The reason for choosing waveguides at microwave frequencies is that waveguides act as high pass filters, so when designed with proper cut-off frequency then it simply passes uplink frequency rejecting the downlink frequency (which is of no use here). Generally, waveguides are used for signal propagation through satellites. In order to make sure that the downlink signal does not enter the receiver pre-amplifier of the satellite, filters are required to be placed.
This resultantly makes the amplifier unstable. This is so because if this happens then an amplified form of uplink signal (i.e., downlink signal) will cause jamming of the weak uplink signal, due to the close presence of uplink and downlink antenna in the satellite. The uplink and downlink frequency should not be the same.The Low-frequency signal undergoes easy power amplification than the high-frequency signal.The three factors for frequency selection are as follows: A noteworthy point over here is that the uplink frequency should always be more than the downlink frequency. The frequency selection in satellite communication is a crucial aspect. The frequency of the signal which is transmitted from the earth station to the satellite is known as the uplink frequency while the frequency of the signal transmitted from the satellite to the ground is called the downlink frequency. So, uplink denotes the transmission of radio waves from an earth station to satellite and downlink corresponds to the transmission from satellite to earth station. Further, the satellite retransmits the signal towards the earth stations present on the various locations on the ground according to the respective application. We know the basics of satellite communication that signals from the ground station present on the surface of the earth is transmitted towards the satellite. When uplink is taking place then such satellite communication is referred to as Upload. The operation can be understood as Uplink denotes a link, up from earth station to satellite.
0 kommentar(er)
