GNSS - GLOBAL NAVIGATION SATELLITE SYSTEMS |
VERIFIED QUESTIONS AND ANSWERS - COMPLETE
COVERAGE 2026/2027
GLOBAL NAVIGATION SATELLITE SYSTEMS (GNSS)
1. What does the abbreviation GNSS stand for?
(A) Global Navigation Satellite System
(B) Global Network Satellite Service
(C) General Navigation Satellite Survey
(D) Geographic Navigation Signal System
ANSWER : (A) Global Navigation Satellite System
Explanation: GNSS is the generic term for all satellite systems that provide
positioning, navigation and timing with global coverage.
2. Which term is used collectively for satellite systems that provide
autonomous positioning with global coverage?
(A) SBAS
(B) GBAS
(C) INS
(D) GNSS
ANSWER : (D) GNSS
Explanation: GNSS covers GPS, GLONASS, Galileo and BeiDou. SBAS
and GBAS are augmentation systems, and INS is not satellite based.
Page 1 of 50
,3. The basic principle used by GNSS to determine a receiver position is
(A) triangulation using measured angles to satellites
(B) trilateration using measured ranges to satellites
(C) dead reckoning from speed and heading
(D) magnetic bearing to ground beacons
ANSWER : (B) trilateration using measured ranges to satellites
Explanation: The receiver measures distances to satellites whose positions
are known and intersects the resulting spheres.
4. What is the minimum number of satellites needed for a three-dimensional
position fix when the receiver clock is unknown?
(A) Two
(B) Three
(C) Four
(D) Five
ANSWER : (C) Four
Explanation: There are four unknowns (x, y, z and receiver clock bias), so
four independent measurements are required.
5. The fourth satellite in a GNSS position solution is mainly needed to
(A) increase the received signal power
(B) remove the ionospheric delay
(C) identify the PRN code
(D) solve for the receiver clock offset
ANSWER : (D) solve for the receiver clock offset
Explanation: Receiver clocks are not atomic clocks, so their error is treated
as a fourth unknown.
6. Which was the first operational satellite navigation system?
(A) TRANSIT
(B) GPS
(C) GLONASS
(D) Galileo
ANSWER : (A) TRANSIT
Explanation: TRANSIT was developed for the US Navy and became
operational in the 1960s.
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,7. The TRANSIT system determined position mainly by measuring the
(A) carrier phase ambiguities
(B) pseudorange codes
(C) Doppler shift of satellite signals
(D) return time of laser pulses
ANSWER : (C) Doppler shift of satellite signals
Explanation: Users tracked the Doppler curve of a passing satellite to
compute their position.
8. NAVSTAR is the name of the US programme that produced
(A) GLONASS
(B) GPS
(C) Galileo
(D) BeiDou
ANSWER : (B) GPS
Explanation: NAVSTAR GPS is the formal name of the United States
Global Positioning System.
9. GPS was declared to have Full Operational Capability in
(A) 1995
(B) 1978
(C) 1983
(D) 2000
ANSWER : (A) 1995
Explanation: Full Operational Capability with 24 operational satellites was
declared in April 1995.
10. Selective Availability (SA) on GPS was switched off in
(A) January 1990
(B) May 2000
(C) March 1995
(D) December 2005
ANSWER : (B) May 2000
Explanation: SA was discontinued on 2 May 2000, which immediately
improved civilian accuracy.
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, 11. The purpose of Selective Availability was to
(A) encrypt the military signal
(B) correct satellite clock errors
(C) increase the transmitted power
(D) intentionally degrade the accuracy available to civil users
ANSWER : (D) intentionally degrade the accuracy available to civil users
Explanation: SA added deliberate clock and orbit errors to the civil signal.
12. A pseudorange is
(A) the exact geometric distance to the satellite
(B) the altitude of the satellite above the ellipsoid
(C) a measured range that includes receiver clock error and other biases
(D) the carrier phase converted to metres without ambiguity
ANSWER : (C) a measured range that includes receiver clock error and
other biases
Explanation: It is called pseudo because it is contaminated by clock offsets,
atmospheric delays and noise.
13. For a GPS satellite directly overhead, the signal travel time is roughly
(A) 6.7 milliseconds
(B) 670 milliseconds
(C) 67 milliseconds
(D) 6.7 seconds
ANSWER : (C) 67 milliseconds
Explanation: About 20,200 km divided by the speed of light gives roughly
67 milliseconds.
14. GNSS radio signals travel at approximately
(A) 340 m/s
(B) 3 × 10⁸ m/s
(C) 3 × 10⁶ m/s
(D) 3 × 10⁵ m/s
ANSWER : (B) 3 × 10⁸ m/s
Explanation: Radio waves travel at the speed of light, about 299,792 km per
second.
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VERIFIED QUESTIONS AND ANSWERS - COMPLETE
COVERAGE 2026/2027
GLOBAL NAVIGATION SATELLITE SYSTEMS (GNSS)
1. What does the abbreviation GNSS stand for?
(A) Global Navigation Satellite System
(B) Global Network Satellite Service
(C) General Navigation Satellite Survey
(D) Geographic Navigation Signal System
ANSWER : (A) Global Navigation Satellite System
Explanation: GNSS is the generic term for all satellite systems that provide
positioning, navigation and timing with global coverage.
2. Which term is used collectively for satellite systems that provide
autonomous positioning with global coverage?
(A) SBAS
(B) GBAS
(C) INS
(D) GNSS
ANSWER : (D) GNSS
Explanation: GNSS covers GPS, GLONASS, Galileo and BeiDou. SBAS
and GBAS are augmentation systems, and INS is not satellite based.
Page 1 of 50
,3. The basic principle used by GNSS to determine a receiver position is
(A) triangulation using measured angles to satellites
(B) trilateration using measured ranges to satellites
(C) dead reckoning from speed and heading
(D) magnetic bearing to ground beacons
ANSWER : (B) trilateration using measured ranges to satellites
Explanation: The receiver measures distances to satellites whose positions
are known and intersects the resulting spheres.
4. What is the minimum number of satellites needed for a three-dimensional
position fix when the receiver clock is unknown?
(A) Two
(B) Three
(C) Four
(D) Five
ANSWER : (C) Four
Explanation: There are four unknowns (x, y, z and receiver clock bias), so
four independent measurements are required.
5. The fourth satellite in a GNSS position solution is mainly needed to
(A) increase the received signal power
(B) remove the ionospheric delay
(C) identify the PRN code
(D) solve for the receiver clock offset
ANSWER : (D) solve for the receiver clock offset
Explanation: Receiver clocks are not atomic clocks, so their error is treated
as a fourth unknown.
6. Which was the first operational satellite navigation system?
(A) TRANSIT
(B) GPS
(C) GLONASS
(D) Galileo
ANSWER : (A) TRANSIT
Explanation: TRANSIT was developed for the US Navy and became
operational in the 1960s.
Page 2 of 50
,7. The TRANSIT system determined position mainly by measuring the
(A) carrier phase ambiguities
(B) pseudorange codes
(C) Doppler shift of satellite signals
(D) return time of laser pulses
ANSWER : (C) Doppler shift of satellite signals
Explanation: Users tracked the Doppler curve of a passing satellite to
compute their position.
8. NAVSTAR is the name of the US programme that produced
(A) GLONASS
(B) GPS
(C) Galileo
(D) BeiDou
ANSWER : (B) GPS
Explanation: NAVSTAR GPS is the formal name of the United States
Global Positioning System.
9. GPS was declared to have Full Operational Capability in
(A) 1995
(B) 1978
(C) 1983
(D) 2000
ANSWER : (A) 1995
Explanation: Full Operational Capability with 24 operational satellites was
declared in April 1995.
10. Selective Availability (SA) on GPS was switched off in
(A) January 1990
(B) May 2000
(C) March 1995
(D) December 2005
ANSWER : (B) May 2000
Explanation: SA was discontinued on 2 May 2000, which immediately
improved civilian accuracy.
Page 3 of 50
, 11. The purpose of Selective Availability was to
(A) encrypt the military signal
(B) correct satellite clock errors
(C) increase the transmitted power
(D) intentionally degrade the accuracy available to civil users
ANSWER : (D) intentionally degrade the accuracy available to civil users
Explanation: SA added deliberate clock and orbit errors to the civil signal.
12. A pseudorange is
(A) the exact geometric distance to the satellite
(B) the altitude of the satellite above the ellipsoid
(C) a measured range that includes receiver clock error and other biases
(D) the carrier phase converted to metres without ambiguity
ANSWER : (C) a measured range that includes receiver clock error and
other biases
Explanation: It is called pseudo because it is contaminated by clock offsets,
atmospheric delays and noise.
13. For a GPS satellite directly overhead, the signal travel time is roughly
(A) 6.7 milliseconds
(B) 670 milliseconds
(C) 67 milliseconds
(D) 6.7 seconds
ANSWER : (C) 67 milliseconds
Explanation: About 20,200 km divided by the speed of light gives roughly
67 milliseconds.
14. GNSS radio signals travel at approximately
(A) 340 m/s
(B) 3 × 10⁸ m/s
(C) 3 × 10⁶ m/s
(D) 3 × 10⁵ m/s
ANSWER : (B) 3 × 10⁸ m/s
Explanation: Radio waves travel at the speed of light, about 299,792 km per
second.
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