Satellite Communication

Introduction
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Satellite ?????? ???????????? telecommunication ??????? ??????????? ??????????????? ???? ?? ???????? Mobile application ????????????? ????.. ???????? ? ?????????????? ????????? ?????????? ????????? TV/Radio ?????????????? ?????????????? ???????? ?????????????????? ?????????? ??? ??????????????????????? ?????????????
1) Weather Forecasting
2)Radio and TV Broadcast
3)Military Purpose
4)Navigation
5)Global Telephone
6)Connecting Remote Areas
7)Global Mobile communication ??? ???????????????????
8) Internet ????????

???????? ???? ?????????? services ?????? ???????????? ?????????????? ????????????? ????? ?????? ??????????? ? Satellite ???????? ?????????????? ???? ??? ????????????????? Coverage area ??? Footprint ???? ??????????????? ?????????????? ?????????? ??????????????? Footprint ??? ????????????? satellite ??????? ??????? ?????????????? ???????? ????????????????? ????? ???? ??????????? ???????????????? Footprint ???????? ??????????? ????? satellite ??? power ????????????? bandwidth ??????? ???????? ??????? ??????????? ????????? ??????????????? ?????????? ?????? Ground Station ??? ??????? ????????? ??????????????
Satellite ????? ?? ????????????? ????? ???????? Focused ????????????? Data Transmissions ?????? ??????????????????????????? ????? Focused ?????????? ?????????? ???????????? ??? ???????? ????????????? ????? ???????????? ?????????? Frequency Spectrum ??? ?????? ????? ????????? ?????? ?????????? ?????? ????????????
Satellite ??? Antenna ????? ???? ?????????? ?????????????????????????? ?????????????? ???????????? ???????????????????????? Design ????????????????????????? Satellite ???????????? design ?? ?????? ???????????????? ????? ? ?????? ??????????????? ????? ??????????? ??????????????????????? ????????????

 

Satellite ????? ?????? ?????????????
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Satellite ????? ???????? ??????????? ??????????? Microwave Repeater ?????????? Transponder ???????????? ??????????????? ????????????? ????? ?????? Satellites 750 ???????? ???????????????????????????? ????????? ???????????????????????????? Communication ??????? ?????????? ???? ??????????????? communication ???????? ????????????????????? ????????????? ???????????????? ???????? Satellite Communication ?? ???????????????????? ??????????? ?????? ????????? ?????????? Footprint Area ??? Satellite ?? Relay ????? ????????????? Point to Point (or) Point to Multi-point ???????????????? ????????? ???????????????????? ????????????????? ??????? ??????????? station ???????? ???? ???? ???????? ????????????????? ? ?????????????? satellite ??? ??????????? ???????????? ?????????? ?????????????? Station A ?? Satellite ???? Transmission ??? Uplink ??????????? Satellite ??? Transponder ?? convert ???????????? ????? Station B ??? signal ????????????????? ???????? Downlink ???? ?????????
Satellites ????? ?????????? ????????????? ???? ?????????? ??????????? ???????????????? ??????? ???????????? (?????????) ?????? ????? ???????????????? ???????????? ??????????? satellites ?????? ??????? ???????? ????? ????????????? ????????????????????? ???????? ???????????????? ??????? ??????? ???????? ?????????? ???????????????? ????????????? ?????? ????? ???????? ??? ????????????????????
Fg (attractive force) = m.g.(R/r)2 (gravity equals)
Fc (centrifugal force) = m.r.w2 (Trying to pull satellite away equals)
Variables ???????? �.
m = mass of satellite
R = radius of earth ; R=6,370 km
r = distance of satellite to the center of the earth
g = acceleration of gravity ; g =9.81 m/s2
w = angular velocity ; w=2pf ; f is the frequency of rotation;
??????????????
Satellite ???????? ??????? ??????? ????????????? ??????? ??????????? ????? Fg=Fc
?????????? ??????????? ?????? ???????? ????? ????? ??????????????????? r = distance of satellite of ther center of the earth ??? ????????? formula ????? r=(g.R^2/(2pf)^2 ) 1)/3 ????????????????? rotation frequency ????? ??????????????????? ??????????? formula ??????????

 

Type of Satellites base on orbits
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Satellite ????????????? ?? ?????????? ????????? ???????? ????????? ???????????????????? ??????????? ???????? (?) ????? ??????????????????

1) Geostationary or geosynchronous earth orbit (GEO)
2) Low Earth Orbit (LEO satellites )
3) Medium Earth Orbit (MEO satellites)

?) Geostationary or geosynchronous earth orbit (GEO)
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GEO satellites ????? ????????????? ???????? ?????????? ????? ??????? ???? ??? ??????????????? ???????????????? ?????????????? ??????????????? ????? ???????? ????????? ??????????? ????????? ?????????????????? GEO Satellite ???????? footprint ?? ??????????? ??.? % ??????? GEO Satellites ?????? ?????? ???????????????????? Coverage ??????? ?????????????????? ????????? ???????????? ?? ?????????????? ???????? ??????????? ? ?????????? ??????????????? ??????????? ????????? ???????????? ????????????????? ???????? ??????????????? ?????????? ??????????? GEO ????? ????????? ????? ??????????????? ?? ??? ? ??????? ????????? ??????????? ???????? ???????????????????? ?????? ??????????? ??????????? ????????????? ?????????????? ???? ????? ????? ??? ??????????????????? ???????????? ??????????? ? ?????? ??????????? ??? ????????? ?? ??? ? ???? ??? ?????? ?????????? ???? ?????????? ????????? ????????? ???????? ???????????? ?????? ???????????? ??????????????????????? ??????????? ????????? Satellite ??? ?????????????? ????????? TV/Radio ???????????????? ? ???????? ????? ????????????????? ?????????????? ????????? Telephone Networks ?????? Backbones ??? ???????? ?????????????????? ?
?????? ??????????????????? ???????????? ????????? (Low elevation) ??? ?????? Signal ??????????????? ????????????????????????? ???????????? ??????? ???????????????????? coverage ?????????? ?????????? ??????????? ???????????? ???????????????? ???????? ?? ???????? ???? ?????? ??????? ?????????????????? ?????? ????????????? ???????? ????????????? ?????????? GEO ?????? Mobile Phones ?????? ???????????? ?????????????????????????? ???????? Transmit ???????? Battery Power ??????????????????????? ?????????????????? Signal ???????? ?????????? ?????? ??????????????? ????? ????????????? ????????? Delay ????? ????????????? ????????????? Special Antenna ?????????? ????????? ???????????????????

  

Low Earth Orbit (LEO satellites )
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LEO ????? ??????? ??????????????? ????????? ??? ?? ???? ?????? ??????????? ?????? Lower orbit ??? ???????????? satellite ???????????????? ????????? ???????????? 95 -120 ??????????? ????????????? ?????? ?????????????? ?????? ?? ????? ??????????? ????? ????? ????????????? ??? ????? LEO Sat ??????? ??????????????????? ???????? High Elevation ???????????? ????????? ??????????????????? ??????? High quality communication link ???? ??? ???????? ??????????
???????? ??????????????????? Data Compression Schemes ????????????????????? 2400 bit/s ??????????? ??????????? ??????????????? ????? ??????????? Compression ??????? ????????????? LEOs ????? Omni-directional (????? ?????????? ???????? ?????? ????? ??? ?????? ?????????? ?????????) ?????????? Mobile Phone Devices ???? ?????? ????????????? ??????????? ?????? ??????????????? ??????????? ???????????? Transmit Power 1W ?? ??????????????? ????????? ?????? Delay rate ????? 10 ms ?? ??????????? ?????? Long-distance wired connection (delay 5-10) ????????? ????????? ???????????????????????? Footprint ??? ?? ???????????????? frequency ??? ????????????????????? ????????????????????????? Cellular Network ?????? ????????????? ???????????????????? LEOs ????? GEOs ??? ?????????????????? ??????????????? ?????? ?? ????????????????????????? ??????? ??????????? ??????????????? ??? ?????? ????????????????????
LEO Satellites ?????? Remote sensing ??? Mobile communication ???????? ???????? ???? ?????????????
???????????????????? ??????? ????????????????? ??????????????????? ???????????? ???????????????? Footprint ?????? ???????????????? Global Coverage ???????? LEOs ??? ???????????????? ??? ?????? ?????????? Global Coverage ???????? ISL (inter satellite link ) ???????? ????????????? LEOs ??????????? Routing Function ???????? interconnecting ????????????????? ???????? ???????? ???????????????? ???????????????? ????????? LEOs ?????? ????????? ??????????????? ??????????????? ??????? ?????????? ? The inner Van Allen belt1(????????? ????????????? Post ??? ???????? ??????? ???????? ? ??? ?????????????????? http://www.britannica.com/EBchecked/topic/622563/Van-Allen-radiation-belt ) ??? Radiation ????????????????? ??????????????? ? ?????? ? ???? ??????? ??????????? ?????????????????? LEO Satellites ?? ?????? ?????????? ? ???? ?????????????????? ??????????? ??????????? ??????????? ??????????? ???????????? ?????????????? ???????????? ?? ????????????? ??????????? ? LEOs ??? Data Routing ????? ?????????????????????????????? ? ???????????????? ?????????????? GEO ????? Footprint ???????????????? ??????????????? Routing ?????????? ??????????????? Sender ??? Receiver ? Footprint ???????????? ????????????????????

 

Medium Earth Orbit (MEO Satellites)
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MEOs ????? GEO ??? LEO ??????? ??? ????????? ???????????????? ????????????? ??????????????? ????? ??????????? ????????????????? MEOs ????? ?? ???????????? global coverage ????????????? ???????? GEO ??? ???????? ?????????? LEO ??? ????????????????????? ??? (????????? ????????????????????? GEO,LEO ??? MEO ??? ?? ?????????? ??????????? ????? ????????? ??????????? ??????????? ???????????????? Global coverage ?????????? ??????????????? ?????????????) ??????? ??????????????? ?????????? ??????????? ??? ??????? ?????????????? ?????? ????????????????? ??????? (Inclination) ??????? ???????? ?????????????? ???????????????? ????????? ?????????? ????? ? ?????? ???????????? ????????? ???? ???????????? ?????????????? ????????? Routing ??????????? ????????????? ???????????????? ??????????? LEOs ??? ??? ???????? ?????????????? Delay rate ????? ???????????? ? 70 ??? 80 ms ????????? ????????? ????????????????? Transmit Power ?????????? ? Footprint ????????? ??????? ??? special antenna ????????????



Orbits ?????????

 
  

Radio Frequencies for space communication
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Introduction

Satellite ??? Spacecraft (?????????)??? ????????????? ??????????????????? ?? ???????? ????????????????????? ??????? ??? ????????? ??????????? ?????? Relay ????????? ? ?????? ?????? ?????????????????????? ??????????????? ??????????????????? ????? Communication ?? ????????? ?????????????? ????? Communicate ?????????? ????????????????? ??????? ????????? Optical Communications ????????????????? ? Electromagnetic Spectrum ???????????? Radio ??? ?????????????????? ?????????? ????????????????? ?????? ???????????????????????????? ?????????????????? ??????????? ????????????? ????????? ????????????????? Radio Spectrum ???? ????????????????
International Telecommunication Union (ITU) ? ????????????? Frequency Allocation Table ??? (www.itu.int) website ???????????????????????????? ITU ? ??????????? ????????????????????????? Region III ??? ???????? ?????????????? ??????????? Australian Communications and Media Authority (ACMA) (www.acma.gov.au) ??? ???????????????????????????? Spectrum Graphic ?????? ????????????????????? ITU ??????? ?????????????????????????????????
The Electromagnetic Spectrum

??????????????? ???????????? (?) ???????????????? ????????? ??????????????????
1) The nuclear strong force
2) The electromagnetic force
3) The nuclear weak force
4) The gravitational force
???????????????? ????????? nuclear ??? ?????????? ??????? ?????? ?????????????? ?? ??????????? ???????????? ???????? ????????? ?????????? ??????????????? ????????????? ??????????????? ?????????????? ??????? ??????????? ????????? ? (nuclear bomb ?????????? ?????????? ?????????????..????)..? ??? gravity ??? ?????????????? electromagnetism ?????? ???? ????????? ???? ??????????? ????????????????
??????????? ????????? (Gravity) ??????? mass (??????) ?????? ???????? ??????? ? ????????????????????????????? (Electromagnetic) ?????????????? ??????? (Charge) ??????????????? (????) ???????????????? ??? ???????????????? ?? .. ??????????????? (Charge) ??? ????????? ????????? ???????????? ??????? ?????????????? (Electrostatic Field) ???????????????? ??????? ??? ???????? ???????????? ???? ???????????? (Constant Velocity) ???????? ?????????????????????? Charge ??? (Magnetic Field) ????????????????????? ??????? ??????????????? ???????? ?????? ???????????? ??????????????????? ???????????????? Electromagnetic Radiation ??? ???????????????????






 The Radio Spectrum
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?????? ??????????? ??????????? Radio Spectrum ??????????????????? Radio Spectrum ????? Electromagnetic Spectrum ??? ???????????? ?????????? 1Hz ??? 3000 GHz (or) 3THz ?????? ?????? Range ??????????? 3000 GHz ???????????? Infrared Spectrum ?? ????????????????? ?????? ?????????????? ?????? Frequencies ??? ?????? ?????????????????????? ??????????? ???? ????????????? ??????????? ????????????? ???? ????????????? Radio Spectrum ??? Bands ??? ????????? ????????????????
?????? ????? ????????????? ???????????????? ????????? UHF / VHF ?????????? ???????????????? ???????? frequency ??? ??????????????????? ??????????????? (f) ??? frequency ??? ?????????? (?) ??? wavelength ??? ??????????????
Frequency (f) ????? ????????????????????? ??????????????? signal ??? ??????????????? ?????????? ????????? ???????? ????????????
Wavelength (?) ????? ????????????? ?????????????? signal ??? ?????????? ???????????? ?????????????????????
Frequency ??? Wavelength ???? ?????????? theory ????? f = c / ? ???
C ?????????? EM ??? velocity ??? c = 3 x 108 ???
?????????????????? frequency ??? ?????????? Hertz (Hz) ????????????? wavelength ??? ?????????? metres (m) ??? ????????????

 

The Radio Spectrum ( ???? )
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???? post ? ???????????? ?????? ???????????? Lower Frequencies ?????????? ULF ??? ELF ?? (1Hz to 100 Hz )?????????? ???????? ?????????? (1 Hz) ??????? ?????????????? ?????? ?????????????? ?????????????? ULF ??? 1Hz ??? ?????? band ???????????????
Microwave ????? wavelength less than 30 cm ???????????? Range ??? ?????????????? ??????? New generation microwave ??? ?????????????? Region ???????????? ??????????? frequency bands ??? ??? schemes ??? ?????????? ????????????????? Traditional Microwave scheme ????? space communication ??? ???????? ??????? ????????????? Generation ?????? ??????????????????

??? ?????? ???????? band ?????? ????????? ?????????? frequency ??????? ?????????????????????

???????? Band ??? ?????????? ??????? ?????????? ??????? ??????????????????????

 

????????? ????????? (windows to space)
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Electromagnetic Spectrum ???????? ????????? ??????? ????????????? ??????????? ?????????????????? (????) ???????? ??????????????? ???? ??????????? ????????????? ?????????? ??????????? ? ???????? UV ??? frequencies ????????????????? ???????????????? ?????????? ???????????? ????????? ?????????????? ?????????
????????? EM spectrum ??? ????? ( visible light ) ??? radio spectrum ?????? ?? ????? ??????????? ??????????????????? ????? ????????????? ??????????? (Windows to space )???? ?????????????? ??????? radio spectrum ??? ???????????? ??????????????? ??????????? 30 MHz ??? 30 GHz ?????? ?? ??????????????????
30 MHz ??? ??????? Ionosphere ?????????? ??????????? ???????? ?????????? ?????? ? ???????? ?????? ??? ????????? ???????? ?????????? ??????????????? ??? ?? ??? ?????? ?????????????? 30 GHz ??? ????????????? ??????? ???????????????????? troposphere ??????????????? ??????????????? ?????????????? ????????????? ???????????????? ? 20-30 GHz ???????????? ?? ?????????????? ?????????????



Space Communication Bands ????????????
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????????????? Bands ?????? ???????? space communication ??? ???????????????? ???????????????? End device band ????????????????????? ?????????????? frequencies ?????? ??????????????? ??????????????????

VHF Bands
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VHF ????? ????????????????? short distance ?????? line of sight ?????? ??????????????????? short distance ????????? ?????????? ???????????????????? ionosphere ??? atmospheric noise ??? ???????? lower frequencies ?????? ???????????????????????? ????? ?????????????? ????????????? ??????????????? ???? ?????????????????? ?????? ???????????? ??????????? ??????????????????? ??????????? ? reflection ?????????????

(136-138 MHz)
?????????????????? Satellite type ???????????????? ????? ?? Band ??? ???????????????? ????????????? ??????????? ??? ???????????????????? Meteorological Satellite ???????? resolution ?????????? ???????????????? mobile satellite receiver ???????? data ??????????? ???????????????? ??????????????

(144-146 MHz)
??????????????? amateur satellite ??? ????? ???????????????? ?????? ??????????? band ????? 145-146 MHz ????????????

(148-150 MHz)
?? band ????? ????????????????? downlink 136-138 MHz ??? uplink band ??????????

(149.95 -150.05 MHz)
Satellite ?????????????? ? ?????? ? ????? frequency services ?????? ?????????? GPS ????????????????? US ??? Russia ??????? ??????????????????????????????? ?????? ???????????????????? Doppler effect ??????? ?????????????????? Doppler effect ????? Austrian ??????? Christian Doppler ? 1892 ??? ????????????? ????????????? ?????????? ?????????????????????? frequency ??? wave ??????? ??????????????????? ???????????? ???????? satellite ????? 400 MHz ? signal ????????????????? ?? 150 band ????? ??????? ??????????????? ???????????? ????????????? ?????????

(240-270 MHz)
????????? ???????? satellite communication ??? ??????? band ??? ????????? ??band ??????????? (225- 380 MHz) ??? ????????????? ????? ?????? ?????????????????????? ?????? ???????????????



space communication bands ???????????? ( ????)
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UHF
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UHF ??? ??????????????? ?????????????????? ??? VHF ??? Line of sight ??????????? ????????? ??????????????? signal bounce ????? ?????????????????? ???????????? Walki-Talki ??? ? TV and Radio transmission ?????? ??????????? ???????????????? ???????? ???????????

UHF TV signal ?? ionosphere ?????????????????????????????????? ????? reflection ???????? ??????????????????????????? VHF ????????????????????????? ??????????????? skip distance ???????????? ? ???????????????

UHF ?? wavelength ?????? ???????????? frequency ???????????????? ??????????????????????? ????? radio wave ?????????????????? UHF ?????? ?????? ???????? ??? ?????????????????????????? ????????? ??????????? Frequencies ????????? ??? ?????????? ????? ????????????

(399.9-403 MHz)
?? band ?????? navigation , positioning , time and frequency ???? ????????????????? mobile communication (???? ???????????) ??? ???????? ???????? ??????? ?????????????? ?? band ??? 400 MHz ?? 150 MHz ? ?????????????? ?? ????????????????????

(432-438 MHz)
??????????????? satellite ???? ???????????????

(460-470 MHz)
??????????? ??????????? ???????????????????? ????? uplink frequency ??????????
UHF band range ?? ?????????????? TV Radio Broadcasting , Cordless , Walki-talki ???? ????? ????????? ?????????????????? ????????? ??????????? ??????????? ?????????????????????????????????

???? ? ????????????????????????? ?????????? ?????????????????( Wikipidia ?? ???????????????)
� 225�420 MHz: Government use, including meteorology, military aviation, and federal two-way use[6]
� 420�450 MHz: Government radiolocation and amateur radio (70 cm band)
� 433 MHz: Short range consumer devices including automotive, alarm systems, home automation, temperature sensors
� 450�470 MHz: UHF business band, General Mobile Radio Service, and Family Radio Service 2-way "walkie-talkies", public safety
� 470�512 MHz: TV channels 14�20 (also shared for land mobile 2-way radio use in some areas)
� 512�698 MHz: TV channels 21�51 (Channel 37 used for radio astronomy)
� 698�806 MHz: Was auctioned in March 2008; bidders got full use after the transition to digital TV was completed on June 12, 2009 (formerly UHF TV channels 52�69)
� 806�824 MHz: Public safety and commercial 2-way (formerly TV channels 70�72)
� 824�851 MHz: Cellular A & B franchises, terminal (mobile phone) (formerly TV channels 73�77)
� 851�869 MHz: Public safety and commercial 2-way (formerly TV channels 77�80)
� 869�896 MHz: Cellular A & B franchises, base station (formerly TV channels 80�83)
� 902�928 MHz: ISM band, amateur radio (33 cm band), cordless phones and stereo, radio-frequency identification, datalinks
� 929�930 MHz: Pagers
� 931�932 MHz: Pagers
� 935�941 MHz: Commercial 2-way radio
� 941�960 MHz: Mixed studio-transmitter links, SCADA, other.
� 960�1215 MHz: Aeronautical Radionavigation
� 1240�1300 MHz: Amateur radio (23 cm band)
� 1452�1492 MHz: Military use (therefore not available for Digital Audio Broadcasting, unlike Canada/Europe)
� 1575 MHz: GNSS L1 band�GPS, GLONASS, Galileo
� 1710�1755 MHz: AWS mobile phone uplink (UL) Operating Band
� 1850�1910 MHz: PCS mobile phone�order is A, D, B, E, F, C blocks. A, B, C = 15 MHz; D, E, F = 5 MHz
� 1920�1930 MHz: DECT Cordless telephone
� 1930�1990 MHz: PCS base stations�order is A, D, B, E, F, C blocks. A, B, C = 15 MHz; D, E, F = 5 MHz
� 2110�2155 MHz: AWS mobile phone downlink (DL) Operating Band
� 2300�2310 MHz: Amateur radio (13 cm band, lower segment)
� 2310�2360 MHz: Satellite radio (Sirius and XM)
� 2390�2450 MHz: Amateur radio (13 cm band, upper segment)
� 2400�2483.5 MHz: ISM, IEEE 802.11, 802.11b, 802.11g, 802.11n Wireless LAN, IEEE 802.15.4-2006, Bluetooth, Radio-controlled aircraft, Microwave oven, ZigBee



Space communication bands ???????????? ( ????)
==================================
C bands
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C Band ?? ?????????????????? ?????????????? ?????????????? ??????? ?????????? .
C Band ??? ????? ??????????? (Compromise Band) ?????????? Ku Band ??? ????????????? ??????????????? microwave range 4 to 6 GHz ??? ???????????????? ??????????? ?????????????????? ?????? standard downlink frequency ? 3.7 - 4.2 GHz ???????? uplink frequency ????? 5.9 � 6.4 GHz ?????????? C Bands ??? Long distance radio telecommunications ??? ??????? ????????????? C Band ???????????? frequency ????????? wifi devices ??? ? cordless phone ??? ? weather radar system ??? ??? ????? satellite communications ??? ????????????? C Band ?? Ku Band (11.2 � 14.5 GHz) ??? ??????? ????????????? ????? ????????? ?????????? ???????????? satellites communication ??????????????????? ???????????????? ??????? ??? ????????????? ?????????????????????????? ? ?????????? ?????????? ???????????????????? ??? ?????????? ???????????????????

C Band ?????????????????? ????????????? ?????? (NATO C band ) ??? frequency 500 MHz � 1000 MHz ????????? ?????????????????? ??? Electronic Countermeasure (ECM) ?? ?????????????????? wavelength ? 0.6 m - 0.3 m ??????????? ???????? ??????? ITU ? IEEE ????? UHF Band ??????????? ???????????????????? ?????????????????? ????????? ?????????????? ??????????? ????????? ???????????

?????????????????? IEEE C-Band ??????? ???????????? 4 � 8 GHz ???????? ???????? C Band ????? satellite ? ?? ?????????? commercial ??????????? ????????????? ???????????????????? band ??? C band ?? ???? ???????????????? S band ??? overlaps ??????????? ?????????

????????? ?????? ????? ???????? ??????????? ????????? ? ????? ???? 7.5 � 12 ?? ????? ????? consumer ?????? ???????????????????????? ??????????????????? ??????????????? ????? ????????? GEO satellite ??? ????? Signal ?? ???????????? attenuation ? 200 dB ????????????????? ???????????????????? signal ??????????? ???????? C Band ?? ?????? ??????????????????? parabolic curvature type ??????????? ??????????????????????? ???????? ????????????? ??????????? ???????????????? ?????????????? ????? signal ????? microwatts ??????????????????? ???????????? ????????????????? signal ?????? Low noise amplifier (LNA) ? ???????? ????????????? noise ??? ??? ???????????????????? Kelvin ??? noise temperature ??????table ??????? ????????????????? ????????? bipolar transistors ??? ????????? amplification ??????????????

???????????? ????????????? ????????? ?????????? ????????? ??????????????? ???????????? VSAT ????????????? reliable ?????????????????????? ??????????????? (VSAT ??????????? ??????? post ????? ??????? ?????????????????? ) ?
?????.. ???????????????????? fiber optic communication ?????? c band ?? wavelength 1530 � 1565 nm ??? ?????????????????? ?????? ?????? ?????????????????? EDFAs fiber amplifiers ??? ??? ???????????

 


COPY BY 
Satellite Communication Facbook

???????????????? ?????????? ????????????? ????????? Satellite Communication Facbook
?? ?????????? ???? ???????????? ??????????????? ??????

????????????????? ??? Myanmar Satellite Station ?? ????????????????.....