Checking process for security documents such as banknotes

摘要

A checking system for, e.g. banknotes has a strip sensing unit (8,9) that is capacitively coupled to a high frequency transmitter (12) and a high frequency receiver (13) that is coupled to a selective amplifier (14). This connects with an integrator (15) and a trigger (16). The trigger is used to activate an optical sensor (20) and also provides a timing pulse for a mono-stable device generating an output signal. The signals are received by a processing unit that identifies the specific form of the signal relating to a banknote.