A device that combines an electrical information signal with a periodic electrical carrier signal for efficient transmission. The modification of a usually sinusoidal electrical carrier signal (or simply carrier) for the purpose of transmitting information which is carried on a second electrical modulating signal or information signal is called modulation. The device or circuit that performs the modulation is called a modulator. The information may be from any of a variety of sources such as sensor data, speech signals, or image data. The modulator varies the carrier in amplitude, frequency, phase, or some combination in order to imbed the information for efficient transmission. During the process of modulation, information is shifted in frequency from baseband to the carrier frequency for efficient transmission.