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# Satellite Communications/Downlink vs uplink frequency in satellite communication

praveen wrote at 2008-09-26 20:37:14
this is specify already i m agree with that...................................................................................................................thanks with regard praveen

rajeshgupta wrote at 2008-11-25 10:42:36
see we have two factors here

one we require the signal strength that penetrate the atmosphere and we also require narrow beamwidth to receive the signal properly at the satellite small sized antenna these both factors are of high frequency signal that is the reason we use high frequency signal

now power we require at the earth station is also veryy high than at the satellite beacuse the output of the satellite amplifier is fixed and we have to compensate the atmospheric losses at uplink and downlink so we need more power at the earth station as it can't be produced at the satellite. and the power requirement will be based on the atmospheric condition if the whether is good power require is less and if there is rainy season the power requirement is high.

d richardson wrote at 2010-05-29 16:06:23
I believe the correct answer is a follows. The greatest single constraint on the design of a comsat spacecraft / satellite is the cost of getting its mass into orbit. This in turn limits the amount of power that the sat. can generate in orbit. This power is used most effectively if the satellite transmitter for the downlink is at the lower of the two frequencies because RF amplifiers are more efficient at lower frequencies.

anu wrote at 2011-07-21 06:49:12
as power is the limitation at the satellite and as power is directly proportional to freq we use uplink as more than downlink.........because at earth station we can generate as much power as we needed but this is not possible at satellite so the uplink that is from earth sation to satellite isusually taken more than downlink

SPITM,Institute. wrote at 2015-07-22 09:06:49
Uplink Frequency:-uplink fequency is the frequency,which is transmit from the earth to the satellite.

Downlink Frequency:-Downlink frequency is the frequency,which is transmit from the satellite to the earth.

Satellite Communications

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#### Luis Emiliani

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Strengths - Satellite link design and analysis - Vsat network design and analysis - Propagation aspects for terrestrial and satellite links - ITU-R P recommendations Can not help with: - Questions related to TV receivers, TV kits, or specific networks such as DirecTV or DISH - Antenna pattern synthesis, RF MoM analysis, S-parameters.

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