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Advanced Television Systems Committee (ATSC)
The Federal Communications Commission (FCC) has adopted rules that will help smooth the transition to digital television (DTV) for millions of Americans. The FCC’s rules mandate that a digital terrestrial module be included in all TVs.
Congress has determined that U.S. broadcast (or terrestrial) television services must eventually convert completely to digital operation. Cable TV and other video media are also transitioning to digital. As DTV is delivered digitally, it allows for the delivery of signals virtually free of interference. DTV broadcasters will be able to offer television with movie-quality pictures and Dolby digital surround sound, along with other enhancements. DTV technology is more efficient than analog technology and will allow the same number of stations to broadcast using less spectrum.
The FCC’s actions are important to the digital transition because they will facilitate the direct connection to a free digital terrestrial service from the same broadcasters that provide analog service. Consumers will be able to plug a TV set into an antenna virtually anywhere in the U.S., and if the module meets the Advanced Television Systems Committee’s (ATSC) A/74 specification, the TV will receive clear digital service. Unfortunately, the FCC’s ruling on modules does not mandate that the receiver meet the ATSC specification, which means consumers must be sure to check the performance of the TV they buy. Proto provides ICs that allow modules to cost effectively meet the demanding ATSC specification.
The FCC has recently expanded its rules to cover cable modules, yet this is not a mandate. If a TV is labeled as “Digital Cable Ready” it must also include a Quadrature Amplitude Modulation (QAM) module. This type of television is called “Plug-and-Play” TV .
The first generation of Plug-and-Play sets will be able to receive one-way programming only, including analog basic, digital basic, and digital premium cable programming. If consumers want to receive advanced digital cable services such as video-on-demand, the cable operator’s enhanced program guide, or interactive data-enhanced television service, they will need an STB (set-top box). STBs may also be required to receive other cable operator-provided services, such as a personal video recorder. Negotiations are underway between the cable and consumer electronics industries to establish standards that will permit Plug-and-Play sets to provide advanced two-way services. Stay Tuned!
In addition to the ATSC specifications for terrestrial module requirements, the FCC has designated the Society of Cable and Telecommunication Engineers (SCTE) as the standards body for Plug-and-Play TV cable specifications. SCTE DVS538 will soon be publicly released as the cable standard for U.S. digital cable TV. Proto participates in both ATSC and SCTE standards bodies.
All DTVs shipped into the U.S. must include a digital terrestrial ATSC module as defined by FCC rule part 15.117. Following is the FCC’s phase-in schedule for both terrestrial and Plug-and-Play TV (if labeled “digital cable ready”):
Plug-and-Play designs are categorized into two different architectures, either dual conversion, where the design uses an up-converter to an IF and then a downconverter to the IF output, or a single conversion using an MOPLL (Mixer-Oscillator with Phase Locked Loop) device. Although the MOPLL design is lower cost, no one has met the ASTC specification based on the complexity of dealing with image signals within single conversion architectures. For this reason, Proto has introduced a unique single conversion module that includes a special signal mixer design that removes most of the image during the mixing process. This is called an image reject mixing. Image reject single-conversion ICs offer the lowest cost ATSC receiver solutions possible – and Proto is the leader in these IC solutions.
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