•However, the system errors (known as bias) in the clocks, and the refraction of the wave as it passes through the Earth’s atmosphere, must also be considered.
•Receiver clock bias can be mathematically determined by using the fourth satellite range, this solution allows the receiver to have a less accurate (and less expensive) clock.
•The system of equations used to solve for the position of the receiver and clock bias can be determined as code pseudorange model
11