What is the purpose of a radio repeater?

A radio repeater functions primarily to extend the range of radio communications. It achieves this by receiving a radio signal and then retransmitting it, effectively amplifying the signal and allowing it to cover greater distances or overcome obstacles that might impede direct transmission. This is particularly significant in situations where the original signal would be too weak to be received over long distances due to terrain, distance, or other factors.

While improving audio quality or converting signal types can be beneficial aspects of radio communication systems, they do not capture the fundamental purpose of a repeater. Additionally, encryption relates to securing communications rather than enhancing range, which further clarifies the repeater's specific role in radio systems. Thus, the correct answer accurately identifies the primary function of radio repeaters within communication networks.