Q8Satellite Communication
Question
Q.8. What is meant by perigee and apogee?
Answer
The main components used in an earth station are the antenna, Low Noise Amplifier (LNA), High Power Amplifier (HPA), up-converter and down-converter, modem (modulator/demodulator), and tracking/control system.
The components used in a satellite communication earth station include: the antenna (parabolic reflector, for both transmit and receive), the Low Noise Amplifier (LNA, amplifying the weak received downlink signal with minimal added noise), the High Power Amplifier (HPA, such as a TWTA or SSPA, boosting the uplink signal to the power level needed for reliable satellite reception), up-converters and down-converters (frequency translation between the baseband/IF signal and the RF uplink/downlink frequency bands), the modem (performing modulation of the outgoing signal and demodulation of the incoming signal), and the antenna tracking and control system (maintaining accurate antenna pointing toward the satellite, particularly important for non-geostationary satellites or where high-gain, narrow-beamwidth antennas are used).