By far the most used access control solution is the Radio Key Fob. This is a small hand held device which sends a coded radio signal on either a 433mHz frequency or an 868mHz frequency. A Radio receiver (often referred to as the RX) deciphers the signal and activates the gate. There are 3 main types of Radio transmitters. Each type has distinct advantages and dis advantages.
- Quarts 40.6mHz transmitters are no longer available as the 40.6mHz frequency has been reserved for use by the emergency accross Europe. If you have a Quarts system you will need to add a new stand alone receiver to the gate system before adding new transmitters that will work along side the existing ones.
- Dipswitch or Copy transmitters are very common in the industry. They typically come in 433 or 868 mHz versions and are preferred because they are so easy to work with. Copy transmitters are the newest version of this technology. They let the user to clone the signal sent by an existing transmitter, allowing a gate system to have many key fobs using 1 code. This means adding new transmitters is easy but if one has to be deleted off all the transmitters must be removed, the master code changed and then all the transmitters programmed or copied back on.
- Rolling code transmitters can also come in 433 and 868 mHz frequencies but are not compatible with the copy transmitters above. Instead of sending a simple code to the radio receiver they send part of a code which is used to solve a computation inside the receiver. Each time the button is pushed on a Rolling code transmitter the code snippet sent is change. This means that each Rolling code transmitter is unique and cannot be copied, making it perfect for higher security applications. It is also the best transmitter platform to use for large or complex site which require high levels of management as each transmitter can be edited individually more easily.
Here are some examples of different transmitters designs.