1. The locating of a signal within a given frequency range. In a phase-lock loop, for example, acquisition is the process by which the loop searches for the reference signal, which is then employed to stabilize the frequency of a different frequency oscillator.

2. The locating of a signal in space. In radar systems, for example, acquisition is the process of sweeping a receiving antenna in the azimuth and elevation directions searching for a signal from a target.