RNR 2102 Exam with Questions 100%
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Answers
What is GPS? Explain the basis of GPS and how it works. - ✔ANS GPS is a global navigational
satellite system created by DoD (Dept of Defense). It uses a constellation of 30 satellites (needs
4-7 for a reading), triangulates the users position, radio waves travel at speed of light. Relies
on accurate time keeping
What are measurement offsets? - ✔ANS Measure distance and direction from a
known location to an object of interest
What range should you ideally attempt to maintain PDOP within? - ✔ANS <=4
The process of first collecting GPS data in the field and later applying corrections to those
data is often termed ___. - ✔ANS post-processing
What is selective availability? - ✔ANS Before May 1, 2000, commercial GPS signals
were scrambled to limit precision to about 100 m
What is multipath error? - ✔ANS signals reflecting off obstructions before reaching
GPS (cannot be corrected)
, Why are survey-grade GPS more accurate than commercial-grade GPS? - ✔ANS It
receives both L1 and L2 signals, while commercial-grade GPS only receives L1 signals
Differential GPS
a. Relies on use of base stations in addition to the GPS receiver
b. The GPS data are adjusted in real time
c. Generally results in increased accuracy of geographic fixes
d. All of the above
e. None of the above - ✔ANS D
A ___ is a smooth, mathematical representation of the Earth's surface that best fits the
global mean sea level. - ✔ANS geoid
A ___ is a set of referenced points against which position measurements were made -
✔ANS geodetic datum
What are the main differences between NAD27 and NAD83? - ✔ANS NAD27
- Based on 25,000 locations
- Referenced to central location (Meades Ranch in Kansas)
NAD83
- Based on 270,000 locations
- Referenced to Earth's center
- Uses GRS80 ellipsoid
The difference between NAD 83 and WGS84 can be up to 10 meters. - ✔ANS F; up to 1m
Solved |Latest Update| Verified
Answers
What is GPS? Explain the basis of GPS and how it works. - ✔ANS GPS is a global navigational
satellite system created by DoD (Dept of Defense). It uses a constellation of 30 satellites (needs
4-7 for a reading), triangulates the users position, radio waves travel at speed of light. Relies
on accurate time keeping
What are measurement offsets? - ✔ANS Measure distance and direction from a
known location to an object of interest
What range should you ideally attempt to maintain PDOP within? - ✔ANS <=4
The process of first collecting GPS data in the field and later applying corrections to those
data is often termed ___. - ✔ANS post-processing
What is selective availability? - ✔ANS Before May 1, 2000, commercial GPS signals
were scrambled to limit precision to about 100 m
What is multipath error? - ✔ANS signals reflecting off obstructions before reaching
GPS (cannot be corrected)
, Why are survey-grade GPS more accurate than commercial-grade GPS? - ✔ANS It
receives both L1 and L2 signals, while commercial-grade GPS only receives L1 signals
Differential GPS
a. Relies on use of base stations in addition to the GPS receiver
b. The GPS data are adjusted in real time
c. Generally results in increased accuracy of geographic fixes
d. All of the above
e. None of the above - ✔ANS D
A ___ is a smooth, mathematical representation of the Earth's surface that best fits the
global mean sea level. - ✔ANS geoid
A ___ is a set of referenced points against which position measurements were made -
✔ANS geodetic datum
What are the main differences between NAD27 and NAD83? - ✔ANS NAD27
- Based on 25,000 locations
- Referenced to central location (Meades Ranch in Kansas)
NAD83
- Based on 270,000 locations
- Referenced to Earth's center
- Uses GRS80 ellipsoid
The difference between NAD 83 and WGS84 can be up to 10 meters. - ✔ANS F; up to 1m
