Television is now in the process of converting from analog to digital technology. The significance of this change is greater than the introduction of color TV in the 1960’s, but more complicated since conversion will require new equipment for all consumers. Unlike color TV, digital television (DTV) uses a new kind of signal that does not fit within the structure of the old signal. "DTV" refers to a specific standard being implemented in the United States to carry a television signal in digital form through all stages of its transmission, not just for digital equipment such as video tape recorders and satellite receivers that have already been used in conjunction with analog television.

The Federal Communications Commission (FCC) is the regulatory authority for the use of DTV. The Commission required TV stations in the top ten markets to begin broadcasting digital signals on separate channels along with their current analog signals. Stations in smaller markets are being phased in, and all commercial stations are expected to broadcast a digital signal by 2002. By 2003, all public stations are expected to go digital. The FCC will allow broadcasters to pull the plug on analog by 2006, although many people in the electronics and communications industries feel that analog TV may persist for a few years longer (Churchill).

Digital television is being promoted for three distinct advantages: better picture, better sound, and more functions and flexibility. A digital picture has better color and is free from ghost images and snow. In addition, the DTV format allows for greater resolution than analog TV, a resolution high enough to be known as high definition television (HDTV). The level of resolution used by analog TV is called standard definition television (SDTV).

The DTV format actually allows a flexible range of 18 sets of picture specifications to be used. HDTV has a specification called 1080i, which is so named because it has 1,080 horizontal lines of resolution transmitted in an interlaced manner, which means that when the lines of each frame of the video are sent, only the even-numbered lines are sent for one frame, then only the odd-numbered lines of the next frame. Another HDTV format is 720p, which has 720 horizontal lines, but all lines are progressively sent for each frame. One SDTV format is 480p (480 progressive horizontal lines).

A DTV signal can carry five channels of digital audio at the level of quality used by compact discs. This accommodates the demand for high-quality, movie theater-style sound. In the realm of analog television, this level of sound quality can only come from recordings, digital satellite transmissions, or digital cable signals, not over the air from a local TV station (Churchill).

An example of DTV’s extra function and flexibility is the system called Program and System Information Protocol (PSIP), a data service that allows TV users to view schedules and read descriptions of programs transmitted through cable or on the air. This is one standard that the National Cable Television Association and the Consumer Electronics Association agreed on; it is probable that cable operators and television stations may devise numerous ancillary data services related to entertainment or business. The nature of computerized information increases the number and different types of information services that can share a TV channel. Additionally, broadcasters and studios can watermark DTV signals to preserve copyright information (Mannion, "Last").

An important feature of DTV is its ability to multicast SDTV signals on one digital channel, which occupies the same bandwidth as an analog channel. HDTV signals, which create more data, cannot effectively be compressed to allow more than one on a channel, but broadcasters have the flexibility to choose between offering multiple programming options and offering a high definition picture. Sufficient compression will allow local broadcasters to compete with the offerings of cable and satellite services (Bain, Yang).

DTV signals are modulated on a radio frequency signal in a form called 8-level vestigial sideband modulation (8-VSB). 8-VSB has continually been upheld by the FCC over a rival form of modulation called coded orthogonal frequency division multiplexing (COFDM) (Mannion, "FCC"). Some of the initial testing found that COFDM provided better reception, especially in environments where reflected radio signals from large objects hinder reception. COFDM is susceptible to impulse noise (such as that generated by household appliances), and it requires greater transmitter power to achieve the same range as 8-VSB. One early test found that 8-VSB performed so poorly that it was not receivable in locations that analog signals were receivable (Powell). Manufacturers claim that later testing with improved 8-VSB receivers showed better performance, and they expect to produce even better receivers in the near future. The difference between 8-VSB and COFDM is so small and debatable, though, that COFDM has been adopted into Europe’s Digital Video Broadcasting (DVB) standard, and COFDM is being found worthy of reexamination (Churchill). The United States is not the leader in digital standards.

In the United States, DTV is replacing an analog system with a format known as NTSC, which stands for "National Television Systems Committee." This format has been in use since 1954. It uses 525 horizontal lines of picture resolution (Churchill). This type of TV signal did have the flexibility to add a few features such as stereo sound, the second audio program feature, closed captioning, and the transmission of other data. However, analog signals can be distorted by interference, which means that the color can be changed, snow can appear, and objects such as buildings or mountains can create ghost images by reflecting delayed signals, all quite easily, even with expensive equipment and powerful transmitters. Digital signals will protect the integrity of their information so long as their data can be discerned from noise and multiple reflected signals that receivers will always get from signals broadcast through the air. So it is evident that digital television is significantly better technology.

It was not easy for electronics manufacturers and the FCC to develop and agree on the DTV standard. Any industry involved with communications has a difficult time setting standards on formats that are used. A company may support its own standard because it can license it and profit from it for years to come if it becomes commonly used, or a company may support a standard simply because it believes it is superior. In order to make progress in advancing technology, manufacturers, research groups, and government agencies join together to form organizations that discuss and propose standards. Ultimately, a government agency decides on what kinds of signals are allowed on airwaves or cable systems.

In the 1980’s, the idea of HDTV created a stir, causing electronics manufacturers to engage in research and develop prototype models of HDTV equipment. This research began in analog, however, and the FCC fortunately did not begin its campaign to replace NTSC television until 1987 when it set into motion research on all-digital television. This was after the U.S. and Europe rejected an analog HDTV format proposed by Japan, who proceeded to adopt it for broadcast (Lemm). Considering that the NTSC format has now persisted for over 40 years, it is possible that we in the U.S. may have been committed to analog TV for another 40 years if we had adopted Japan’s format.

In the case of digital television in the United States, the Federal Communications Commission chose a standard called A/53 from the Advanced Television System Committee (ATSC). This is what "DTV" refers to. In turn, A/53 is a set of standards that include AC-3 for sound from Dolby Laboratories, and MPEG-2 for video from the Moving Picture Experts Group (Digital).

The transition to digital television involves considerable expense. Consumers will have to buy all new equipment to use all the functions of DTV, and they will have to choose the equipment carefully or risk needing more expensive equipment. (For example, if they buy DTV sets that are not cable-ready, they would then require expensive cable boxes.) The first converters that simply receive DTV and convert it to an analog signal for an existing analog television have been priced around $1,000. DTV sets with a high definition picture tube may currently cost $3,000. There is no consumer-grade recording equipment for DTV available yet, but because of the new technology, it will be considerably more expensive than current analog VCRs; additionally, there are competing recording formats in the works, so the expense will be greater for the consumers that choose a format that loses popularity later and must be replaced.

Broadcasters are also incurring considerable expense to convert to digital. They are being required to simulcast in digital and analog, so they are building new digital transmitting facilities, often with a second tower, and having to maintain both stations. The digital station requires the purchase of all-new production equipment to create, edit, and process programming, including HDTV cameras that may cost $30,000 each (Churchill).

Expense is not the only problem faced by consumers and broadcasters: Cable television systems currently present an obstacle to the benefits of digital television. While they already have some digital signals of their own, there may be trouble in delivering local over-the-air stations signals to cable subscribers. Cable uses a digital signal that is different from over-the-air DTV, and its driving force is quantity, not quality. The problem is that cable companies may not want to pass the complete signal from local broadcasters on to their subscribers, or possibly not at all as long as the local stations simulcast an analog signal (Yang).

Cable is using the same MPEG-2 format for the picture data, but it is transmitted in a signal that uses quadrature amplitude modulation (QAM). Fortunately, manufacturers have decided to allow their newest DTV equipment to receive both QAM and 8-VSB, so these two different radio-frequency signals are expected to coexist in the new digital era without requiring cable boxes for use with digital cable (Mannion). However, current digital cable boxes will still become obsolete, and here is why:

Digital cable was originally intended as a means of compressing multiple standard definition television channels into the space of one analog channel, just acting as a digital step for a traditional analog TV system. Since any cable system has a limited number of analog channels, this provides more channels that can actually be delivered to subscribers. The original digital cable boxes that are in common use send a signal to an analog TV. However, these boxes are not capable of receiving the higher resolution that DTV will carry, and they certainly will be of no benefit to a digital TV set since they put out an analog signal. Finally, they will not receive the 8-VSB signal if and when cable systems carry them.

Cable operators generally are not interested in carrying the full signal that local broadcasters will be using. If a TV station broadcasts an HDTV signal, that program will require the full space of a regular channel. If a cable operator reduces its resolution, then that same channel can be compressed among other channels in the same space of a regular channel. If cable must carry the full HDTV signal, then it will have less space to carry extra channels (Churchill).

The FCC is expected to step in at this crucial step of the analog-to-digital conversion process. The Commission is currently waiting to see if the marketplace will resolve this problem on its own (in line with Commission philosophy), but it will at the very least need to provide guidelines on how cable systems will switch between local broadcasters’ analog and digital signals. It may encourage the sales of DTV equipment if cable systems add digital signals early and maintain duplicate analog signals during the transition period, but subscribers would lose significant programming choices with such duplication (Burger).

Fortunately, the FCC has already solved one important cable issue: how to receive conditional-access channels. With analog television, cable companies have generally required their subscribers to lease a cable box that receives and descrambles signals for subscription and pay-per-view channels. This redundancy of receivers with digital equipment would be considerably expensive, so the FCC has made rules in favor of the consumer. By July 2000 cable must allow consumer-purchased equipment to receive and decrypt digital cable channels (Digital). In order make use of a single digital receiver, point-of-deployment (POD) modules will be used, and cable companies may actually retain ownership of these. These modules will take the form of a card that will insert into a receiver or television set, and they will be activated by a data signal from the cable operator. The POD has been devised by the OpenCable specification, a product of several communications companies that comprise an organization called Cable Television Laboratories (Mannion).

A further problem in DTV is the interconnectivity of digital home entertainment equipment, but this is mostly just a temporary problem of new technology because a standard connector was not agreed upon until after DTV’s launch. When playback and recording devices for DTV are available, the most efficient way to connect them will be to have them share raw data. This is different from analog equipment because, traditionally, the VCR (or DVD player) has used a coaxial cable to send a radio-frequency signal that is modulated to imitate a regular signal sent from a TV or cable station. Each analog VCR or cable box has a receiver to pick up the RF signal and a modulator to send a new RF signal to the next device in the line (see Figure 1). Many digital television sets that have been sold have not carried any sort of data connection, and to connect new DTV accessories their owners will need to purchase converters. Furthermore, the first HDTV cable boxes carried a certain kind of serial data connection that has lost favor in the consumer electronics industry (Krauss). The Institute of Electrical and Electronics Engineers has devised a type of data bus known as the IEEE 1394 that uses parallel conductors. This type of bus is also called "FireWire" to describe its high data rate, and it is now considered the standard type of connector to allow DTV devices to be connected together (see Figure 2)(Mannion). Generally, there should only be one receiver to accept an RF signal that will be converted into the data shared by all other devices. Receivers are being sold separately from the screens (Yang). Consumers should be careful to avoid purchasing equipment that does not have FireWire connectors.

To make the transition to DTV complete, consumers will have to own the equipment that can receive it. The complete digital television sets are nearly prohibitively expensive, but several companies are now offering an innovative product that will speed the introduction of DTV into viewers’ homes: PC cards.

These computer expansion cards are economical for owners of personal computers because they make use of the digital monitor, immense processing power, and stereo sound that any relatively new computer is likely to already have. Computer monitors generally provide resolution near the high definition range, above that of the best analog TV sets. PC cards are available for prices in the range of only a few hundred dollars (Mannion).

Aside from personal computers, compromises in quality can be made to enter the DTV arena. Digital televisions that use smaller picture tubes without the full HDTV resolution are naturally cheaper, and this is not an unusual type of compromise. Smaller analog television sets often carry less than even standard resolution, perhaps only 300 lines. It is important to consider that the full resolution of a small HDTV screen cannot even be easily discerned from across a room.

TV viewers that do not have a computer and are reluctant to pay for an HDTV-capable TV set can still use a converter to receive DTV signals and display them on their existing analog set. This will still deliver the benefit of color stability, picture clarity, programming information, and possibly Dolby Surround Sound for those with stereo equipment. All digital equipment, from PC cards to large HDTV sets, will experience falling prices, just as pocket calculators, VCRs, and cellular phones have done in the past, so waiting a few years will help those consumers with smaller budgets.

Manufacturers have a role in promoting their HDTV sets and promoting the digital transition. Even though DTV stations with HDTV programming are not widely available, their sales forces are stressing the improved quality that HDTV screens can provide for analog signals. With line doubling and other techniques, analog pictures can appear smoother and easier on the eyes. Manufacturers are also aware that their customers need to be well-educated before purchasing so that they will understand the capabilities that they may or may not have with new products (Churchill).

Many of the remaining questions concerning what kind of digital signals cable will carry, what recording formats should be used, and what technical details equipment should have will be answered by a "snowball effect" (Bain). Competing formats or features are being offered initially, but when DTV gains popularity, consumers will have a clearer picture of the popularity of particular options that are available. Then, when one option gains market share over a competing option, it will be perceptible and affect the consumers’ decisions following that gain, whether or not it is technically the best choice. For example, the VHS and Beta videotape formats competed in the 1980s. Although Beta is technically superior, consumers steered away from it when it became known that there was a greater number of programs available on VHS tapes.

At first glance, converting to digital television seems to be a undue burden on industries and consumers. Considering the quality of analog TV and all the services that deliver it versus the expense of digital equipment, the FCC is perhaps misled to believe in the notion that any technology described by the word "digital" is better than "analog" and should not use the power of law to force a conversion to it. With closer inspection of DTV, however, the burden becomes an investment, and the digital technology being put to use surpasses the analog technology in several ways.

Consumers have the options of converters and PC cards if they wish to receive DTV now, and if they wait a few years, prices of DTV sets will be lower, and in the meantime they may enjoy their analog sets that will become old and inevitably require replacement. Consumers will benefit from having film-quality television available with better color and sound. With today’s high level of technology available in television equipment and production techniques, the transition to digital television is being made at the appropriate time.

Consumers should learn about the digital television equipment they will be operating soon, if they have not started already. Manufacturers should be responsible in providing compatibility and flexibility in their DTV prodcucts. Finally, electronics technicians should begin learning about the equipment that will become universal and standard in every household.