GPS signal structure — what do satellites transmit and how is range measured? Which consolidated statement about GPS L-band signals, satellite PRN codes, and receiver ranging is correct?

Introduction / Context:
Understanding how GPS measures distance helps explain both its strengths and its error sources. Satellites broadcast coded L-band signals that receivers decode to separate satellites and to determine the apparent signal travel time, which is then converted into pseudorange.

Given Data / Assumptions:

• Classical GPS description (L1, L2; modern systems add L5 and new codes).
• Receivers correlate PRN codes to estimate delay.
• Distance is derived from signal travel time multiplied by the speed of light, corrected within the navigation solution.

Concept / Approach:

Each satellite has unique PRN codes modulating the L-band carrier(s). Code correlation in the receiver determines the code phase offset, which corresponds to the signal transit time (plus biases). Multiplying by the speed of light yields a pseudorange; with multiple satellites, the receiver solves for position and clock bias.

Step-by-Step Solution:

Verification / Alternative check:

Any GPS fundamentals text shows L1/L2 with PRN coding and the correlation process for ranging. Modernized signals (e.g., L5) extend but do not change the basic principle.

Why Other Options Are Wrong:

• Options (a)–(d) are individually correct; hence the combined correct choice is “All of these”.

Common Pitfalls:

• Confusing carrier phase tracking (much more precise) with code-phase ranging.
• Forgetting that ranges are “pseudo” because of clock and media delays.

Final Answer:

All of these.