CONS 127 ACTUAL EXAM PAPER 2026
COMPLETE QUESTIONS AND SOLUTIONS
GRADED A+
◉ History of GPS
Answer: -Developed by military in 1973
- Operational in 1995 24 -Satellites
- Many people started using it in 1996 Civilian asset in 2000
◉ How many segements are needed for GNSS systems to work?
What do the segments do?
Answer: Three Segments:
Space Segment:
- min of 24 satellites on 6 different orbits
- On any point in on Earth at least 4 satellites are visible
Control Segment
User Segment
,◉ How does satellite Navigation Work?
Answer: -Transliteration: Distance
- Speed of light used to calculate distances
- Ranging measurements are based on timing
- times in the transmitters and the receiver have to be coordinated
◉ Calculation location
Answer: -Received signals allow the calculations of distance
between satellites and the receiver and also calculate the position
- The more signals received the more accurate the position
◉ In terms of Satellites what is the almanac and the ephemeris
Answer: Almanac: Contains less accurate orbital info than
Ephemerides and is valid for 90 days. Can speed up the time to the
receiver takes to find the first few satellites. System wide.
Ephemerides: Detailed info on the day and time, Satellite accuracy,
health, and age of data. This information is only valid for 2 hours
** A receiver can work without Almanac Data but always
ephemerides data
,◉ How is position determined ~
Answer: 1.Download almanac (information on satellites, their status,
health etc.)
2.Download ephemeris (predicted location of each satellite) and
synchronize receiver clock
3.Measure ∆T to at least 4 satellites
- Pseudorange = distance + effect of clock errors
- Error of 1 microseconds ~ 300 m, 1 nanoseconds ~ 30 cm
4.Determine range
5.Calculate X, Y, Z
◉ How is accuracy obstructed
Answer: - Number and position of Satellites
- Atmospheric effects
- Obstructions ( trees, buildings)
- Receiver quality
- Corrections/ Post processing
, ◉ What is differential GNSS
Answer: - Method to increase accuracy
- Requires additional; receiver in known position as a reference
position
- Can increase accuracy from 10m to 10 cms
◉ What does PDOP stand for
Answer: Position Dilution of Precision
Higher PDOP = Lower Accuracy
Measurement accuracy depends on the satellite configuration
◉ What is A-GPS
Answer: A-GPS = Assisted GPS
- Improves performance and speed of a GNSS receiver by using the
cellular network towers that pass information about location and
relevant satellites to the receiver
◉ Where/when does GNSS not work?
Answer: Inside tunnels, buildings, and dense forests
Between tall buildings
Underwater and underground
COMPLETE QUESTIONS AND SOLUTIONS
GRADED A+
◉ History of GPS
Answer: -Developed by military in 1973
- Operational in 1995 24 -Satellites
- Many people started using it in 1996 Civilian asset in 2000
◉ How many segements are needed for GNSS systems to work?
What do the segments do?
Answer: Three Segments:
Space Segment:
- min of 24 satellites on 6 different orbits
- On any point in on Earth at least 4 satellites are visible
Control Segment
User Segment
,◉ How does satellite Navigation Work?
Answer: -Transliteration: Distance
- Speed of light used to calculate distances
- Ranging measurements are based on timing
- times in the transmitters and the receiver have to be coordinated
◉ Calculation location
Answer: -Received signals allow the calculations of distance
between satellites and the receiver and also calculate the position
- The more signals received the more accurate the position
◉ In terms of Satellites what is the almanac and the ephemeris
Answer: Almanac: Contains less accurate orbital info than
Ephemerides and is valid for 90 days. Can speed up the time to the
receiver takes to find the first few satellites. System wide.
Ephemerides: Detailed info on the day and time, Satellite accuracy,
health, and age of data. This information is only valid for 2 hours
** A receiver can work without Almanac Data but always
ephemerides data
,◉ How is position determined ~
Answer: 1.Download almanac (information on satellites, their status,
health etc.)
2.Download ephemeris (predicted location of each satellite) and
synchronize receiver clock
3.Measure ∆T to at least 4 satellites
- Pseudorange = distance + effect of clock errors
- Error of 1 microseconds ~ 300 m, 1 nanoseconds ~ 30 cm
4.Determine range
5.Calculate X, Y, Z
◉ How is accuracy obstructed
Answer: - Number and position of Satellites
- Atmospheric effects
- Obstructions ( trees, buildings)
- Receiver quality
- Corrections/ Post processing
, ◉ What is differential GNSS
Answer: - Method to increase accuracy
- Requires additional; receiver in known position as a reference
position
- Can increase accuracy from 10m to 10 cms
◉ What does PDOP stand for
Answer: Position Dilution of Precision
Higher PDOP = Lower Accuracy
Measurement accuracy depends on the satellite configuration
◉ What is A-GPS
Answer: A-GPS = Assisted GPS
- Improves performance and speed of a GNSS receiver by using the
cellular network towers that pass information about location and
relevant satellites to the receiver
◉ Where/when does GNSS not work?
Answer: Inside tunnels, buildings, and dense forests
Between tall buildings
Underwater and underground
