:: The nitty-gritty about "Digital TV" ::

There is much confusion about the term "Digital TV". There is a significant gap between what the general public understands about this term and the truth. This is in no small measure due to the failure of the press to understand the concept before they write about it. We will even go so far as to say that some less than scrupulous companies have allowed misconceptions to boost their sales of products and services. Some have even promoted the confusion to benefit their bottom line. So here are the facts:

1. Digital TV simply refers to the method of transmission of a TV signal. Instead of using an antenna vibrating at extremely high frequencies to create waves of sound in the air, the transmitting device uses a series of 1 (on) and 0 (off) pulses to represent the signal. Perhaps a better example is the difference between an old vinyl recording and a CD. Under a microscope the grooves in a vinyl record have varying numbers of undulations for a given distance on the surface, let's say an inch of travel, the more undulations per inch, the higher the pitch of the sound. Conversely, fewer undulations per inch produce lower pitched sounds. These undulations are then reconstructed by the electronics into music. On a CD, though, instead of "grooves" of undulations, there are a series of "pits" dug out of the surface. The laser is precisely focused at the standardized pit depth so that if there is no pit present the processor records a A0" because the laser doesn't "see" a reflection that is properly focused. On the other hand, if there is a pit present (a properly focused reflection back to the laser pickup) the laser "sees" a pit as a "1". Hence, billions of tiny pits make up the "1's" that, combined with the non-pitted areas ("0's") make up binary "words" such as "0110001010101111" (16 bit). Combining these "words" at a given frequency (i.e. number of times per second), say 44,100 times per second, comes out of the electronics as music. So, the term "digital" in and of itself tells us nothing about quality at all and it certainly doesn't mean High Definition!
2. High Definition TV is always digital, however, Digital TV is not always High Definition.
3. Cable TV
   • Cable TV signal transmissions can be analog or digital.
   • Analog Cable TV can not be High Definition.
   • "Digital Cable" is not High Definition Cable TV.
   • High Definition Digital Cable is High Definition Digital TV but only a handful of channels are currently available such as: ESPN-HD, HBO-HD, SHOWTIME-HD, NBC-HD, CBS-HD, PBS, Comcast SportsNet.
   • A digital cable box gives you an analog signal (the same as cable with no converter) but adds digital processing of the analog signal to provide enhanced services and more tunable channels so you can view it on your standard TV or your High Definition capable TV but will not give you improved resolution. "Digital Cable" is NOT digital TV.
   • Cable companies get their signal from satellites. They then decode it and send it to their subscribers. The majority of signal interruptions and outages from Cable companies are caused by problems with satellite signal reception.
4. Satellite TV
   • All Satellite TV is digital but NOT High Definition unless ....
   • Satellite TV images, even in standard definition format are generally superior in sharpness and quality to any form of Cable TV except High Definition Cable (not yet available in Harrisburg).
   • High Definition satellite TV is available on a limited number of channels at this time but does not offer the quality of resolution that receiving HDTV off the air (i.e. by using a rooftop antenna) does. DirecTV requires a special oval dish with two "LNB's" and a High Definition receiver while Dish Network requires a completely separate second dish along with a High Definition receiver.
5. Unless you have a TV capable of processing High Definition signals (either analog or digital transmission cables can be used depending on your set), you can not watch High Definition TV from any source.
6. A High Definition capable TV can display either standard definition analog signals, Standard Definition digital signals (SDTV) or High Definition digital signals (HDTV). In other words an HDTV is backwards compatible.
7. An integrated High definition TV has a built in High Definition tuner and can decode a digital signal from a properly aligned antenna into a beautiful image up to roughly 5 times the image quality of a regular analog TV.
8. As of this writing, an integrated High definition TV cannot decode a "High Definition Digital Cable" signal. The use of a "High Definition Digital Cable Box" is necessary since there has only very recently been an agreement between the manufacturers of HDTV's and the Cable companies on a standard decoding scheme. Televisions using this agreed upon decoding scheme (called QAM) may become available later in 2004.
9. Not all High Definition capable displays are in fact capable of the highest degree of HDTV resolution. How's that for a wrench in the works? For example, the highest resolution of HDTV, according to the ATSC ruling that defined the standard for HDTV in December of 1996, is 1080i (pronounced "ten-eighty-I") which means simply 1,080 lines of video information displayed from top to bottom on your screen twice per second. By contrast, the old TV standard we've all grown up with allows only 480 lines maximum in the same space so you can see there is far more information per inch of height on your screen with the new standard. Now 480i is the theoretical limit of the old standard and is rarely experienced in reality. The operational resolution of most standard TV signals is closer to 240 lines (or about half the theoretical limit). So ... the FCC decided to allow Digital TV to come in 18 different flavors ranging from the lowly 480i (digital) SDTV(standard definition TV) all the way up to 1080i HDTV. Therefore, if a TV says that it is HDTV capable that doesn't mean that it is capable of displaying 1080i, only that it can display a signal better than SDTV, 960i for instance. There is a lot more to this as you might imagine but if you're with us this far, you're probably an engineer!
10. A High Definition capable TV can properly display the signal from a progressive scan DVD player only if both components are properly set up. The result is NOT High Definition but is potentially twice as sharp an image as that achievable with a standard DVD player.
11. A regular TV can NOT properly display the signal from a progressive scan DVD player, however all progressive scan DVD players can be set to interlaced mode for use with regular TV's.