Plain English Meaning

A pseudorange is the GPS receiver's best guess of how far away a satellite is, based on how long the signal took to arrive. It is only a guess at first because the receiver's clock is not perfectly accurate, so the distance it calculates is slightly off until the receiver compares signals from several satellites and corrects itself.

Full Definition

A pseudorange is the GPS receiver's calculated distance to a satellite, derived from the time it takes a signal to travel from the satellite to the receiver. It is called 'pseudo' because the measurement contains a timing error caused by the receiver's inexpensive clock not being perfectly synchronized with the satellite's atomic clock. The receiver resolves this error by comparing pseudoranges from at least four satellites simultaneously.

Context Anchor

Seen in GPS discussions about how a receiver calculates position from satellite signals.

Derivation

From 'pseudo' (Greek pseudes, meaning false or apparent) plus 'range' (distance). It is a 'false range' because the measured distance contains a known error that must be corrected before the position is trustworthy.