yet remain independent from government, both managerially and financially. The licence was originally known as a radio licence.
With the arrival of television some countries created a separate additional television licence, while others simply increased the radio licence fee to cover the additional cost of TV broadcasting, changing the licence's name from "radio licence" to "TV licence" or "receiver licence". Today most countries fund public radio broadcasting from the same licence fee that is used for television, although a few still have separate radio licences, or apply a lower or no fee at all for consumers who only have a radio. Some countries also have different fees for users with colour or monochrome TV. Many give discounts, or charge no fee, for elderly and/or disabled consumers.
Faced with the problem of licence fee evasion, some countries choose to fund public broadcasters directly from taxation or via other less avoidable methods such as a co-payment with electricity billing. National public broadcasters in some countries also carry supplemental advertising.
The Council of Europe created the European Convention on Transfrontier Television in 1989 that regulates among other things advertising standards, time and the format of breaks, which also has an indirect effect on the usage of licensing. In 1993, this treaty entered into force when it achieved 7 ratifications including 5 member states. It has since been acceded to by 34 countries, as of 2010
Television licences around the world
The Museum of Broadcast Communications in Chicago[2] notes that two-thirds of the countries in Europe and half of the countries in Asia and Africa use television licences to fund public television. TV licensing is rare in the Americas, largely being confined to French overseas departments and British territories
The actual cost and implementation of the television licence varies greatly from country to country. The rest of this section looks at the licence fee in a number of countries around the world
Japan
In Japan, the annual licence fee for terrestrial television broadcasts is ¥15,490 (€144.29) (slightly less if paid by direct debit) and ¥25,520 (€237.72) if you receive satellite broadcasts.[55] There is a separate licence for monochrome TV, and fees are different in Okinawa. The Japanese licence fee pays for the national broadcaster Nippon Hōsō Kyōkai (NHK).
While every household in Japan with a television set is required to have a licence, it was reported in 2006 that "non-payment [had] become an epidemic" because of a series of scandals involving NHK.[56] As reported in 2005, "there is no fine or any other form of sanction for non-payment".
References:
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