Why
it's the Best
To view a high definition picture on a C-Band system you will need a
4DTV receiver, a high definition television and a high definition Decoder
(HDD-200). The HDD-200 is the C-Band solution to getting high definition.
The DigiCipher II HDD-200 is a state-of-the-art consumer decoder that
uses the latest in MPEG-2/HD digital technology. It recovers MPEG-2
input from the Multimedia Access Port (MMAP) at transprt bit streams
up to 29 Mbps. The HDD-200 outputs Master Broadcast Quality high definition
television in all major HD formats via the 4DTV digital satellite receiver.
Most televisions have a 4:3 aspect ratio, but movies are closer to 16:9.
With the HDD-200 you'll see 30% more of the whole picture, in wide screen
format. The Motorola HDD-200 offers the ability to choose a specific
output pormat including 1080i, 720p or 480p or consumers can also select
"native" as an output format, alloing the output to automatically
match whatever input is received. The HDD-200 is user friendly enough
to allow for consumer installation and includes key output features
such as analog RGB video, YPrPb video and Dolby brand AC-3 compressed
audio via a S/PDIF connection.
1.
What is HDTV?
HDTV is an acronym for High
Definition Television. HDTV was first introduced in the early 1980's
in Japan. It was known there as the MUSE system, which was an analog
HDTV storage and delivery system. MUSE had great picture quality but
required immense amounts of bandwidth for storage and broadcasting,
so it never really caught on. HDTV is now possible because of digital
encoding which allows compression of the signal to make it easier to
store and transmit. Digitally encoding a television picture is known
as DTV, or Digital Television. A signal that is DTV is not necessarily
HDTV - think of small dish systems and the digital channels on the 4DTV
system. However, all HDTV signals are DTV - or digital.
There is one additional acronym
the consumer needs to know, that is EDTV or Extended Definition Television.
EDTV is a digital television picture that is a little better than the
current NTSC (National Television Standards Committee - the formal name
of the system we all currently watch) but is not quite up to HDTV standards.
This includes such transmission schemes as 480p DVD.
2.
What's the difference between HDTV and Standard TV?
To the point - it's about
the picture and sound. HDTV offers about twice as many "lines"
of resolution and better quality, digitally encrypted five-channel sound
as well. Our current television system is more than 60 years old. It
works entirely in the analog domain, much like an AM radio receiver.
Although the ability to add color was included in the 1950's, the basic
standard for transmitting and decoding a television picture has not
changed since.
HDTV works entirely in the
digital domain and so has more in common with your computer than with
your current television set. HDTV signals are transmitted or stored
in the form of data bits. Because these data bits are stored and transmitted
with parity checking and error correcting ability, the picture is always
outstanding - as long as you can receive the data stream you will get
the best picture without ghosting, noise, sparkles or static.
In terms of what you can
see, your current television system, NTSC, is capable of a picture approaching
500 lines of resolution. That is, the system can resolve details to
1/500 the picture width. HDTV will provide you with twice that amount
of picture information both vertically and horizontally.
3.
What are aspect ratios?
The aspect ratio of a television
display or television picture describes the ratio of the pictureÕs
width to height. Current NTSC pictures are 4 units wide by 3 units tall,
nearly square. This came about because that ratio, 4X3 or 1.33:1, was
the ratio used for early motion pictures. Also called the "Academy
Ratio" for the Motion Picture Academy that established it, it was
chosen so movies could be shown on television without having to change
their basic composition and shape.
As television gained in popularity,
people found less of a reason to go to the movie theater. In response
to this decline in business, moviemakers created new aspect ratio standards
to create ever-larger images that use more of the viewer's peripheral
vision. This immersed the viewers into a "virtual reality"
experience long before that term was even coined.
HDTV, being a system designed
for the home viewing of movies and other programming, will use a wide-screen
aspect ratio that is similar to, but still a little narrower than, major
movies. Many movies are released in aspect ratios as wide as 2.20:1.
HDTV will be presented in a 16:9 format (1.77:1).
4.
Why are aspect ratios important?
Aspect ratios are part of
the cinematography of the film. Imagine what 2001, A Space Odyssey would
look like if the picture were as square as the Academy Ratio. This movie
was intended to subtend a large angle of view in order to put the viewer
into the action. The aspect ratio helps to create the effect the director
(Stanley Kubrick, in the case of 2001) envisioned. It is part of the
art of film.
It is impossible to take
all the information in a movie like 2001 and put it on a standard television
screen. If the total height of the movie screen is used (so you don’t
cut off the heads and feet of the actors) then you must "crop"
the image that falls outside of the 3X4-image area. If you use the total
width of the image, then you have black bars at the top and bottom of
the screen. This is known as "letterbox." The wide aspect
ratio of HDTV will allow the vision of the movie artists to be delivered
to your home with less compromise and greater impact.
5.
Can you explain NTSC, 1080i, 720p and native?
To understand this we must
have a basic understanding of how the NTSC system works. The following
explanation is a generalization, for the enthusiast looking for all
the details there are several good web sites which explain the complete
operation of NTSC television.
The NTSC system shows us
30 picture frames-per-second (fps) using two fields. Each field consists
of half the scanning lines of the frame. Thus, in the first 1/60 second
the television tubes illuminates odd numbered scanning lines 1-525 (there
are always 525 vertical lines, horizontal resolution is the term often
used to describe the sharpness of a TV set in "lines of resolution").
In the second 1/60 second the picture tube illuminates the even lines
(2-524). These two fields of scanning lines are therefore interlaced
at a frequency of 15750Hz. All of this is keyed to the power line frequency
(60Hz, convenient eh?) — in Europe the televisions are keyed to
50Hz.
The "i" in 1080i
stands for "interlaced" which means the picture is constructed
exactly as detailed above but at a much higher rate. Instead of using
525 vertical lines of information the 1080i system uses 1080 lines of
information. 540 lines are illuminated every 1/60 second and interlaced
with the remaining 540 lines at a frequency of 32400Hz. This faster
scanning rate, coupled with more lines of information, creates a picture
that does not exhibit the graininess, flicker and visible scanning lines
of NTSC. Further, the entire system carries with it a wider bandwidth
(bandwidth is proportional to picture detail) allowing about twice as
much information to be displayed when compared with NTSC.
The "p" in 720p
stands for progressive. Progressive scan systems operate like a computer
system; they show each scanning line sequentially without interlace.
Thus, a 720p system would posses 720 horizontal scanning lines, which
are illuminated every 1/60-second. A 720p system can be said to operate
at a frequency of 43200Hz. As the scanning frequency of a set gets higher,
the set gets more expensive and difficult to produce. This is why you
do not find too many 35" computer monitors — they can get
very expensive.
While a detailed discussion
of the merits of progressive vs. interlaced design is beyond the scope
of this document, it can be said that 1080i is currently the dominant
form for HDTV transmission and display. For the sake of flexibility,
the General Instrument HDD200 offers the user the ability to choose,
via a back panel switch, whether the system should output information
in the form of 1080 interlaced only, 720 progressive only, or "native"
(meaning what comes in is what goes out). In this way, the HDD200 will
be compatible with many combinations of programming and display device.
6. What
is the importance of having AC-3?
AC-3 is one form of Dolby
Digital surround-sound which allows the user to experience a virtual
reality of sound created with a matrix of 5 speakers and a subwoofer
(known and an Low Frequency Effects channel). Currently the 4DTV IRD
will allow the user to listen to Dolby Digital sound in monaural, stereo
and pro-logic surround sound. The HDTV protocol allows the use of true
5.1 channel AC-3 sound and the user can access this sound on high definition
channels with the addition of the HDD200 decoder.
On the surface of it Pro-logic
and AC-3 seem very similar: they both use five speakers and a subwoofer,
speaker positioning is identical, both systems offer total immersion
into the movie sound-field, wide dynamic range, and good detail.
Let us first look at Dolby
Pro-logic (which is identical to Dolby surround sound and THX in a conceptual
context). Dolby Pro-logic is a system that provides left, center, right
and surround channels from a 4-2-4 matrix. It works like this…
The sum and difference between
the two channels are used to derive the center and surround channels
algebraically. If we label the two storage channels as A and B:
A + B = center channel sound
A — B = rear channel
sound
(A + B) + (A-B) = Channel
R (right channel)
(A + B) - (A-B) = Channel
L (left channel)
Dolby AC-3, on the other
hand, is a digital encoding system that offers 5.1 discrete channels
of sound. The five channels are right front, center, left front, right
rear, left rear and a low frequency effect (subwoofer) channel. The
addition of the 1.1 channels, and the fact the system offers discrete
channels with greater separation than the matrix system described above,
allows the sound to mimic directional cues and spatial effects to a
very high degree.
7.
What is SDPIF?
SPDIF stands for Sony Philips
Digital Interface. This is an interface standard that is specified in
the compact disc "red book." The "red book" describes
in detail the workings of digital audio transmission, storage and replay
within a compact disc digital audio environment. SPDIF protocol uses
a coaxial copper cable to connect a digital audio source to a digital-to-analog
(D/A) converter or digital processor. TosLink (Toshiba) is another interface
protocol that specifies the use of a fiber optic cable between digital
components.
Most consumer audio products
that offer AC-3 sound decoding also offer an SPDIF interface. In addition,
many audiophiles and industry professionals feel that the SPDIF protocol
allows for better sound quality than TosLink. The HDD200 decoder offers
SPDIF output for connection to a digital processor or high quality external
D/A converter.
8. What
is S-Video?
S-Video is an interface protocol
that allows a video component to pass a video signal along to a monitor
or recording device in a segregated chrominance (color) and luminance
(black and white detail) format. This interface is very effective at
eliminating "dot crawl" and other picture anomalies on signals
that are received from a component quality source. If the original source
is composite (black-and-white and color information have been combined)
then the S-video connection offers essentially no advantages. Let’s
examine this.
On a digital picture, such
as the digital channels on your 4DTV IRD, the signal can be sent directly
from the programmer to your system with the color and black-and-white
information separated. This allows your monitor to display the picture
with all the fidelity possible.
If the signal is an analog
source, such as an analog VCRS or clear feed from your 4DTV, then the
color and black-and-white information have been combined at the programmer
level and must be separated again before your TV can display the image.
This separation is done by a "comb filter" located in the
television. While it is possible to add a comb filter to an analog satellite
receiver (or laser disc player, for that matter) and feed an S-Video
signal to your monitor, the question becomes which component has the
best comb filter — the monitor or satellite receiver? Since a comb
filter is present in every television, and since comb filter design
and performance are directly dependent on the requirements of the monitor,
the best comb filter is usually the one found in your television monitor.
This is especially true on modern HDTV monitors.
For best performance the
signal from an analog source should be sent to the monitor via the RCA
composite output, the signal from digital channels sent via S-Video
connection an the signal from HDTV programs via the YPrPb connections
located on the back of the HDD200 decoder.
9. What
is the difference between RGB and YprPb?
RGB stands for red, green
and blue: the base colors from which all the colors your television
monitor can display are derived. The HDD200 decoder offers RGB + sync
(horizontal and vertical sync) connections so you can use front projection
and professional quality CRT monitors to display the high definition
image.
A new interface is also supported.
This is called YPrPb (also known as 770.3) and is the HDTV equivalent
of an S-Video connector. YPrPb transmits the picture information in
a luminance and phase-opposite chrominance pair over three coax cables.
Most new HDTV monitors offer YPrPb connections.
10.
Who invented HDTV?
High Definition Television,
as we know it today, was created by a Grand Alliance of companies working
together to create the next generation of television. Members of the
Grand Alliance included General Instrument, Zenith, Sarnoff Labs (RCA),
the Massachusetts Institute of Technology (MIT) and AT&T Labs and
Philips. The Grand Alliance was formed in May of 1993 under the auspices
of the FCC and was tasked with producing a single set of standards that
would allow HDTV transmission to be phased into use in the United States.
11. When
will all my channels be HDTV?
It is very unlikely that
there will be a day when every channel is HDTV. HDTV is just one option
among many for the transmittal of television picture information. Even
though the entire television universe will likely become a digital universe
in the years to come, HDTV will be reserved for programming where extreme
picture quality is required. Many less critical programs will remain
in SDTV (standard definition television) format.
12. Will
the 4DTV and HD box ever become one?
While it is certainly possible
to combine the HDD200 and the 4DTV IRD onto a single chassis, the truth
of the matter is that most consumers will not own an HDTV compatible
display device for years to come. So long as the average consumer owns
an SDTV display it is easier and more economical to create the 4DTV-HDD200
system in a two chassis configuration. In this way you can purchase
just those capabilities you need to meet your requirements.
13. What is the difference
between small dish HD dnd C-Band HD?
Small dish programming, with
the exception of certain pay-per-view movie channels, is sourced from
C-Band originated originals. The small dish companies, like cable companies,
have C-Band reception equipment, which they use to capture the signal,
encode it, compress it, and rebroadcast it. All this signal manipulation
naturally results in compromised picture quality.
HD broadcasts will be handled
in the same manner. To provide a premium movie channel on a small dish,
the small dish programmer will capture it from the C-Band original,
encode, compress and rebroadcast the program.
14. Will the HD box make
non-HD channels look better?
When a standard definition
channel (SDTV) is processed through the HDD200 it is upconverted to
a 1080i signal. While this process does not add any more "resolution"
to the picture (you have all that you will ever have at the point of
origin) the process can make scanning lines less intrusive and give
the picture a smoother, more homogenous and film-like look.
15. What happens if I hook
the HDD200 to a non-HD TV?
It is very unlikely that
you will damage the SDTV monitor but you will certainly not get a viewable
picture. Your SDTV monitor is incapable of operating at the high scanning
frequencies required to produce an HDTV image
16. Can I use the HD 200
on a small dish system?
The answer is no. The HDD200
is expressly designed for use with 4DTV, Starchoice and certain digital
cable boxes manufactured by General Instrument.
17. My HDTV monitor is in
a basement; my 4DTV is in the living room upstairs. Can I run a long
cable between the 4DTV and the HDD200?
The MMAP (Multi-Media Access
Port) is transmitting data at a fantastic rate to the HDD200. The integrity
of this data is vital to the proper operation of your HDTV decoder.
To assure data integrity, the interlink between the 4DTV and the HDD200
must be kept to a maximum of two meters.
18. Will the HDD200 provide
off-air decoding of HDTV signals?
No. The HDD200 will decode
a digital signal and provide an HDTV image to an appropriate display
device. The HDD200, however, was designed for use first and foremost
with digital cable boxes manufactured by General Instrument Corp. With
this in mind, the HDD200 does not include an off-air TV tuner. Including
a TV tuner in a device designed to work with a cable system would be
redundant and needlessly increase the price of the unit for the majority
of users. The HDD 200 is also designed to work with the General Instrument
4DTV and other GI satellite receivers. Again, there is very little reason
to include an off-air TV tuner in a device so designed. The problem
is not one of decoding, but of getting the signal from your antenna
into the GI HDD200 for processing.
This is not the end of the story, though. The HDD200 is an "open
architecture" design like the 4DTV IRD. Because of this it can
be re-programmed via a "firmware" change. Firmware is the
operating system of the unit, much like Windows is the operating system
of a computer, and like a computer the operating system of both the
4DTV and the HDD200 can be changed and upgraded. There currently exists
a protocol which will allow the digital TV off-air tuners of other manufacturers
to "talk" with a device such as the HDD200. At a future point
it will be possible for General Instrument to include, in a new firmware
offering, the ability for the HDD 200 to accept these off-air signals.
