In our previous article, we have already explained the difference between NFC, BLE and RFID systems. But now we want to go into a little more detail about the latter. How does RFID actually work and what functions do transponders need to work? This article answers these questions.
What is a transponder?
If you are interested in aircraft guidance, chances are you have come across this word. But in fact - like many things - it's not just used by one industry. A transponder is a transceiver that, when it receives a suitable signal, sends back its own in response. It's used beyond air traffic control on satellites, in the automotive industry (transponders are used to ensure that a car will only start with a key paired to it) and, of course, in the world of access control systems.
What is RFID?
It is a radio frequency identification technology. It is used, for example, for bank cards. When the card is touched near a terminal, it is charged with some electricity and emits a signal that allows the reader to identify the card and start, for example, a payment. Or in the case of an access control system, the door opens.
RFID transponders are therefore access cards themselves!
RFID uses transponders, often called tags, but which can also take the form of cards. We usually refer to them as identifiers. Transponders always have a specific, unique identification number, which is stored in the memory of the chip. So-called ‘smart card’ identifiers have additional memory that can store much more data than just the identification number. This memory capacity is often used in payment applications, time- or location-specific access authentication or other applications that require high security or significant data storage.
The memory of smart cards can also support high-security encryption protocols during identification transactions - where the unique identification number of the transponder is not secure enough.
They are no longer just readable, they can even be written!
Some RFID readers have the additional capability to write data to transponders during transactions. Writing new data to transponders is a common occurrence in payment, token or similar applications, for example where transponders store a limited number of authorised transactions. Each read transaction reduces the number available in the transponder, which is then overwritten by the reader.
Active or passive transponder?
Active transponders are self-powered, while passive transponders only work when a reader induces them to wake up and retrieve the data on them. Passive transponders therefore only work if they are brought close enough to a reader that can read them.
There are several types of RFID transponders
There are several types of transponders depending on the installation. RFID transponders can look very different depending on the environment and the purpose for which they are intended. An RFID transponder can be a keychain, a wristband or card that looks like a watch, and many more, depending on the installation and the purpose. Tags attached to different objects are often stickers or buttons. A common feature of all transponders is that each contains an RFID chip that is read by the reader.
Depending on the material, the transponders can withstand different, even harsh conditions. In general, RFID transponders, especially those specifically designed for industrial environments, are highly resistant to chemicals, heat, water, dirt and shock. For example, RFID tags are successfully used to mark clothes that require regular laundry processing.
For metal surfaces, special dedicated transponders are available. Special transponders are also needed for windscreens. Transponders (identifiers) intended for metal surfaces and windscreens may not work well on other surfaces, so it is important to choose the right identifier for each purpose. The further away the reader has to read the transponder, the more important it is to optimise the placement of the reader and the identifier during installation.
Learn about the different identification technologies and access options. Contact us, our experts and sales staff are ready to help you.
