The Federal Aviation Administration (FAA) Wide Area Augmentation System (WAAS) Monitoring Team has investigated increases in Radio Frequency Interference (RFI) events observed since 2009. The Oklahoma City-based WAAS Monitoring Team initially observed in-creased RFI events at certain WAAS Reference Stations (WRSs). The major source for this increase in RFI events has been attributed to Global Positioning System (GPS) maskers used in motor vehicles for personal privacy. The use of these Personal Privacy Devices (PPDs) is observed in WRS operation via a response in the Automatic Gain Control (AGC) and the signal to noise ratio (C/N0) report-ed by the reference receivers.