Month: September 2016

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PENGARUH MASSA SATELIT TERHADAP PARAMETER SATELIT LAINNYA

Massa Satelit itu tidak ada pengaruhnya dengan ketinggian. Tapi berperngaruh terhadap adanya sumber non gravitasi, seperti radiasi matahari ,adanya tekanan dari atmosfir dan juga bentuk permukaan bumi yang tidak bulat.  Karena dalam rumus kepler dijelaskan bahwa ketinggian itu berbanding terbalik dengan massa,

Dengan m = massa satelit, M = massa bumi, v = kelajuan satelit, R = jarak satelit diukur dari pusat bumi.
Sebagi contoh, satelit geosinkron yaitu satelit yang tetap berada di atas titik yang sama di atas katulistiwa. Jadi kelajuan satelit geosinkron diatur sedemikan rupa sehingga satelit tersebut mengelilingi bumi dengan periode yang sama dengan periode rotasi bumi, yaitu 24 jam. Satelit tersebut harus memiliki kelajuan sekitar 3,070 km/jam, dan mengorbit pada ketinggian 36000 km di atas permukaan bumi.

 

 

Teori Dasar Geometri Ruang Angkasa

Mempelajari masalah orbit satelit, yaitu menyatakan posisi satelit sebagai fungsi waktu dan menentukan lintasannya pada ruang angkasa, sebenarnya sama saja dengan mempelajari gerak planet-planet mengitari matahari atau bulan mengitari bumi. Kesamaan ini terjadi karena suatu satelit buatan dapat dianggap sebagai suatu satelit alam, seperti halnya planet-planet bagi matahari atau bulan bagi bumi, sehingga semua hukum gaya, gerak, kecepatan, dan sebagainya yang berlaku pada satelit alam berlaku juga bagi satelit buatan.

Pada awal abad ke -17, Kepler menemukan hukum yang mengatur pergerakkan planet yang kemudian dikenal sebagai hukum Kepler yang terdiri dari tiga buah ketentuan, yaitu:

1. Hukum Kepler I : Setiap planet bergerak mengitari matahari dengan lintasan berbentuk ellips dengan matahari sebagai salah satu pusatnya.
2. Hukum Kepler II : Juring yang dibentuk oleh lintasan planet dan matahari pada pusatnya pada selang waktu yang sama akan mempunyai luas yang sama
3. Hukum Kepler III : Perbandingan kuadrat dari periode (T) terhadap pangkat tiga dari sumbu semi mayor (a) adalah sama untuk semua planet pada tata surya kita. T² / a³ adalah konstan.

Sementara itu dari hukum Newton memperlihatkan bahwa hukum Kepler  ke II akan terjadi jika planet dipengaruhi oleh gaya tarik yang selalu mengarah ke titik pusat tertentu, yaitu matahari sebagai pusat gaya. Untuk memenuhi hukum Kepler I, gaya tersebut harus berbanding terbalik dengan kuadrat jarak antara planet dan matahari (1/r²). Akhirnya, dengan memenuhi hukum Kepler III, gaya tersebut haruslah sebanding dengan massa planet.

Hal-hal tersebut di atas dinyatakan oleh Newton dalam hukum gravitasinya dimana Newton mengangap tidak hanya matahari yang mempengaruhi planet dalam hal ini, tetapi juga setiap massa yang satu (m₁) mempengaruhi massa yang lainnya (m₂), dengan sebuah gaya yang arahnya sepanjang garis hubung antara kedua massa tersebut dan besarnya gaya (F).

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Joel Andri Prasetya Saragih ( 1101124341)

 

(Telecommunication Engineering)

 

*What does Satellite Communications mean?*

Satellite communications is the use of satellite technology in the field of communications. The services provided by satellite communications are voice and video calling, internet, fax, television and radio channels.

Satellite communications can provide communication capabilities spanning long distances and can operate under circumstances or conditions which are inoperable for other forms of communication.

 

 

#The Main Advantages offered by Satellite Communication :

-> Cost Effectiveness – Cost of satellite capacity does not increase with the number of users/receive sites, or with the distance between communication points. Whether crossing continents or staying local, satellite connection cost is distance insensitive. b.

-> Global Availability – Communications satellites cover all land masses and there is growing capacity to serve maritime and even aeronautical markets. Customers in rural and remote regions around the world who cannot obtain high speed Internet access from a terrestrial provider are increasingly relying on satellite communications.

-> The satellite can form the star point of a communications net, simultaneously linking many users who may be widely separated geographically.

-> The same feature enables satellites to provide communications links to remote communities in sparsely populated areas that are difficult to access by other means.

-> Satellites are also used for remote sensing, examples being the detection of water pollution and the monitoring and reporting of weather conditions

 

#Distance-Insensitive Communication System :

it costs about the same to provide a satellite communications link over a short distance as it does over a large distance. Thus a satellite communications system is economical only where the system is in continuous use and the costs can be reasonably spread over a large number of users.

 

#The Comparison beetween Satellite Communication & Optical Fiber Communication System

 

#Satellite VS Optical Fiber :

1.  Optical Fiber is quicker but Satellite is slow in communication.
2.  Optical Fiber higher bandwidth but Satellite Lower Bandwidth.
3.  In case of any fault we can easily repair Fiber Optics but Satellite can not be repair.
4.  Fiber Optics initial Cast is low but Satellite is very High.
5.  Many People want to communication during jogging, driving, sailing and flying these all possible in Satellite Communication But Fiber Optics not use for them.
6.  Satellite cost low for long range communication, while optical fiber is very costly for long range communication.
7. Minimum three or four satellite can cover the whole world, Fiber optics can also do that but cost considerations are to be worked out (possible with solition communications only).
8. Satellite provide global mobile communication, for example, GPS. For optical fiber, there is no possibility of mobile terminals since cable is to be laid physically.
9. Satellite is more suitable to the rough terrain and remote areas where fiber optics and microwave can’t be used.
10. Satellite suffers from propagation delay. For optical fiber, no such delays.

 

#The Development of SKSD PALAPA  & The Evolution

1) First generation
a. Palapa A1 (8 June 1976)
b. Palapa A2 (10 March 1977)

2) Second generation
a. Palapa B1 (19 June 1983)
b. Palapa B2 (6 February 1984 – Failed), replaced by B2P
c. Palapa B2P (20 March 1987)
d. Palapa B2R (20 March 1990)
e. Palapa B4 (7 May 1992)

3) Third generation
a. Palapa C1 (1 February 1996)
b. Palapa C2 (16 May 1996)

In 2009, Indosat launch Palapa D, which it has lifetime until 2010 or 2011.
Telkom also launch Telkom-1 on 16 November 2005 to replace Palapa B4. Until now, Telkom has launched three satellites, Telkom-1, Telkom-2, and Telkom-3 (failed), and the next Telkom will launch Telkom 3S to replace Telkom-3 which has failed to orbit.

#The Development of INTELSAT

In 1965, Intelsat established the first commercial global satellite communication system named
INTELSAT-1 or Early Bird, and then INTELSAT has launched several satellites, such as:
a. INTELSAT-16 (Febuary 2010)
b. INTELSAT-17 (November 2010)
c. INTELSAT-28 (October 2011)
d. INTELSAT-22 (March 2012)
e. INTELSAT-19 (June 2012)
f. INTELSAT-20 (August 2012)
g. INTELSAT-21 (August 2012)
h. INTELSAT-23 (October 2012)
i. INTELSAT-30 (October 2014)

 

#The Meaning of : S/N, C/No, Eb/No, dB, dBm, dBW, and dBmo :

a. S/N : is a measure used in science and engineering that compares the level of a
desired signalto the level of background noise.
b. C/No : is a measure used in science and engineering that compares the level of a
desired signal to the level of background noise.
c.  Eb/No : the energy per bit to noise power spectral density ratio
d.  dB : decibel, expresses the ratio of two values of a physical quantity, often power or
intensity
e.  dBm : power relative to 1 milliwatt
f.  dBW : power relative to 1 watt.
g.  dBmo : decibels relative to 1mW at point of zero reference level