What is the purpose of a phase-locked loop in radio systems?

The purpose of a phase-locked loop (PLL) in radio systems is to synchronize the phase of an output signal with a reference signal. A PLL operates by continuously adjusting the output signal to match the frequency and phase of the reference signal. This is crucial in radio communications because it allows for precise frequency control and enables systems to lock onto and track incoming signals. Essentially, the PLL ensures that the output remains in sync with the incoming reference, which is vital for maintaining the integrity and fidelity of the signal.

This synchronization capability is leveraged in various applications, including frequency synthesis, demodulation, and signal recovery, making PLLs fundamental components in modern communication systems. Other options, while related to signal processing and communication, do not accurately describe the core function of a phase-locked loop. Maintaining signal strength, filtering noise, or converting signals do not capture the primary role of a PLL in synchronizing frequencies and phases.