CipherLinx® also offers advantages in physical security. If an attacker gains access to an authorized transmitter, then the system is compromised no matter how secure the transmission is. This is addressed by allowing the user to set a four-digit PIN that must be entered before the encoder activates. Another advantage is the multiple site setup. Once a decoder is set with a list of learned users and their permissions, it can be copied to another decoder. This prevents having to completely set up multiple locations such as a front door, back door and side door. The copies lose most of their abilities, so they cannot be altered from the original decoder’s state. Transmitter and receiver control lines offer control outputs to help eliminate additional external circuitry and facilitate power saving for external devices. The encoder activates the transmitter only when data is being sent. The decoder cycles power to the receiver at a low duty cycle, resulting in 90% power savings. The cycle time is quick enough to reliably receive transmitted data and the control output stays on until there is no data.