Loading presentation...

Present Remotely

Send the link below via email or IM

Copy

Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.

DeleteCancel

Make your likes visible on Facebook?

Connect your Facebook account to Prezi and let your likes appear on your timeline.
You can change this under Settings & Account at any time.

No, thanks

Cable and Satellite

Television Lecture #7
by

Drew Hamilton

on 14 April 2011

Comments (0)

Please log in to add your comment.

Report abuse

Transcript of Cable and Satellite

Cable and Satellite
Television
Birth of Cable
Cable is actually older than you might think
Birthplace of Cable
It was born in
1948
in the small town of
Lansford, Pennsylvania
, a small town 80 miles outside of Philadelphia
Father of Cable
It was started by John Walson, an appliance dealer in Lansford
Because the area around Lansford was mountainous, people had terrible reception trying to get Philly TV broadcasts…thus Walson’s TV’s weren’t selling.
His solution was to pay for a HUGE antenna to be built, then using coaxial lines he distributed the TV signals to the homes of his customers. After which he sold many TV sets and gave more service to more people.
He called this system
CATV, or Community Antenna Television
…now known as cable television
Who Needed Cable
In the early days, people who needed cable were:
People who lived in mountainous areas with valleys that made reception difficult
People who lived too far away from their closest broadcasting station
Certain people who lived in large cities where TV signals are very strong and sometimes results in ghosting
Ghosting
Ghosting
is the result of 2 broadcast images being fed through the same frequency
There are 2 types of ghosting:
multi-path reception
and
cross channel ghosting
Multi-path reception is much more common
That is where the same channel is received twice due to the signal bouncing
Multi-path
reception
Multi-path
reception
Cross Channel Ghosting
Is the result of 2 channels next to each other on the dial blending their signals and their pictures
Often a result of poor antenna reception
Much rarer than multi-path reception
What is the "cable" in Cable TV?
To fix ghosting in large metro areas, AT&T started installing
COAXIAL
cable starting in 1952
Coaxial cable is made of a copper wire surrounded by an electrical insulator. This in turn is surrounded by braided wire and metal foil shielding.
That is needed to prevent interference from broadcast waves or electrical appliances near the cable
After you have all that put together, surround it in waterproof PVC, and you have the finished cable.
Coaxial
Coaxial Problems
Although coaxial cable has been used for decades to conduct TV signals, it has a number of problems.
Topping that list is the need to constantly re-amplify signals (with the various problems that introduces) as they are sent through cables, because the signal gets weaker the further it travels. You often see CATV cables and amplifiers attached to utility poles.
The Future of Cable: Fiber Optics
The medium that is taking over from coaxial cable is
fiber optics, also called optical fiber or OF
Fiber optic cable uses
LIGHT
to transmit information instead of electricity
Because light has a much higher frequency and moves much faster, a single OF cable can theoretically carry TRILLIONS of bits of information each second.
The thickness of 1 optical fiber is only slightly large than a human hair.
Fiber optic cables normally carry numerous OF strands within a single enclosure.
10 Advantages of Fiber Optics over Coaxial
1. Much greater capacity: The information carrying capacity of OF is hundreds of times greater than a normal copper wire.
2. Low signal loss over a wide range
3. Virtually immune to all interference
4. No problems with leakage
5. No problems with temperature
6. Extremely small size
7. Will not “short out” in bad weather or even in water
8. Low maintenance costs once it's in place
9. High reliability the fibers don’t corrode or break down in moisture or salt air the way copper wires do
10. Light weight. - since they are not based on metal, they are lighter and easier to install
Why Wait?
Ok, we get it...Fiber Optics are waaaaay better than coaxial, but why don't we use fiber optic cables yet?
The answer lies below your feet
To replace coaxial with fiber optics would included ripping out cable from EVERYWHERE under the ground and putting in fiber optic cable
It's an enormous cost, that cable companies view as not worth the money
Cable Expands...IN SPACE!!!!
At first, cable was just for people who couldn't get a normal broadcast reception
But, as antennas got bigger, and cables carried signals further and further, cable’s role shifted from transmitting local broadcast signals to providing new programming choices.
The key thing that made cable boom was satellites
Before satellites, the only way you could get cable was though the giant antennas cable companies could receive broadcasts from…which wasn’t that big of an area.
Satellites hovering around 22,000 miles about the earth fixed that problem.
Satellites are how almost all TV programming is sent to world viewers these days.
Satellite Terms: Transponder
Each satellite, or “bird” has about 20-30 transponders on it.
Transponders
are independent receive-transmit units. So, each satellite can send or receive 20-30 different broadcasts at one time.
The DirecTv 8 super satellite has more than 100 transponders on it
Satellite terms: Geosynchronos satellites
Geosynchronos satellites are constantly moving in an orbit identical to the planet's orbit.
They move as the Earth moves, so in regard to where we see them...they don't move
If you have DIRECTV you get the vast majority of your programming from DirecTv 8, a satellite positioned above the Southwestern edge of the Gulf of Mexico
DirecTV 8
Around Here
23,000 miles up
Uplink
The way cable networks/satellite networks get their programming is the broadcast is fed by a
REFLECTOR

DISH
of a ground station to the satellite.
The reflector dish is shaped like a giant searchlight, so it can send a direct stream to the satellite. This is called an
UPLINK
Downlink
Once the signal is received by the satellite, the frequency is changed, the signal is amplified and it is sent back to earth.
This is called a
DOWNLINK
The reason satellite television is so valued is when a signal is sent back down to earth, its coverage area, or “
FOOTPRINT”
covers thousands of miles
DirecTv 8's footprint ranges from Puerto Rico to Alaska
Signal Received
Within the footprint area are
RECEIVING DISHES
that collect the satellite signal, which then amplifies it thousands of times and feeds it to your TV
Satellite Distribution
Networks and TV productions routinely distribute their programming via satellite…typically from LA to the East Coast for distribution
Once they arrive on the East Coast, they are recorded, commercials are added and the program is scheduled into the network schedule.
Once it is scheduled, it is then beamed back up to satellites at intervals appropriate to the time zones across North America.
When the network to affiliate link is not being used to relay regular programming, it’s used to send news stories, program promotions and other broadcast-related segments to affiliated stations.
Different news feeds from CNN, NBC and AP also come down during those times
Home Satellite TV
For people living in rural areas out of the range of local TV and CATV/cable services a satellite receiver may be the only way they can view TV.
Home satellite receivers can be cheaper in the long run than CATV/cable services and they open the door to hundreds of TV and audio channels
Early Home Satellite Systems
TV-receive only (TVRO)
satellites came onto the market in the early 80s
Those satellite TV receiver systems were largely constructed by hobbyists and engineers. These TVRO system operated mainly on the C band frequencies and the dishes required were large; typically over 3 meters (10 ft) in diameter.
Consequently TVRO is often referred to as "big dish" or
"Big Ugly Dish" (BUD)
satellite television.
The good thing about them is that the “service” was free.
The bad thing is the choices were limited, and you had to tune the satellite yourself…plus, the satellites were VERY expensive
Big Ugly
Dish
Direct-Broadcast Satellite
DBS (Direct Broadcast) or DTH (Direct to Home)
subscription services, such as Direct-TV and Dish Network came onto the market in the 90s…offering the choices of cable with small satellite receivers installed on your roof
Unlike the TVRO dishes, small dishes are constantly tuned to a set satellite owned by the satellite company
The picture quality with direct satellites tends to be better, because it is not filtered.
The dish is directly tuned to the satellite’s footprint, so you are getting your television directly from space…not stopping first at a cable TV downlink.
The downside to direct satellites is weather interference. Heavy rain or storms in your area can disrupt the signal coming in…making your picture poorer or not even come in
Cable vs. Satellite
Cable and Satellite have been battling for years over providing your television service
Since it’s not nearly as established as cable, direct satellite has fewer subscribers than cable…but satellite has gained subscribers every single year since it started
Cable has actually started to decline. Today cable systems have around 60 million subscribers (down from around 70 mill at its peak), while satellite has around 40 million
Full transcript