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.
About The Author
Jim Johnson writes about consumer related matters. Find out more about directtv hdtv and hdtv reviews at our HDTV website.
