A system is provided that has an ECM (electronic counter measures) system and a transponder monitor connected to or forming part of the ECM system. The system monitors for a transponder signal from a remote transponder. The system determines information, such as transponder location, based on the transponder signal and makes use of the information in the ECM system and/or the system extracts encoded information contained in the transponder signal, such as information about a transponder owner, such as status of consumables, medical status. The ECM system may have a reactive jammer that is used both for a reactive jamming function, and as the transponder monitor function.