The System
Module 3: Personnel Safety Module
The transponder, also known as a PSM, consists of the antenna coil and a chip.
A chip is an electronic circuit that can take on many different functions. It can be both a receiver, i.e. it must know that it is in a protective electronic field, and a transmitter, in that it returns the response signal. Like all electronic circuits the chip needs electrical current to operate. There are basically two types of transponder:
a) Passive transponders which draw their operational current from the interrogation field. Most transponders in current use are passive, such as those used in inventory tracking and access systems. These transponders usually have a range of less than 50 cm. They can only be used in safety applications in an extremely limited capacity or not at all.
b) Active transponders which have their own (lithium) battery. These can cover great distances and at the same time also meet the system requirements mentioned above. U-Tech supplies active transponders in either wristwatch or pocket format half the size of a cigarette packet.
