Which statement best describes GNSS pseudorange measurement and its relation to the receiver clock error?

• A. The geometric distance from the receiver to the satellite, ignoring clock errors.
• B. The measured distance to a satellite including the receiver clock bias; it's used to solve for position and clock error.
• C. The satellite's own clock bias is included in pseudorange measurement.
• D. Pseudorange is the distance from the satellite to the GNSS constellation center.

Answer: (B)

Pseudorange is the observed range to a satellite that includes the receiver’s own clock error. When the receiver measures the time difference between its local clock and the satellite’s transmission, converting that time to distance with the speed of light adds a term for the receiver’s clock bias. So the pseudorange value equals the true geometric range plus c times the receiver clock bias (along with small additional biases from other errors). Because you have multiple satellites, you can solve a set of such equations to determine the receiver’s three position coordinates and the receiver’s clock error. This is why describing pseudorange as the measured distance including the receiver clock bias—and using it to solve for position and clock error—is the correct interpretation. The satellite clock bias enters the model too, but the key point is that the receiver’s uncalibrated clock is the unknown you solve for with these measurements; the other options either ignore the clock error, misstate whose clock bias is involved, or describe an irrelevant concept.