Digital Vs. Analog TV Tuners
A TV tuner is the component of a television set, video component or computer that allows it to receive and decode TV signals. Older TVs came equipped with analog tuners, while models produced since the mid 1990s have upgraded to digital tuners. Computer tuner cards can be either internal or external devices, and can also act as a video capture card to store and play video on a hard drive.
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Analog Tuners
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The standard for black and white analog TV tuners was created in 1940 when the FCC formed the NTSC (National Television Systems Committee), with the standard for color analog tuners following in 1953. The NTSC standards include the 4:3 aspect ratio that comprises the screen size, 525 horizontal scan lines of resolution and 30 frames per second.
Digital Tuners
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In 1982, the FCC formed the ATSC (Advanced Television Systems Committee) to set the standards for digital TV tuners, which were developed and adopted by 1996. These standards enabled televisions to receive digital signals, have a wider aspect ratio of 16:9 (similar to movie theater screens) and have a resolution of up to 1,080 vertical and 1,920 horizontal pixels for high-definition video. It also includes Dolby Digital AC-3 for surround sound audio.
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Digital Technology
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With digital tuners, the signal is received as a stream of data in the MPEG-2 (Motion Pictures Experts Group) format, decoded and decompressed to be viewed by the television. The picture resolution, up to six times greater than that of analog tuners, provides the high-definition video as well as the 5.1 channel audio. The expanded data capacity also allows for the reception of subchannels along with the main channels that are broadcast, which was not possible with analog TV.
Progression
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As digital tuners became available, some TVs were manufactured with both NTSC and ATSC tuners to take advantage of both types of broadcasts, and add-on ATSC tuner cards were developed to connect to computers that only had the analog tuner cards to allow them to receive digital and HD video. The analog NTSC tuners, for both televisions and computers, began to be phased out as digital technology became more popular.
Digital Transition
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The United States completed its transition to all-digital broadcasting in June 2009. To prepare for this, the FCC had mandated that by March 2007 every tuner installed in a TV or related component must be a digital tuner. Now, older TVs with an analog tuner cannot receive over-the-air broadcasts without the aid of a cable or satellite receiver box or a digital-to-analog converter box. The converter boxes were also necessary for other components such as VCRs not connected to cable or satellite receivers equipped with a digital tuner to process the signal for the television.
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