DTV and HDTV - Why You Need To Understand the Difference
There are so many acronyms used in defining television
technology that is difficult to keep it all straight, and even
worse, sometimes the acronyms are almost the same. That's the
case with DTV and HDTV. At first glance they would seem to be
very similar, and yes they are definitely related, but there are
also significant differences as well.
DTV stands for Digital TV, and HDTV stands for High Definition
TV. To understand DTV, you have to go back before cable and
satellite TV to the time when all broadcasts were picked up by
antenna. Those television signals were broadcast in analog
format, which is severely limited in how much audio and video
information it can transmit. Back then all TV sets received
analog signals and the main choice you had to make was how large
the TV screen was going to be.
When first cable and then satellite came on the scene, they
changed things dramatically. Instead of just sending analog
signals they were able to broadcast in digital instead. That
immediately improved both the picture and sound for televisions
that were ready to receive digital signals. The improved video
was far sharper and smoother than anything before, and the sound
quality took a similar leap forward too. So DTV is simply a
higher standard for TV broadcasting than was available in
previous analog TV systems.
HDTV however, is the next evolutionary step in digital
broadcasting. It takes DTV to a new level and makes both the
television sound and video so much better. For instance, many
DTV programs are sent in 525i format, which means that 525 lines
of information are displayed on the screen and interlaced, or
shown in alternate order. In other words, all the odd lines are
shown in 1/10 of a second and then all the even lines are shown
in the next 1/20 of a second. Because it all happens so fast you
never clearly see the alternating pattern, but it is there.
Broadcasts made in HDTV however can reach up to 1080p, which is
a standard where 1080 lines of information are shown on the
screen and they are all shown together in a progressive scan
instead of interlaced. What that means for you is a picture with
much higher clarity and definition and action sequences that are
much smoother to watch.
There are also other features of the HDTV format, including
widescreen and Dolby 5.1 surround sound that take television
viewing to a whole new level too, so DTV was the start of all of
this improved entertainment, but HDTV is where we will really
see the benefits unfold for all of us.