[this is a pretty good overview of satellite basics]
http://www.juiceenewsdaily.com/1004/news/sat.html?1130291973937
Satellite Television 101
(JND) - Satellite television is television delivered by way of
communications satellites in highly-elliptical (with inclination of
+/-63.4 degrees and orbital period of about 12 hours) or geostationary
orbit 37,000 km (22,300 miles) above the earth’s equator. The first
satellite television signal was relayed from Europe to the Telstar
satellite over North America in 1962. The first national network of
television, called Orbita, was based on principle of using of
highly-elliptical Molniya satellite for re-broadcasting and delivering
of TV signal to ground down-link stations. The Orbita was created in
Soviet Union in 1967. The first domestic North American satellite to
carry television was Canada’s Anik 1, which was launched in 1973. The
first Soviet geostationary satellite to carry television, called Ekran,
was launched in 1976.
Satellite television, like other communications relayed by satellite,
starts with a transmitting antenna located at an uplink facility. Uplink
satellite dishes are very large, as much as 9 to 12 meters (30 to 40
feet) in diameter. The increased diameter results in more accurate
aiming and increased signal strength at the satellite. The uplink dish
is pointed toward a specific satellite and the uplinked signals are
transmitted within a specific frequency range so as to be received by
one of the transponders tuned to that frequency range aboard that
satellite. The transponder 'retransmits' the signals back to Earth but
at a different frequency band (to avoid interference with the uplink
signal), typically in the C-band and/or Ku-band. The leg of the signal
path from the satellite to the receiving Earth station is called the
downlink. A typical satellite has 12 to 20 transponders each with a 36
to 50 Mbit/s bandwidth. Each geo-stationary C-band satellite needs to be
spaced 2 degrees from the next satellite (to avoid interference). For
Ku-band the spacing can be 1 degree. This means that there is an upper
limit of 360/2 = 180 geostationary C-band satellites and 360/1 = 360
geostationary Ku-band satellites. C-band transmission is susceptible to
terrestrial interference while Ku-band transmission is affected by rain
(as water is an excellent absorber of microwaves).
The downlinked satellite signal, quite weak after travelling the great
distance (see inverse-square law), is collected by a parabolic receiving
dish, which reflects the weak signal to the dish’s focal point. Mounted
on brackets at the dish's focal point is a device called a feedhorn.
This feedhorn is essentially the front-end of a waveguide that gathers
the signals at or near the focal point and 'conducts' them to a
low-noise block downconverter or LNB. The LNB converts the signals from
electromagnetic or radio waves to electrical signals and shifts the
signals from the downlinked C-band and/or Ku-band to the L-band range.
Direct broadcast satellite dishes use an LNBF, which integrates the
feedhorn with the LNB. (A new form of omnidirectional satellite antenna,
which does not use a directed parabolic dish and can be used on a mobile
platform such as a vehicle, was recently announced by the University of
Waterloo.)
The L band signal, now amplified, travels to a satellite receiver box
through, typically through coaxial cable (RG-6 or RG-10, etc.; cannot be
standard RG-59). The satellite receiver then converts the signals to the
desired form (outputs for television, audio, data, etc.). Sometimes, the
receiver includes the capability to unscramble or decrypt; the receiver
is then called an Integrated receiver/decoder or IRD.
Analog television distributed via satellite is usually sent scrambled or
unscrambled in NTSC, PAL, or SECAM television broadcast standards.
In general, digital television, including that transmitted via
satellites, are generally based on open standards such as MPEG and DVB-S.
The encryption/scrambling methods include BISS, Conax, Digicipher
Irdeto, Nagravision, PowerVu, Viaccess, Videocipher, and Videoguard.
There are three primary types of satellite television usage: reception
direct by the viewer, reception by local television affiliates, or
reception by headends for distribution across terrestrial cable systems.
Direct to the viewer reception includes direct broadcast satellite or
DBS and television receive-only or TVRO, both used for homes and
businesses including hotels, etc.
Direct broadcast via satellite:
Direct broadcast satellite, (DBS) also known as "direct to home" is a
relatively recent development in the world of television distribution.
“Direct broadcast satellite” can either refer to the communications
satellites themselves that deliver DBS service or the actual television
service. DBS systems are commonly referred to as "mini-dish" systems.
DBS uses the upper portion of the Ku band.
Modified DBS systems can also run on C-band satellites and have been
used by some networks in the past to get around legislation by some
countries against reception of Ku-band transmissions.
DBS systems are generally based on proprietary transport stream encoding
and/or encryption requiring proprietary reception equipment. Service
providers sometimes license several manufacturers to provider equipment
capable of receiving the proprietary streams. This equipment typically
uses a smart card as part of the decryption system orconditional access.
This measure assures satellite television providers that only
authorised, paying subscribers have access to Pay TV content but at the
same time can allow free-to-air (FTA) channels to be viewed even by the
people with standard equipment available in the market.
Satellite television by continent and country
United Kingdom:
The first commercial DBS service, Sky Television, was launched in 1989
and served customers in the United Kingdom, providing 16 analogue TV
channels. In the following year BSB was launched, broadcasting five
channels in D2Mac format; the two services subsequently merged to form
British Sky Broadcasting. In 1994 17% of the group was floated on London
and U.S. stock exchanges, and Rupert Murdoch’s News Corporation owns a
35% stake.
By 1999, following the launch of several more satellites (at 19.2°E by
SES Astra, the number of channels had increased to around 60 and BSkyB
launched the first subscription-based digital television platform in the
UK, offering a range of 200 channels broadcast from the Astra satellites
at 28.2°E under the brand name Sky Digital. BSkyB’s analogue service has
now been discontinued, with all customers having been migrated to Sky
Digital.
United States:
Consumer satellite television reception in the United States began in
the early 1980s with the introduction of the first home satellite
systems designed for receiving the same TVRO signals used for
distribution to cable systems. Early setups were very expensive and
large, with 12-foot (3.7 m) dishes common. Many were motorized, allowing
for reception from multiple satellites, and therefore a greater
selection of channels. Originally, all channels were available in the
clear, including premium movie services, a major draw and source of
growth for the then-burgeoning industry. In 1986, movie channel HBO
encrypted their signal, setting a precedent for most other mainstream
cable television services. This led to a major decline in the sales of
satellite systems. By the early 1990s, the industry recovered as a
result of Videocipher decoders being bundled with systems. TVRO systems
reached their peak around 1995 before declining as a result of consumer
adoption of higher-powered, "small-dish" systems such as DirecTV,
Primestar, and the Dish Network. As of May 31, 2005, 215,076 big dishes
were still subscribed to pay TV programming 1, as opposed to nearly
three million at the peak in 1995, although more may be in use solely
for free-to-air television reception.
Hughes’s DirecTV, the first high-powered DBS system, went online in 1994
and was the first North American DBS service; it is now owned by News
Corporation. In 1996, EchoStar’s Dish Network went online in the United
States and has gone on to similar success as DirecTV’s primary
competitor. In 2004, Cablevision’s Voom service went online,
specifically catering to the emerging market of HDTV owners and
afficianados, but folded in April 2005, with the service’s “exclusive”
high-definition channels currently being migrated to the Dish Network
system. Commercial DBS services are the primary competition to cable
television service, although the two types of service have significantly
different regulatory requirements (for example, cable television has
public access requirements, and the two types of distribution have
different regulations regarding carriage of local stations).
The majority of ethnic-language broadcasts to North America are carried
on Ku band free-to-air; the largest concentration of ethnic programming
is on Intelsat Americas 5 at 97° W. Globecast World TV offers a mix of
free and pay-TV ethnic channels in the internationally-standard DVB-S
format, as do others. Several U.S.-English language network affiliates
(representing CBS, NBC, ABC, PBS, Fox, WB, i and UPN) are available as
free-to-air broadcasts, as are the three U.S.-Spanish language networks
(Univisión, Telefutura and Telemundo). The number of free-to-air
specialty channels is otherwise rather limited. Specific FTA offerings
tend to appear and disappear rather often and typically with little or
no notice, although sites such as LyngSat do track the changing
availability of both free and pay channels worldwide.
Canada:
In Canada, the two legal DBS services available are Bell Canada’s
ExpressVu and StarChoice. The CRTC has refused to license American
satellite services, but nonetheless hundreds of thousands (if not
millions) of Canadians access or have accessed American services —
usually these services have to be billed to an American address and are
paid for in U.S. dollars. Whether such activity is grey market or black
market is the source of often heated debate between those who would like
greater choice and those who argue that the protection of Canadian firms
and Canadian culture is more important.
Most recently as of 2004, an October 2004 ruling by judge Danièle Côté
of Québec has determined the Canadian radiocommunication act to be in
direct violation of the Canadian Charter of Rights and Freedoms; the
judgement gave the federal government a one-year deadline to remedy this
breach of the Constitution as the fundamental law of the land.
In addition, Canadian satellite providers continue to be plagued by the
unquestionably black market devices which "pirate" or "steal" their
signals as well as by a number of otherwise completely lawful devices
which can be reprogrammed to receive pirate TV.
One cable TV CEO (Karl Péladeau of Québecor, which owns Vidéotron) is on
public record as demanding conditions be placed on the CRTC license
issued to Bell ExpressVu, due to BEV’s reputation for vastly inferior
security compared to its cable rivals and Shaw Cable–owned StarChoice.
Although there are no official statistics, the use of American satellite
services in Canada appears to be declining as of 2004.
Some would claim that this is probably due to a combination of
increasingly aggressive police enforcement and an unfavourable exchange
rate between the Canadian and U.S. currencies. As the U.S. dollar has
been declining as of 2005 versus other international currencies, the
decline in DirecTV viewership in Canada may well be related not to a
cost difference as much as to the series of smart card swaps which have
rendered the first three generations of DirecTV access cards (F, H and
HU) all obsolete.
Australia and New Zealand:
Satellite television in Australia has proven to be a far more feasible
option than cable television, due to the vast distances between
population centres. The first service to come online in Australia was
Galaxy Television, which was later taken over by Cable Television giant
Foxtel, which now operates both cable and satellite services to all
state capital cities and the Southwest. Its main metropolitan rival is
Optus Television, while rural areas of the Eastern States are served by
Austar. In neighbouring New Zealand, SKY Network Television now offers
multichannel digital satellite TV, in addition to its terrestrial UHF
service.
Europe:
In Europe, DBS satellite services are found mainly on the Hotbird
(operated by Eutelsat) and Astra satellites, with Sky Italia, Canal
Digitaal, Viasat, and UPC being the main providers in Italy, Western
Europe, Scandinavia, and Central Europe. BSkyB (known as Sky Television)
also serves Northern Europe and many channels can be received as far
away as Cyprus. The overall market share of DBS satellite services in
2004 was 21.4% of all TV homes, however this highly varies from country
to country. For example, in Germany, with many free-to-air TV-stations,
DBS market share is almost 40%, and in Belgium and the Netherlands, it’s
only about 7%, due to the widespread cable networks with exclusive content.
Japan:
The two satellite systems in use in Japan are B-SAT and JSAT; the BS
digital service uses B-SAT, while SKY PerfecTV! uses JSAT.
India:
After more than a decade of debate and controversy, two networks were
allowed to start Direct To Home (DTH) services in India, private
broadcaster Zee Network and state owned broadcaster Doordarshan started
Dish TV and DD Direct+ respectively.
Due to several issues concerning competitors in the Cable TV space, Dish
TV has not been able to garner the number of subscribers it had expected
to win over from Cable TV because Zee Network’s competing broadcasters
have refused to allow Dish TV to telecast their channels on the DTH
platform. With legislation coming into place and the regulating
authority TRAI working on the issue, this is expected to change soon.
Dish TV uses the NSS 6 satellite for telecast.
In 2005 Rupert Murdoch owned STAR TV Network got into an alliance with
one of the largest industrial houses (TATA) and has secured a license to
launch their our DTH platform. Similarly Anil Ambani has shown interest
in this business when one of his group companies Relience Energy also
applied for a DTH license. The licensing terms and conditions can be had
from, the official website of Ministry of Information and Broadcasting,
Government of India
India uses satellite television extensively for education. The Indian
Space Research Organization (ISRO) launched a satellite (EDUSAT) in 2004
dedicated exclusively to education. The state governments of Gujarat,
Madhya Pradesh, Karnataka, Orissa, Rajasthan and Kerala, the Indira
Gandhi Open University (IGNOU), State Open Universities and NGOs like
SEWA are regular users of EDUSAT.
Latin America:
Latin America’s main satellite system is SKY Television, which has up to
one million subscribers in Brazil, Colombia and Mexico. In 2004, DirecTV
Latin America was converted to SKY Latin America by News Corporation.
Africa:
Multichoice is the satellite for both South Africa and sub-Saharan Africa.
Television receive-only:
Television receive-only, or TVRO, refers to satellite television
reception equipment that is based primarily on open standards equipment.
This contrasts sharply with direct broadcast satellite, which is a
completely closed system that uses proprietary reception equipment. TVRO
is often referred to as "big dish" satellite television.
TVRO systems are designed to receive analog satellite signals from both
C-band and Ku-band satellite television or audio signals. TVRO systems
tend to use larger rather than smaller satellite dish antennas, since it
is more likely that the owner of a TVRO system would have a C-band-only
setup rather than a Ku-band–only setup. Additional receiver boxes allow
for different types of digital satellite signal reception, such as
DVB/MPEG-2 and 4DTV.
Parabolic Earth Station antennas receive signals from a single satellite
at a time. Simulsat is a quasi-parabolic satellite earthstation antenna
that is capable of receiving satellite transmissions from 35 or more C-
and Ku-band satellites simultaneously.
Direct broadcasting satellites which can be received by what are known
in Chinese as little ears have had a major role in breaking the
government monopoly of information on Mainland China. Although met with
frequent and generally unsuccessful efforts to regulate them, these
small satellite dishes are fairly common in urban China. Satellite
television has also played an important role in broadcasting to
expatriate communities such as Arabs, and overseas Chinese.
--
Dishnut-P
====================================================================
Operator of RadioFree Dishnuts - Producer of The Dishnut News
heard Saturdays at 10pm EST. on
RFD, W0KIE Satellite Radio Network AMC-7 Transponder 5 / 6.8 & 7.5Mhz
(4DTV W-7 973), WTND-LP 106.3, and many micro LPFM stations.
http://dishnuts.net
RFD Listen Links: http://dishnuts.net/#Listen
Show Archives: (Partly Up) http://dishnuts.net/archive/
------------------------ Yahoo! Groups Sponsor --------------------~-->
Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page
http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/EyMolB/TM
--------------------------------------------------------------------~->
Community email addresses:
Post message: mailto:[email protected]
Subscribe: mailto: [EMAIL PROTECTED]
Unsubscribe: mailto:[EMAIL PROTECTED]
List owner: mailto:[EMAIL PROTECTED]
Shortcut URL to this page:
http://www.groups.yahoo.com/group/TVRO
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/TVRO/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
