Patent ID: 6064296
Filing Date: 2000-05-16
Classification: G08B

Abstract:
An apparatus for the surveillance of an electronic security element in an interrogation zone, comprising:a transmitting device which emits at least one periodic interrogation signal into the interrogation zone, said interrogation signal causing the security element to deliver a characteristic signal;a receiving device for receiving said characteristic signal and generating a received signal (r(s)); anda computing/control unit which receives said received signal (r(s)) from said receiving device, evaluates said received signal (r(s)) and produces an alarm when the presence of a security element is established,said computing/control unit evaluates said received signal (r(s)) with respect to amplitude and phase (I component and Q component), determines, by approximation, an interference signal (fd(s)) occurring in said received signal (r(s)), and removes said interference signal (fd(s)) from said received signal (r(s)).