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K		 Why UP-LINK frequency is greater than DOWN-LINK frequency? View All
in Satellite Communication
15 years ago - 2 months left to answer. - 3 responses - Report Abuse
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Er. amiya parida
 This is because the ground temperature of the earth which contributes to the thermal noise is large and so the frequency is increased to increase the signal to noise ratio.

15 years ago

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Theea Mohammad
 1. To mitigate the free space spreading losses, and the tropospheric losses (clouds, rain), all of which are related to wavelength and therefore to frequency (wavelength=speed of light in vacuum/frequency). In a point to point scenario (fixed wireless links) this becomes irrelevant as the difference between the forward channel and the return channel is not very large. In this case, the assignment is a consequence of the coordination studies carried on in the framework of the ITU to minimize the impact one microwave service might have upon another (satellite on fixed terrestrial, WiMax on fixed satellite, fixed terrestrial on satellite, etc).
2.There is always the intra-system interference issue, which is the interference caused in your signals by other signals transmitted by your own system. in this case, to avoid interference from site A to Site B and viceversa, a frequency channel is assigned to Site A's transmissions and another to Site B's. in this case one of them is higher in

15 years ago

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rishi trivedi
 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 theC band and/orKu band
C-band transmission is susceptible to terrestrial interference while Ku-band transmission is affected byRain fade (as water is an excellent absorber of microwaves).C band is defined as frequency band between 0.5 and 1 GHz (0.3 and 0.6 m).
The Ku band is a portion of theElectromagnetic spectrum in the Microwave range of frequencies ranging from 10 to 18 Hertz.


15 years ago

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