A demodulator is an electronic circuit used to recover the information content from the carrier wave of a signal. The term is usually used in connection with radio receivers, but there are many kinds of demodulators used in many other systems. Another common one is in a modem, which is a contraction of the terms modulator/demodulator. Look up Electronic in Wiktionary, the free dictionary Electronic can refer to many things: Objects related to electronics The band Electronic. ... There are many kinds of circuit An electric circuit interconnects electrical elements. ... A carrier wave is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. ... The word receiver has a number of different meanings: In communications and information processing, a receiver is the recipient (observer) of a message (information), which is sent from a source (object). ... A modem (a portmanteau word constructed from modulator and demodulator) is a device that modulates an analog carrier signal (sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information. ... For the musical use of modulation, see modulation (music). ...

AM and FM demodulators

An AM signal encodes the information onto the carrier wave by varying its amplitude in direct sympathy with the analogue signal to be sent. There are two methods used to demodulate AM signals. Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. ... For the Analog Science Fiction and Science Fact publication, see Astounding Magazine. ...

The envelope detector is a very simple method of demodulation. It consists of anything that will pass current in one direction only, that is, a rectifier. This may be in the form of a single diode, or may be more complex. Many natural substances exhibit this rectification behaviour, which is why it was the earliest modulation and demodulation technique used in radio. The crystal set exploits the simplicity of the modulation to produce an AM receiver with very few parts. An envelope detector is a device which is used to demodulate AM signals. ... A rectifier is one or more diodes arranged for converting alternating current (AC) to direct current (DC). ... Types of diodes A diode functions as the electronic version of a one-way valve. ... The crystal radio receiver (also known as a crystal set) was first built circa 1900 by Greenleaf Whittier Pickard, who used crystalline minerals to detect radio signals. ...

The product detector multiplies the incoming signal by the signal of a local oscillator with the same frequency and phase as the carrier of the incoming signal. After filtering the original audio signal will result. This method will decode both AM and SSB, although if the phase cannot be determined a more complex setup is required. A product detector is a type of demodulator used for AM and SSB signals. ... SSB might be an acronym or abbreviation for: Single-sideband modulation strategic system builder Single-strand binding protein. ...

Frequency modulation or FM is more complex. It has numerous advantages over AM, such as better fidelity and noise immunity. However, it is much more complex to both modulate and demodulate a carrier wave with FM, and AM predates it by several decades. Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ...

There are several common types of FM demodulator:

The Quadrature detector, which phase shifts the signal by 90 degrees and multiplies it with the unshifted version. One of the terms that drops out from this operation is the original information signal, which is selected and amplified. Phase, from the Greek phasis, meaning appearance, has a number of related meanings in English. ...

The Foster-Seeley discriminator. The Foster-Seeley discriminator is an FM detector circuit that works on the same principle as most commonly used FM detectors, which is through variations in frequency. ...

The Phase-locked loop Many electronic systems use internal clocks which are required to be phase-aligned to and/or frequency multiples of some external reference clock. ...

In addition, demodulation can be accomplished using a digital signal processor, a technique used in software defined radio. A digital signal processor (DSP) is a specialized microprocessor designed specifically for digital signal processing, generally in real-time. ... A software-defined radio (SDR) system is a radio communication system which uses software for the modulation and demodulation of radio signals. ...