A device for the detection or demodulation of a frequency-modulated (FM) wave. Frequency-modulation detectors operate in several ways. In one class of detector, known as a discriminator, the frequency modulation is first converted to amplitude modulation, which is then detected by an amplitude-modulation detector. Another type of FM detector employs a phased-locked oscillator to recover the modulation. A still different type converts the frequency modulation to pulse-rate modulation, which can be converted to the desired signal by use of an integrating circuit. Examples of these types will be discussed here.