Global Positioning System (GPS) residual error sources: identify which categories of biases affect positional accuracy after basic corrections.

Introduction / Context:
GPS accuracy is influenced by several residual biases even after applying standard models and corrections. Understanding the taxonomy of errors helps in selecting techniques such as differential GPS (DGPS), real-time kinematic (RTK), or precise point positioning (PPP) to mitigate them.

Given Data / Assumptions:

• Satellite-dependent errors: ephemeris/orbit and satellite clock uncertainties.
• Receiver-dependent errors: receiver clock stability, multipath susceptibility, hardware delays.
• Propagation errors: ionospheric and tropospheric delay variability along the path.

Concept / Approach:
Residual biases can be partitioned by origin: space segment, user equipment, and the propagation medium. Combining dual-frequency measurements, reference-station corrections, and robust hardware mitigates but does not completely remove these effects.

Step-by-Step Solution:
Identify satellite-dependent terms: orbit/clock errors affect all receivers similarly at a given epoch.Identify receiver-dependent terms: internal clocks and multipath vary user-to-user.Identify propagation terms: ionospheric TEC variations and tropospheric water vapour cause range delays.Since all categories are real contributors, the inclusive option is correct.

Verification / Alternative check:
Surveying textbooks and GNSS standards list these three classes as principal residuals.

Why Other Options Are Wrong:

• Selecting only one category understates the multifactor nature of GPS error budgets.

Common Pitfalls:

• Conflating multipath (receiver environment) with ionospheric delay (propagation).
• Ignoring ephemeris updates cadence and precision orbit products.

Final Answer:
All the above