Test of pseudorange accuracy in GNSS RF constellation simulator

One of the most important performance parameters of a GNSS RF (radio frequency) constellation simulator is the pseudorange accuracy. Assuming that mathematical model of the simulator can calculate the pseudorange correctly, the SV (satellite vehicle) code phase error in the generated RF signal still exists due to digitization-induced error and analog distortion in the non-ideal signal generation chain of the RF signal simulator and inaccurately represented navigation message. So far no standard definitions and test methods can be found on Simulator specifications. This paper explores a closedloop test method based on a high performance software GNSS receiver. The methodology description is focused on receiver measurement error analysis in strong signal condition with prior knowledge aiding and specialized test receiver design. A single-SV timing and ranging algorithm is presented to solve the time alignment and pseudorange ambiguity problems. The methods are validated through extensive closed-loop test at both digital IF (intermediate frequency) signal level and RF signal level using GNSS RF constellation simulators from four manufacturers.