Which system is employed to enhance the range of hand-held portable radios?

The repeater system is designed to enhance the range of hand-held portable radios by receiving a radio signal and then retransmitting it at a higher power or from a better location. This process helps extend the communication range for users who may be at a distance from each other or in areas with physical obstacles that can weaken or block radio signals. By effectively amplifying the signal, repeaters allow for clearer and more reliable communication over greater distances, making them crucial in emergency services where maintaining contact is vital.

In contrast, other systems like talk-around, simplex, and duplex serve different functions. A talk-around system allows users to communicate directly without using a repeater, which can limit range. The simplex system is a one-way communication method, facilitating a single transmission channel in one direction at a time. The duplex system allows for simultaneous two-way communication but does not inherently extend range. Therefore, the repeater system stands out as the most effective method for enhancing communication range in hand-held portable radios.