Affiliated to Tribhuvan University

Nayabazar, Khusibun Development AreaTel: 4360180, 360182E-add: - pcmit@wlink.com.npURL: - www.prime.edu.np

Report on Visit to Sagarmatha Earth Station.

Submitted By: - Submitted To: -Geshan Manandhar - “03-00097-2”Geshan Manandhar - “03-00097-2” Manoj SinghManoj SinghSabin Man Malla – “03-00103-2”Sabin Man Malla – “03-00103-2” Lecturer, HSMNLecturer, HSMNSachin Rai– “03-00104-2”Sachin Rai– “03-00104-2” Prime CollegePrime CollegeSmriti Singh – “03-00113-2”Smriti Singh – “03-00113-2”BIM 7th Semester BIM 7th Semester Prime CollegePrime College

Date of Submission: - Date of Submission: - 1111 thth March 2007 March 2007

Satellite Communication:

A communications satellite (sometimes abbreviated to comsat) is an artificial

satellite stationed in space for the purposes of telecommunications. Modern

communications satellites use geosynchronous orbits, Molniya orbits or low polar Earth

orbits. Most of the satellites deployed are used to facilitate better communication some

are put for research as well.

For fixed services, communications satellites provide a technology

complementary to that of fiber optic submarine communication cables. They are also

used for mobile applications such as communications to ships and planes, for which

application of other technologies, such as cable, are impractical or impossible.

Satellite Communication Applications:

Some of the sectors where satellite communication services have been used are

listed below:

1. Telephony

2. Satellite Television and Radio

3. Mobile satellite technologies

4. Satellite broadband

1. Telephony: The first and still, most important application for communication

satellites is in international telephony. Fixed-point telephones relay calls to an

earth station, where they are then transmitted to a geostationary satellite. An

analogous path is then followed on the downlink. In contrast, mobile telephones

(to and from ships and airplanes) must be directly connected to equipment to

uplink the signal to the satellite, as well as being able to ensure satellite pointing

in the presence of disturbances, such as waves onboard a ship.

Hand held telephony (cellular phones) used in urban areas do not make use of

satellite communications. Instead they have access to a ground based constellation

of receiving and retransmitting stations.

SES, Balamboo Report- HSMN © GSSS 20071

2. Satellite Television and radio: Satellite television and radio makes it possible

that we see the numerous television channels in our homes everyday. Satellite

radio in our country hasn’t caught any hype but it can be the next big thing as in

India the advent of World space radio has lifted some eye brows.

In the US, there are two satellite types used for North American television and

radio:

a. Direct Broadcast Satellite (DBS), and

b. Fixed Service Satellite (FSS).

A direct broadcast satellite is a communications satellite that transmits to small

DBS satellite dishes (usually 18 to 24 inches in diameter). Direct broadcast

satellites generally operate in the upper portion of the Ku band. DBS technology

is used for DTH-oriented (Direct-To-Home) satellite TV services, such as

DirecTV, DISH Network, and Sky Angel in the United States, ExpressVu in

Canada, and Sky Digital in the UK, Republic of Ireland and New Zealand.

Fixed Service Satellites use the C band, and the lower portions of the Ku bands.

They are normally used for broadcast feeds to and from television networks and

local affiliate stations (such as program feeds for network and syndicated

programming, live shots, and backhauls), as well as being used for distance

learning by schools and universities, business television (BTV), video-

conferencing, and general commercial telecommunications. FSS satellites are also

used to distribute national cable channels to cable TV head ends.

FSS satellites differ from DBS satellites in that they have a lower RF power

output than the latter, requiring a much larger dish for reception (3 to 8 feet in

diameter for Ku band, and 12 feet on up for C band), as well as using linear

polarization for each of the transponders' RF input and output (as opposed to

circular polarization used by DBS satellites). FSS satellite technology was also

originally used for DTH satellite TV from the late 1970s to the early 1990s in the

United States in the form of TVRO (TeleVision Receive Only) receivers and

dishes (also known as big-dish, or more pejoratively known as "BUD" or "Big

ugly dish" systems). It was also used in its Ku band form for the now-defunct

Primestar satellite TV service.

SES, Balamboo Report- HSMN © GSSS 20072

3. Mobile satellite technologies: Initially available for broadcast to stationary TV

receivers, by 2004 popular mobile direct broadcast applications made their

appearance with that arrival of two satellite radio systems in the United States:

Sirius and XM Satellite Radio Holdings. Some manufacturers have also

introduced special antennas for mobile reception of DBS television. Using GPS

technology as a reference, these antennas automatically re-aim to the satellite no

matter where or how the vehicle (that the antenna is mounted on) is situated.

These mobile satellite antennas are popular with some recreational vehicle

owners. Such mobile DBS antennas are also used by JetBlue Airways for

DirecTV (supplied by LiveTV, a subsidiary of JetBlue), which passengers can

view on-board on LCD screens mounted in the seats.

4. Satellite broadband: In recent years, satellite communication technology has

been used as a means to connect to the Internet via broadband data connections.

This can be very useful for users who are located in very remote areas, and cannot

access a wireline broadband or dialup connection. It can be a viable solution for a

country like our but the cost can be sky high.

SES, Balamboo Report- HSMN © GSSS 20073

Sagarmatha Satellite Earth Station

Address: Balabmoo, Kathmandu, Nepal

Established: 1982 (Working from 1985)

Visit Date: 7th February 2007

Briefed By: Er. Niraj Barjracharya, NTC

Earth stations are mainly placed to facilitate communication between

geographically far terminals via communications satellites. The earth stations

comprises of relevant dish antennas, control over the antennas and in modern context

proper software and computers for full control and even to provide communication

via backup resources in case of failure of primary link.

Sagarmatha Earth Station Balamboo has three Satellite dishes with no specific

names so lets term them as A,B and C. All the three satellites are of the world’s

largest commercial satellite communications services provider IntelSat. and their

specifications are tabulated below:

# Standard Disk

Size

Band, Transfer rate Satellite is facing “Indian

Ocean Region” at

A A 16 m C Band, 35 db/K 60 ° East

B B 11 m C Band, 31 db/K 64 ° East

C B 9 m C Band, 31 db/K 66 ° East

A typical C-band works at 6 Ghz uplink and 4 Ghz downlink but a Ku band works

at 11 Ghz uplink and 14 Ghz downlink. Satellite communication mainly depends on

the line of sight so antennas/dishes should be placed in the precise position so that the

communication is efficient.

Satellites face the Indian Ocean Region as it is hard to point to the Pacific or

Atlantic region as informed by Mr. Bajracharya. He adds that Satellites run on solar

power chiefly but also has battery backup for power. Battery’s power is limited but life

span is of 10-15 years. Satellites also have frequency and bandwidth limitation as other

forms and mediums of communications. Use of 60 ° angle makes it possible to see 1/3 of

the earth so it is very effective.

SES, Balamboo Report- HSMN © GSSS 20074

He subsequently informs that the bandwidth of satellites is very costly and use of

sophisticated devices further escalates the cost. The bandwidth is given as per demand

but costs are very high.

As per him, antennas are passive devices but play a vital role in communication.

They have a transmission gain of 56 db. He clarifies that the primary uses of the earth

station are as follows:

1. NTC web browising

2. All international voice calls via NTC’s terminals

3. Data circuit

4. Occasional TV (Live Broadcasting or video clips broadcast)

5. Domestic satellite trunk service

6. VSAT network support

He bluntly tells that the satellites provide no support for satellite phones.

The antenna control is digital, except of one dish which has to be moved physically.

Use of branded PCs from Sun Microsystems Ex: Sun Ultra 2, Sun Black 1000 and

some Dell machine ensure hardware reliability and stability. On the contrary, use of

Windows in most of the system seems insecure and only some of the systems had full

proof OS like UNIX. The software used seemed very complicated. The switches and

connections were very informative as it we came to know it was the backbone of our

STD and ISD.

SES, Balamboo Report- HSMN © GSSS 20075