Telecommunications Satellite Communications 1 — Questions and Answers
Question 1: What does GEO stand for in satellite communications?
- Global Earth Orbit
- Geostationary Earth Orbit (Correct answer)
- General Equatorial Orbit
- Ground-based Earth Operations
Correct answer: Geostationary Earth Orbit
GEO stands for Geostationary Earth Orbit, where satellites orbit at approximately 35,786 km above the equator and remain stationary relative to Earth.
Question 2: At what approximate altitude do geostationary (GEO) satellites orbit Earth?
- 2,000 km
- 20,200 km
- 35,786 km (Correct answer)
- 100,000 km
Correct answer: 35,786 km
GEO satellites orbit at approximately 35,786 km above Earth's equator, which produces an orbital period of exactly 24 hours, matching Earth's rotation.
Question 3: Which satellite orbit provides the lowest signal latency for communications?
- GEO (Geostationary Earth Orbit)
- MEO (Medium Earth Orbit)
- LEO (Low Earth Orbit) (Correct answer)
- HEO (Highly Elliptical Orbit)
Correct answer: LEO (Low Earth Orbit)
LEO satellites at 500–2,000 km altitude provide the lowest latency (~20–40 ms) because signals travel much shorter distances compared to MEO or GEO.
Question 4: The C-band frequency range used in satellite communications covers approximately:
- 1–2 GHz
- 4–8 GHz (Correct answer)
- 12–18 GHz
- 26–40 GHz
Correct answer: 4–8 GHz
C-band covers approximately 4–8 GHz and is widely used for satellite communications due to its resistance to rain fade and long-established infrastructure.
Question 5: What is the primary advantage of Ku-band over C-band for satellite communications?
- Less susceptible to rain fade
- Smaller receive antenna size required (Correct answer)
- Better penetration through building walls
- Lower path loss in clear sky conditions
Correct answer: Smaller receive antenna size required
Ku-band's higher frequency (12–18 GHz) produces shorter wavelengths, allowing smaller dish antennas, which makes it practical for consumer satellite TV services like DirecTV.
Question 6: A transponder on a communications satellite is designed to:
- Generate the satellite's primary electrical power
- Receive, amplify, frequency-convert, and retransmit signals (Correct answer)
- Control satellite attitude and orbital station-keeping
- Manage onboard telemetry and computing functions
Correct answer: Receive, amplify, frequency-convert, and retransmit signals
A transponder receives the uplink signal, amplifies it, shifts it to a different downlink frequency, and retransmits it toward Earth, acting as a relay in space.
Question 7: The round-trip signal delay for a communication path through a GEO satellite is approximately:
- 10–20 milliseconds
- 50–100 milliseconds
- 240–280 milliseconds (Correct answer)
- 500–600 milliseconds
Correct answer: 240–280 milliseconds
A GEO satellite is ~35,786 km away; a round-trip signal travels roughly 143,000 km at the speed of light (~300,000 km/s), resulting in about 240–280 ms of latency.
Telecommunications Satellite Communications 1
What does GEO stand for in satellite communications?