What does DGPS rely on to determine the error in the signal?

What does DGPS rely on to determine the error in the signal?

• A. A second receiver at a known fixed location compared to satellite calculations
• B. A single receiver using satellite data only
• C. An additional ground station that broadcasts ionospheric corrections
• D. A post-processing method applied after data collection

Answer: (A)

DGPS works by using a fixed reference receiver at a known location to measure the discrepancy between what the satellites are computed to tell us and what those satellites are actually delivering to that known point. That difference represents the errors affecting the GPS signals (such as satellite clock errors, atmospheric delays, and receiver biases). The base station then broadcasts these corrections to nearby rovers, which apply them to their own measurements, yielding more accurate position fixes. This is why a second receiver at a known location is essential—the reference point lets you quantify the error in real time. A single receiver cannot determine that error on its own. Using an additional ground station to broadcast ionospheric corrections describes a broader augmentation approach (like WAAS) rather than the classic DGPS method. And while corrections can be applied in post-processing, DGPS is specifically about real-time corrections derived from the fixed reference station.

DGPS works by using a fixed reference receiver at a known location to measure the discrepancy between what the satellites are computed to tell us and what those satellites are actually delivering to that known point. That difference represents the errors affecting the GPS signals (such as satellite clock errors, atmospheric delays, and receiver biases). The base station then broadcasts these corrections to nearby rovers, which apply them to their own measurements, yielding more accurate position fixes.

This is why a second receiver at a known location is essential—the reference point lets you quantify the error in real time. A single receiver cannot determine that error on its own. Using an additional ground station to broadcast ionospheric corrections describes a broader augmentation approach (like WAAS) rather than the classic DGPS method. And while corrections can be applied in post-processing, DGPS is specifically about real-time corrections derived from the fixed reference station.