GPS Workshop Quiz
Test your knowledge from the workshop! Click on an answer to see if you're correct.
GNSS (Global Navigation Satellite System) is the umbrella term that encompasses all satellite-based navigation systems. GPS is specifically the United States' system, while GNSS includes GPS, GLONASS (Russia), Galileo (EU), and BeiDou (China).
The correct answer is B) GNSS. GNSS (Global Navigation Satellite System) is the umbrella term that encompasses ALL satellite navigation systems. GPS is only the US system.
4 satellites are needed for a 3D fix. Three satellites give you X, Y, Z coordinates, but a fourth is required to solve for the receiver's clock error (since consumer GPS receivers don't have atomic clocks like satellites do).
The correct answer is C) 4 satellites. While 3 satellites could theoretically give 3D position, the 4th satellite is essential to correct for receiver clock errors.
Trilateration uses only distance measurements to find a position. Unlike triangulation (which uses angles), trilateration determines position by finding where multiple spheres of known distances intersect.
The correct answer is B) Trilateration. Many people confuse this with triangulation, but GPS uses distances (not angles) to calculate position.
Dilution of Precision (DOP) describes how the geometric configuration of satellites affects position accuracy. When satellites are spread across the sky, DOP is low (good). When clustered together, DOP is high (poor accuracy).
The correct answer is B) Dilution of Precision. DOP measures how satellite geometry affects the accuracy of your position fix.
GPS satellite signals cannot pass through solid materials like rock, concrete, metal roofs, or water. The signals travel at the speed of light but are absorbed or blocked by dense materials, making indoor positioning impossible with GPS alone.
The correct answer is A) GPS signals are blocked by solid materials and water. GPS signals can't penetrate rock, concrete, metal, or water - they need a clear line of sight to satellites.
GPS satellites orbit at approximately 20,200 km in Medium Earth Orbit (MEO). This is much higher than the ISS (400 km) but lower than geostationary satellites (36,000 km). At this altitude, each satellite completes 2 orbits per day.
The correct answer is C) 20,200 km. GPS satellites are in Medium Earth Orbit, completing two full orbits around Earth every day.
The L1 signal (1575.42 MHz) is the primary civilian GPS frequency. It carries the C/A (Coarse Acquisition) code that most phones and consumer GPS devices use. L2 and L5 are used by more advanced receivers for improved accuracy.
The correct answer is A) L1 (1575.42 MHz). This is the main civilian frequency used by smartphones, car GPS, and basic receivers like our Arduino NEO-6M module.
All satellites are above the horizon from a ground receiver's perspective. This means the geometric intersection of satellite signals is better distributed horizontally than vertically. Vertical accuracy is typically 1.5 to 2 times worse than horizontal accuracy.
The correct answer is B) All visible satellites are above the horizon. Since no satellites are below you, the vertical geometry (VDOP) is always worse than horizontal geometry (HDOP).
Consumer-grade GPS (smartphones, handheld units, Arduino modules like our NEO-6M) typically achieves 3-15 meter accuracy. Survey-grade equipment using RTK can achieve centimeter accuracy, but requires expensive dual-frequency receivers.
The correct answer is C) About 3-15 meters. Consumer GPS devices, including our Arduino builds, typically have 3-15 meter accuracy in good conditions.
Eratosthenes noticed that on the summer solstice, the sun cast no shadow in Syene (Aswan) but cast a 7.2° shadow in Alexandria. He knew the distance between the cities (~800 km) and calculated: if 7.2° = 800 km, then 360° = ~40,000 km. This is remarkably close to Earth's actual circumference!
The correct answer is B) He measured shadow angles at two cities. Using the difference in sun angle between Alexandria and Syene, combined with the known distance between them, he calculated Earth's circumference within a few percent of the actual value!