Superheterodyne receiver

A radio receiver that mixes an incoming signal with a local oscillator to produce a fixed intermediate frequency for filtering and amplification.

Frequency mixer: A circuit that combines signals to produce components at their sum and difference frequencies. It translates the selected radio signal to the receiver’s intermediate frequency.
Heterodyning: The production of new frequencies by combining two oscillating signals in a nonlinear device. The receiver applies heterodyning to shift the station signal to a fixed frequency.
Edwin Howard Armstrong: An American electrical engineer who developed key radio technologies, including the superheterodyne receiver. Armstrong introduced the superheterodyne method during World War I.
Tuned radio frequency receiver: A receiver that amplifies and filters a signal at its received radio frequency rather than converting it first. It must tune several stages together, unlike the superheterodyne’s fixed-frequency processing.
AM radio receiver: A radio receiver designed to recover amplitude-modulated broadcast signals. Many conventional AM broadcast receivers use a superheterodyne signal chain.
Local oscillator: An oscillator that generates a signal at a controlled frequency for use within an electronic system. Its frequency determines which incoming station converts to the chosen intermediate frequency.
Resonance: A condition in which a system responds strongly to oscillation near one of its natural frequencies. Tuned resonant circuits select radio frequencies and help reject unwanted signals.
World War I radio: Radio communication technologies and practices used during the First World War. Military needs for reliable reception provided the setting for Armstrong’s receiver design.
Direct-conversion receiver: A receiver that mixes a radio signal directly to zero or near-zero frequency for processing. It avoids a conventional intermediate frequency but faces distinct baseband and oscillator challenges.
FM radio receiver: A receiver designed to recover information encoded by frequency modulation. Superheterodyne conversion enables fixed-frequency filtering in many FM broadcast receivers.

Linked from 5 pages