Topic: Communication Systems
A satellite orbiting in 600 km orbit transmits 5 GHz frequency. The Doppler shift observed at the ground station, when the satellite is over head of the station is
- A. Zero
- B. Maximum
- C. Infinity
- D. None of the above
Answer: A. Zero
Explanation: Doppler shift is proportional to the relative radial velocity between the transmitter and the receiver. When the satellite is exactly overhead, its motion is purely tangential to the ground station, meaning the radial velocity is zero. Consequently, the Doppler shift observed at that instant is zero (Note: The provided source key incorrectly listed 'Maximum', but physics dictates it is zero).