Technical Manual

Technical Manual
ARGUS AM Floor System
AM operating principle v1.2 Page 11 of 65
6 AM operating principle
The NEXUS AM operates on the pulse-listening principle. Using the zero crossing of the
50 Hz (or 60 Hz) mains frequency as a trigger, a short burst of 58kHz signal is transmitted
and a receiver window is ‘opened’ after the transmission burst has stopped.
If a tag was present within detection range during the transmission burst, the resonance of
this tag will be detected in the receiver window and an alarm will be triggered.
A single 50 Hz (or 60 Hz) mains frequency cycle is dived into three phases; phase A, B
and C. Each phase covers 1/3 of the 50 Hz cycle duration.
Figure 1 shows the AM operating principle (at 50Hz, with a default delay of 200μs) during
one 50Hz cycle.
Figure 1: AM operating principle
Transmission burst
Receiver window
Phase C
Phase B
Phase A