Question

Which of the following statements are correct?

1. The Doppler Effect must be accounted for in LEO and MEO orbits.

2. LEO satellites require frequent handovers.

3. GEO satellites suffer from significant latency and propagation delay

• A. 1 & 2
• B. 1 & 3
• C. 2 & 3
• D. All are correct

Answer 1

Answer:

D. All are correct

• Correct Answer: Option D (All are correct)

• The Doppler Effect must be accounted for in LEO and MEO orbits: This is correct.

• The Doppler Effect causes frequency shifts in signals when there is relative motion between the transmitter and receiver. Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) satellites move at high speeds relative to Earth's surface (LEO: ~7.8 km/s, MEO: ~4.2 km/s). This significant relative motion necessitates compensation for Doppler shift in communication systems to maintain reliable connections.

• LEO satellites require frequent handovers: This statement is correct.

• LEO satellites orbit at altitudes of approximately 160-2,000 km and complete an orbit in about 90-120 minutes. From a ground observer's perspective, a LEO satellite is visible for only a short period (typically 5-15 minutes per pass). Communication systems using LEO satellites must therefore constantly switch (handover) connections from one satellite to another as they appear and disappear over the horizon, ensuring continuous service.

• GEO satellites suffer from significant latency and propagation delay: This is accurate.

• Geostationary Earth Orbit (GEO) satellites orbit at approximately 35,786 km above the equator. At this distance, radio signals traveling at the speed of light take about 119.4 ms for a one-way trip between Earth and the satellite. This results in a minimum round-trip delay of approximately 239 ms, which is noticeable in real-time applications like voice calls or video conferencing, and can significantly impact performance in time-sensitive applications.