A GNSS integrity monitoring station with Software Defined Radio and low cost receivers

This article describes a GNSS monitoring station over the L band. The monitoring is performed in two different ways: over the signal's spectrum by means of statistical analysis and in the range domain determining the horizontal protection level. The horizontal protection level ensures that the user's location is within a certain range with a certain probability and is used as input in decision making process. If the system detects an anomaly in the GNSS spectrum and the protection level exceeds a certain threshold an alarm is sent to the control center. If available, the station uses satellite based augmentation to obtain differential corrections and integrity data. The monitoring station uses low-cost GNSS receivers, software radio techniques and operates in real time sending alarms in seconds.