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Alaska Business License # 712765
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World Television Broadcast Standards and Voltage Guide Television and video equipment lack worldwide compatibility. This means the video cassette or DVD you watch on a television using a playback device in one country may not playback as expected using equipment connected to a television in another country. Broadcast signal and transmission technologies and specifications differ, just as language and dialect differ around the world. Most countries around the world use one of three main analog television broadcast standards. These three main standards are NTSC, PAL and SECAM. Although PAL and NTSC are very similar, each standard, especially SECAM, is incompatible with the other. For example, a video recording made in the UK using PAL standards could not be played on US standard VCR's or shown on the TV. Unlike PAL and NTSC, analog SECAM television cannot easily be edited in its native analog form.
SECAM stands for Sequential Electronique Couleur Avec Memoire (French for "sequential color with memory"). The French began development in 1956 and introduced for consumer use in 1967. A French and Eastern European color TV standard that broadcasts an analog signal at 819 lines of resolution 25 interlaced frames per second (50 half frames per second). Mostly used in France, it is slowly being switched over the the European PAL standard. Digital Television has over a dozen broadcast and non-broadcast standards with different resolutions, aspect ratios, and scan type. Some are High Definition Television (HDTV) and others are not. The two primary HDTV standards are720p and 1080i where "p" indicates progressive scan and "i" indicates interlaced scan. Like NTSC and PAL, interlaced digital broadcasts use interlacing at 50 or 60 times a second (50 or 60 half frames per second). 1080i50 is used in areas traditionally using PAL and 1080i60 is used in areas traditionally using NTSC. Progressive scan refresh the entire frame each time and the rates are 24, 25 and 30 frames per second. This is emerging technology and not widely available to consumers or having a government imposed standard in any region or country.
Many alleged causes for the international broadcast standard differences are offered such as national pride, political results of the cold war, differences on quality of image, and a requirement for compatibility with older monochrome (Black & White) TV receivers. Regardless each analog broadcast standard has image resolution input and output difficulties and the different digital broadcasting standards also have pertinent image resolution input and output difficulties. Consequently the political and technology debate pertaining which digital television (DTV) broadcast standard will probably result in the better image will continue to cause countries to adopt differing digital broadcast standards around the world for many more years. Converting from one analog broadcast standard to another means changing the video frame rate from 30 frames per second in NTSC to 25 frames per second in PAL and the scan line rate of 525 lines in NTSC to 625 lines in PAL. Converting PAL or NTSC to SECAM is of dwindling need as televisions sold in SECAM countries support SECAM and PAL and manufacturers are no longer producing video recording and playback equipment that accept or output a SECAM analog signal. Converting from an analog broadcast standard to a digital broadcast standard includes accommodating a digital TV screen width to height ratio of 16:9 which differs from the analog TV 4:3 ratio in addition to possible need to change the frame rate.
Just like analog broadcasts, different regions of the world have different digital broadcasting formats. There is no industry standard for digital broadcasting format either. But from the consumer's perspective, it does not matter as most DTV sets available to consumers can receive and display most if not all digital formats. Initially and for the near future, all DTV's will be capable of displaying analog television signals as investors and policy makers worldwide have been forced to confront the prospect of digital HDTV becoming available while analog-based systems remain in use. You should be able to receive Broadcast DTV with any standard outdoor antenna; however, it is probable you might need to use a highly directional antenna pointed just right as reception of broadcast digital HDTV either works beautifully or fails catastrophically. Receiving the same digital signal from several directions at slightly different times (having bounced back and forth off of buildings or terrain) results in Multipath interference. Multipath reception and is the cause of ghosts on analog NTSC/PAL/SECAM TVs and of unwanted interference sounds on your FM car radio. Consequently, the exact style of antenna that you will need for optimal reception may vary depending on your geographic location and distance to the transmission source. Digital transmission promises to resolve the signal-compression problem and thereby reach more households using terrestrial delivery rather than being limited to only cable and satellite broadcast. It also permits TVs to become computerized information and entertainment centers. DTV bring with a new viewing standard called High Definition (HD). HDTV is a rectangular "Wide Screen" having a width to height ratio of 16:9. An analog TV has a 4:3 ratio. High-Definition Television, a new type of digital television that provides much better image quality than current televisions based on the analog NTSC, PAL, and SECAM standards. There are a number of competing HDTV standards, which is one reason that the new technology has not been widely implemented. All of the standards support a wider screen than NTSC/PAL/SECAM and roughly twice the resolution. To pump this additional data through the narrow TV bandwidth, images are digitized and then compressed before they are transmitted and then decompressed when they reach the TV. Broadcasting bandwidth for terrestrial television delivery is 6 megahertz per station for television). HDTV is a type of television signal, which is scheduled by government mandate to replace the current US standard, NTSC, by the year 2006. HDTV is different from NTSC in several ways. First, HDTV is broadcast in the 16:9 aspect ratio as compared NTSC's 4:3 aspect ratio. Second, HDTV resolutions are increased from (if expressed in computer resolution terms) 640 x 480 to either 1922 x 1080 (or 1080i) or 1280 x 720 (or 720p). Thirdly, because the signal itself is digital rather than analog, it can carry a lot of information, including full digital audio with multiple channels. All digital television signals - whether for cable, satellite, or terrestrial reception - are compressed before transmission using the MPEG-2 compression standard, and must be decompressed using an MPEG-2 decoder after reception. Compression enables broadcasters to transmit several digital channels in the same bandwidth as is required to transmit a single analog channel. Direct Digital Broadcast Satellite and Digital cable differ from local area terrestrial digital television in the encoded data stream is also encrypted by the cable or direct broadcast satellite service provider. These companies provide a signal feed for a monthly fee and require the use of their proprietary decoder boxes. Digital TV provides high quality programming and more content via free over-the-air broadcasts.
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