The report evaluates possible interference detection methods based on available data from three commonly used receivers in the Swedish CORS network Swepos, which is the support system for satellite based positioning used in Sweden. Detection based on commonly available data such as signal strength (C/N0) or more specific data like receiver specific detectors, as well as low level data from receivers such as AGC (automatic gain control) gain is investigated. Detection performance is also compared with that achieved by the detection system RF Oculus that has been developed by FOI. The measurements has shown that its possible to detect interference/jamming, and also spoofing with the use of avalible data from the receivers. The detection performance achieved is proven to be similar to performance of the RF Oculus detectionsystem, but further studies are needed to be able to set the threesholds for detection to minimize the risk for false detections.