Fundamentals of GIS Exam 2 Questions with Complete Solutions (Latest 2025) GNSS - Correct Answers ✅Satellite-based technologies that give precise positional information -Day or night -Most weather and terrain conditions -Inexpensive, accurate, and easy to use.-Most common method of field data collection for use in GIS.GNSS Terminology - Correct Answers ✅-The generic acronym is GNSS.-The acronym GPS actually applies to the U.S. NAVSTAR system.-GPS is widely used as a generic acronym, in a similar fashion as...Jacuzzi : hot tubs :: GPS: GNSS NAVSTAR (aka GPS) - Correct Answers ✅-First deployed -Most widely used system -Military/civilians applications -Designed to operate with 24 satellites.
-Satellites in orbit: 31
-First launch: 1978
-Total launches: 72
-Orbital height: 20,180 km (12,540 mi) 1 / 3
Fundamentals of GIS Exam 2 Questions with Complete Solutions (Latest 2025) Components of GNSS - Correct Answers ✅1. Satellite Segment -Constellation of satellites orbiting and transmitting signals (21+ satellites, 6 orbital planes, 12 hr return interval for each satellite) -4 to 8 usually visible
- Control Segment
- User Segment
-Tracking, communications, data gathering, integration, analysis, and control facilities.-Five stations for the GPS system -Master Control Station (Colorado) -The satellites have to be maintained!
-GNSS receivers - any device that records data transmitted by each satellite and then processes these data to obtain 3D coordinates -Manufacturers have developed receivers capable of receiving both GPS and GLONASS.-Receivers specializing in GIServices vs. specialized GIS data collection receivers GNSS Positioning - Correct Answers ✅GNSS positioning is based on radio signals broadcast by each satellite.
-Receivers decode each signal to identify: Satellite,
Transmission time, Satellite position 2 / 3
Fundamentals of GIS Exam 2 Questions with Complete Solutions (Latest 2025) -This in combination with signals from other satellites is what is needed for positioning.Range Distance Measurements - Correct Answers ✅Range
- distance between two objects
-E.g. distance between satellite and receiver
-Range distance: range = speed of light * travel time, where
travel time is (t1 - t0) -Simultaneous range measurements from multiple satellites are used to estimate a receiver's location.How does your smartphone know your location? - Correct
Answers ✅https://youtu.be/70cDSUI4XKE
Positional Uncertainty - Correct Answers ✅-Uncertainty in range measurements leads to position errors in GNSS measurements.-Measured travel time errors (timing errors) are often the largest sources of positional uncertainty.Positional dilution of Precision (PDOP) - Correct Answers ✅- High PDOP = satellites close together, less accurate -Low PDOP = satellites wide apart, smaller area of uncertainty
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