I knew the basics but stumbled when they pushed on the clock accuracy piece.
Start with a high-level overview of GPS as a trilateration system, then dive into the technical details of signal timing, clock synchronization, and error sources. Use a structured narrative that connects satellites, receiver, and computations, and relate it to software engineering concepts like distributed systems and error handling.
Pro tip: Emphasize the elegance of using relativity corrections and statistical filtering (e.g., Kalman filters) to handle errors, showing you understand real-world system design beyond textbook theory.
Explain that GPS uses a constellation of satellites broadcasting signals, and a receiver trilaterates its position by measuring distances to at least four satellites.
Describe how the receiver measures the time it takes for a signal to travel from satellite to receiver, then multiplies by the speed of light to get the distance (pseudorange).
Discuss why atomic clocks on satellites and quartz clocks in receivers must be synchronized, and how the receiver solves for its clock bias using a fourth satellite.
Explain how distances from multiple satellites are used to solve for the receiver's 3D position (latitude, longitude, altitude) and time offset via equations.
Identify common errors (ionospheric delays, multipath, satellite clock errors) and mention techniques like differential GPS, Kalman filtering, and augmentation systems to improve accuracy.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.