Access Control Systems - How It Works
How Proximity System works.
The Key elements of the system are The Tag, The Reader, The Controller and The Lock.
The Tag – Each user has a Tag which will be authorised on certain doors at specific times by the system administrator,
The Reader – Is on the controlled side of the door (both sides if control is in and out). The Tag is presented in the proximity of the reader and, if authorised at that time on that door, the door lock will be opened.
The Controller – This is the core of the system, it stores all the authorisation information, which it receives from a PC. When it receives a Tag ID from a reader, it release a door lock if that Tag is authorised at that door.
The Lock – This can be any electro-mechanical locking device, fail safe or fail secure.
The access control system is an electronic system which utilises electronic keys (the tags) to release door locks. The tag, which can be carried by the user on their key ring, is presented in the Proximity of a reader, located adjacent to a door and communicates with that reader utilising encoded radio waves.
There is no need for any contact between the Tag and the Reader. Once a tag is recognised by the reader, if it is authorised on that door, a signal is transmitted to release an electrically managed the door lock.
Each tag has a unique number stored on an electronic chip encased in plastic. There is no power source (battery) within the tag.
The reader is basically an antenna which is hard wired to a control unit.
The reader on the door is powered, via the control unit. It emits radio waves via its antenna.
The tag also has an antenna which receives the radio waves from the reader. When the tag is within approximately 75mm of the transmitter, the power contained within the transmitted radio waves is sufficient to induce a small current in the chip contained in the tag. This current powers and operates the chip which is “programmed” to send an encrypted unique ID number back to the reader.
The reader sends this unique number back to the controller, which contains a digital decoder, memory and an IC (integrated circuit). The IC controls the operation and “decides” what to do with any information that the reader sends to it.
Via the decoder the unique identification number is extracted from the signal that the tag sent.
The controller compares the ID number against stored tag numbers that the administrator has already loaded to the unit. If the number received has been stored in the unit, and has been authorised to have access to that door at that time, the IC is programmed to send an electrical signal to unlock the lock. The duration of this signal is programmed by the administrator.
The signal sent by the control unit operates the electrical door lock which releases a physical stop on a door lock allowing it to be opened by the tag owner.
Instead of using a Tag, biometric information can be used, this is sent from the biometric reader to the controller in the same way as the Tag ID. This can be fingerprint, hand print, iris recognition or face recognition.
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