Abstract: An apparatus for an enhanced receiver for an RFID Tag Interrogator is described. The enhanced receiver has a zero crossing detector, a phase shifter, a pulse generator and a chopper. The zero crossing detector produces a sampling signal from the current transformer. The phase shifter modifies the sampling signal by producing a 90 degree phase shifted sampling signal. The pulse generator increases time duration of each pulse of the phase shifted sampling signal, which is then fed to the chopper. Thus, the chopper samples the backscattered carrier signal every 90 degree phase shift from the time when the backscattered carrier signal passes the zero crossing. This makes isolation of the backscattered signal from the carrier signal more effective.

Abstract: A security system for automatically transmitting alert signals when a security appliance such as a firearm (110) carried by a security officer is drawn from its holster (130), and the method of enabling such a function under the present invention is described. The present invention makes use of radio frequency identification tags (eg 120, 134) and readers (eg 136, 186) to trigger these automatic alerts. The present invention also uses s locator function associated with a mobile device to automatically direct aid to the officer in danger. The present invention also encompasses a method of conducting security guard patrols that monitors the progress of the security guard in real time as he logs each checkpoint of the tour, through the use of RFID tags and readers.