What mechanism does a radio use to prevent unauthorized access?

A radio uses encryption and control features as its primary mechanism to prevent unauthorized access. This process involves encoding the information transmitted over the airwaves, ensuring that only properly equipped and authorized devices can decode and understand the messages being sent. Encryption not only secures communications against eavesdropping but also assists in authenticating the source of the transmitted information, thus preventing interception or misuse by unauthorized parties.

Control features complement encryption by allowing operators to set specific parameters regarding who can access the device and under what conditions. These could include user authentication protocols, access control lists, and other settings that restrict usage based on predefined criteria, further enhancing security measures in place to protect against unauthorized access.

Physical locks on the transmitter may provide a basic level of security by preventing physical tampering, but they do not address the issue of encrypted communications. Similarly, manual tuning restrictions and limited broadcasting range help manage operational use but do not directly prevent unauthorized access. They are more focused on operational effectiveness rather than security. Thus, encryption and control features are the most effective means of securing radio communications against unauthorized access.