Transcript Document

DoubleVision Television
Department of Electrical and
Systems Engineering
ABSTRACT
Television has been an excellent medium for entertainment and
information ever since the invention of the electron scanning tube in
1923 by Vladimir Kosma Zworykin, who is considered the father of
the modern television. Unfortunately, people sharing a television are
forced to watch one channel at a time or use a different television if
they want to watch different programs. As a result, there are often
arguments about which channel to watch. There is currently no system
that allows viewers in the same room to view different channels
without the use of multiple televisions. Present day systems such as
picture-in-picture (PIP) are largely ineffective as they only use a small
fraction of the screen area for the secondary channel, and there is no
way of hearing the audio from that channel.
The goal of this project was to design a system that solves these
problems. The DoubleVision Television (DVTV) system comprises
of a NTSC processing unit that allows two groups of viewers to
simultaneously watch different channels on the same television. Two
groups of viewers can use shutter glasses with built-in polarization
properties to differentiate and watch two different channels. The two
sound signals from the two different channels are separated and
transmitted to the appropriate user via a wireless headphone system.
1. NTSC SIGNAL
5. VIDEO MULTIPLEXING
The NTSC standard for television defines a composite video signal with a
refresh rate of 59.94 fields (half-frame) per second (approximately 60Hz).
Each frame contains 525 lines stacked horizontally. A field is a set of even
lines, or odd lines. The odd and even fields are displayed sequentially about
ever y 1/60 of a second, thus interlacing the full frame.
The two synchronized channels are passed into the video multiplexing stage.
Using the sync signal from the control unit, the two channels are interlaced.
The output of the multiplexer becomes a single field-sequential NTSC signal
with the odd and even fields representing channel A and channel B
r e s p e c t ive l y. T h e o u t p u t r e t a i n s t h e N T S C s i g n a l s t r u c t u r e.
A mixer box [DVTV Box] was built to interlace two separate channels
that can be displayed on any standard CRT TV. First, two analog NTSC
signals of the viewers’ choice are extracted from the multi-channel
frequency band coming from the cable provider or any video source
such as VCR or DVD. The sound signals are simultaneously separated
and sent to the RF transmitter which transmits the two separate sounds
to two separate headphones. Then, the two video signals are
synchronized using a time base correction unit. These two separate
synchronized NTSC channels are interlaced by a video multiplexer
2. CHANNEL EXTRACTION
circuit. The timing signal is extracted and used to control this video
multiplexer. The output of the multiplexer becomes a single fieldIncoming NTSC signal (from cable provider, stored media or antenna) is split
sequential NTSC signal with the odd and even fields representing
into two. From each of these signal streams, a desired channel is extracted
channel A and channel B respectively. The same timing signal is used to
using a TV tuner (TUN-181). The sound signals are simultaneously
control the shutter glasses, which turn ON and OFF at the right time
separated and sent to the Dual Channel RF Sound transmitter.
to give two viewers two completely different channels.
PRESENTERS
Nii Ayite Ayite EE ’05
Zereyacob Girma EE’05
Aung Naing EE ’05
GROUP 9
DEMO TIMES
Thursday, April 21st, 2005
11:30AM, 1:00PM, 1:30PM and 3:00PM
6. DISPLAY
The single stream of interlaced fields, which is in NTSC format, is fed into a
standard CRT TV. Two complementary sync signals generated by the
control unit trigger the glasses ON and OFF at the appropriate moment.
The two TV signals coming out of the TV tuners are out of phase. These
signals are synchronized by a time base correction unit. As a result, both of
t h e d e s i r e d c h a n n e l s h a v e i d e n t i c a l v e r t i c a l s y n c s i g n a l s.
7. SHUTTER GLASSES
Dr. Kostas Daniilidis
Dr. Nader Enghetta
SPECIAL THANKS TO
Mr. Sid Deliwala
Dr. Shih-Schon Lin
9. RESULTS AND CONCLUSIONS
3. TIME BASE CORRECTION
ADVISORS
4. TIMING EXTRACTION
The ver tical sync infor mation is
extracted from the tuned, synchronized
channels and passed on to the control
unit. The control unit uses the vertical
sync to generate sync signals to control
the video multiplexer unit as well as the
switching of the shutter glasses.
8. CIRCUIT PICTURE
The operation of the
shutter glasses is such that if
no electric field is applied,
all light can pass through
(ON) and if electric field is
applied, all light is blocked
(OFF). The light coming
out of a normal CRT TV is
unpolarized and hence
suitable for the operation of
the shutter glasses.
• Two separate channels can be successfully watched by two
groups of viewers.
• This DVTV box can be used with any NTSC CRT TV.
• Whilst each viewer is watching a 30Hz channel, the loss in
quality due to the slower refresh rate is minimally noticeable
to the average viewer. In other words, while there is a drop in
quality in comparison to a regular TV, the viewing condition is
more than satisfactory.
• The use of 120Hz television will improve quality giving
each viewer 60Hz.
• TV screens with better response times will result in the
optimal quality.
• With the use of 120Hz TVs, the system could potentially be
extended to four channels with 30Hz for each channel.
• The DVTV box can be manufactured cost-effectively.
• Potential applications include home theater, cinema,
airplane and video gaming.
GROUP 9
GROUP 9