Back in 1945, Leon Theremin discovered an espionage tool designed for the Soviet Union. The unit retransmitted instant radio waves using audio information. The sound waves vibrated on the diaphragm which changed the shape of the resonator that regulated the replicated radio frequency. Although the pioneer device was a merely listening gadget, it is held as the predecessor of the RFID technology.
The RFID is composed of dual-way radio transmitter-receivers known as readers or interrogators that transmit signals from the tag and also receive the response. The user of the acquired information typically sends it to a PC that is running RFID software.
The information received from the tags stored in electronically in a non-flexible memory. This RFID is often stored in inflexible memory. The tag readers send programmed radio signals to interrogate the tag. After the tag reads the message, it responds with identification information. This can be a distinct tag serial number or just product-related information like the stock number, production date, batch or lot number, or other specified information.
RFIDs are often active, passive or battery assisted. The active tag varieties come with onboard batteries and occasionally transfer their ID code. The battery assisted passive (BAP) comes with small batteries onboard that are activated when in proximity to an RFID reader. The passive tags are smaller and more affordable because they have no battery. Instead, it uses the radio energy passed by the reader as its power source. The interrogator requires being close in order for adequate power to be generated. To differentiate the different tags in the proximity of a RFID system, each of them is allocated a unique code. This implies that it is possible for the system to read several units at the same time without confusing them.