No they’re not. We can define ‘proximity token’ as an RF device used for identification. Here’s a quick summary of the main types used in access control:
Passive
A passive proximity token does not contain a battery. The token is given the energy to transmit its number by being placed near the reader. An electrical current is induced by placing the token’s inductance coil within the electromagnetic field of the reader.
There are varying types of passive tokens ranging from low cost Electromarin tokens through to higher security solutions such as Hitag2. These higher security tokens require matching security passwords at both reader and token meaning that they are much more difficult to reproduce.
Active
Active tokens (you may have guessed what I’m about to say) contain a battery. As they have their own power source these tokens can often be read while much further away from the proximity reader. This can facilitate hands-free operation and can be useful when using a proximity token to open a barrier to a car park, for example.
Obviously batteries will need to be changed eventually and active tokens are usually larger and more expensive to purchase.
High frequency
‘Normal’ proximity readers operate at around 125KHz. ‘High frequency’ generally refers to readers and tokens working from 13.5MHz right up to 2.4GHz (microwaves).
This higher frequency offers a couple of significant benefits. One of which is that the rate of data transfer is much higher. This difference is imperceptible when transmitting a simple identification number but can be an advantage when handling the more complex data exchanges common with smartcard applications. In addition, high frequency tokens can have a simpler construction as they can operate with a very simple inductance coil. This simple inductance coil can be printed onto a PCB, or even paper, reducing the cost and opening up markets such as baggage tracking.
Predictably, there are drawbacks. The higher frequency means a shorter wavelength which is more susceptible to interference and doesn’t have the reach of lower frequencies. Just like short-wave, medium-wave and long-wave on your radio in fact.
