it-e-15 Simple Introduction to VSAT

What is VSAT ? VSAT stands for Very Small Aperture Terminal//it's a catchy acronym

and as such it's been adopted by all and sundry for every type of satellite product from small
components of a system to complete systems. Because the term really hinges around the small size
of the antenna it has been used to describe both one-way and interactive systems. Specifically, we
in the industry, isolate television broadcast receivers because counting these as well would simply
distort the numbers in the marketplace, but data, audio and, to some extent, voice systems are
included. Generally, these systems operate in the Ku-band and C-band frequencies. As a rule of
thumb C-band (which suffers less from rain attenuation, but requires larger antennas) is used in
Asia, Africa and Latin America whilst Ku-band (which can use smaller antennas, but suffers from
rain fade in a monsoon-like downpour) is used in Europe and North America. Typically, interactive
Ku-band antenna sizes range from 75 centimetres to 1.8 metres and C-band from 1.8 metres to 2.4
metres. One way systems can use antennas as small as 45 centimetres.
What does a network look like? VSAT networks come in various shapes and sizes ranging
from star data system users with one site connected to an operator's shared hub to many
thousands based on a dedicated facilitylocated at their own site. Mesh systems have traditionally
been somewhat smaller in size than star systems//5 to 30 sites used to be a good rule of thumb
- but the average size of orders has risen as prices have come down and some rural telephony
networks now comprise as many as several hundred or even thousands of sites.
What is One-way Satellite ? One way systems rely on a transmitting station which
transmits one or more carriers to the satellite which re-broadcasts the signal over its coverage
area. All receive-only VSATs under the satellite footprint can then receive the signal or the
user/operator is able to define groups of VSATs from one to all on the network. Broadcast
systems are used for data and audio. The most popular application for data is the transmission of
financial feeds//Reuters, Telerate and KnightRidder are good examples of companies with
large data broadcasting networks//however, there are many other uses, such as software
downloads, file transfers, transmission of press agency news items (with pictures) and the
broadcast of paging messages for terrestrial transmission to the pagers themselves.
Who uses VSAT ? You name it really, car dealerships, gas stations, lottery systems, banks,
insurance companies, drug stores, general stores, supermarkets, healthcare companies, manufacturers,
couriers, hotel chains, car rental businesses, food manufacturers, heavy industries, mines, electrical
utilities, oil and gas pipelines, energy production and exploration, timbercompanies, plantations,
various government departments and agencies ... any others you can think of, just add to the list.


aperture ['æpə,tjuə] 英汉翻译

n. 孔,穴;缝隙;(照相机,望远镜等的)光圈,孔径

catchy ['kætʃi] 英汉翻译

adj. 引人注意的;容易记住的;易使人上当的

acronym ['ækrəunim] 英汉翻译

n. 首字母缩略词

sundry ['sʌndri] 英汉翻译

adj. 杂的;各式各样的n. 杂货;杂项

1, hinges   
n. 铰链;合页(hinge的复数);小五金
v. 给…装上绞链;使以…为条件(hinge的第三人称单数形式)
2, antenna  [æn'tenə]
n. 天线;触角,触须
3, distort  [dis'tɔ:t]
vt. 扭曲;曲解;使失真
vi. 扭曲;变形
4, frequencies   
n. 频率(frequency的复数形式);频数分析;次数分配表
5, attenuation  [ə,tenju'eiʃən]
n. 衰减;变薄;稀释
6, hinge  [hindʒ]
n. 铰链;枢纽;关键
vt. 给…安装铰链
vi. 依…而转移
7, monsoon  [mɔn'su:n]
n. 季候风;(印度等地的)雨季;季风
8, downpour  ['daunpɔ:]
n. 倾盆大雨;注下
9, dedicated  ['dedikeitid]
adj. 专注的;献身的;专用的
v. 以…奉献;把…用于(dedicate的过去式和过去分词)
10, facility  [fə'siliti]
n. 设备;灵巧;容易;设施
11, mesh  [meʃ]
n. 网眼;网丝;圈套
vi. 相啮合
vt. 啮合;以网捕捉
12, terrestrial  [ti'restriəl, tə-]
adj. 陆地的,陆生的;地球的;人间的
n. 陆地生物;地球上的人
13, dealership  ['di:ləʃip]
n. 代理权;代理商;经销权
14, timber  ['timbə]
n. 木料;木材

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