![]() The Ku band is a portion of theElectromagnetic spectrum in the Microwave range of frequencies ranging from 10 to 18 Hertz. Hence the transmitted power should be higher for a higher frequency signal. 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 bandĬ-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 attenuation of the signals increases with the frequency. Again, FDMA divides the frequency bandwidth of the 25 MHz (maximum) in each direction (uplink and. 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 uplink and downlink bands are separated by 45 MHz. 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, 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).Ģ.There is always the intra-system interference issue, which is the interference caused in your signals by other signals transmitted by your own system. Why down link frequency is more than up link in GSM If you mean why is the downlink frequency higher than the uplink frequency, its because - all other things. 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. 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). ![]() 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.ġ.
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