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Uplink and Downlink Frequencies

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Hamidzia

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Asslam O Alekum!

Regarding Satellite Communications

In C band the uplink freq is 6 GHz
and downlink freq is 4 GHz.

In Ku band the uplink freq is 14 GHz
and downlink freq is 12 GHz.

It is obvious that the uplink and downlink freqs have to be different
from each other to avoid interference.

My question is that for what reasons do u think that uplink freq is always
kept greater than downlink freq ?
 

Search the forum before post !


/pisoiu
 

i think because when there if higher frequency voltage level its needs more power, which the earth transmitters could supply
 

sattelite communications by
roger L freeman

classic book it covers aal ur queries abt ur every question regarding this type of communicatioon
i will try my level best to find this if i have time :)

take care
 

hii..
there are two reasons, both are inter-related too.
1. from ground station, u have send a high frequency, with high power;and earth station can easily have power arrangements;while in satellite, one has to save as much power as much one can!!!
2. on satellite u cannot have very large diameter antennas. so, from earth station, one has to send a narrow-beam signal, according to a small size satellite antenna.. whereas on earth station it can have upto 30feet dia antennas, to collect the signal from satellite..

both points are inter-related b/c to transmit a narrow-beam signal, one has the transmitter has to send more power also..

i think u will understand the reason now..
 
Naveed Alam said:
hii..
there are two reasons, both are inter-related too.
1. from ground station, u have send a high frequency, with high power;and earth station can easily have power arrangements;while in satellite, one has to save as much power as much one can!!!
2. on satellite u cannot have very large diameter antennas. so, from earth station, one has to send a narrow-beam signal, according to a small size satellite antenna.. whereas on earth station it can have upto 30feet dia antennas, to collect the signal from satellite..

both points are inter-related b/c to transmit a narrow-beam signal, one has the transmitter has to send more power also..

i think u will understand the reason now..
Click to expand...

And here I can possibly add that In ionosphere there comes a lot of power loss of the signals , that is why we need higher power for transmitting to satellite and receiving to ground station with respect to general low power signals ...

And I am really Kindful to Mr. Naved Alam For this good answer ....

Thank u sir.
 

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