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In order to achieve both good adjacent channel selectivity and image rejection, the double-conversion receiver uses two intermediate frequencies (IFs). The incoming radio frequency (RF) signal from the antenna is first mixed with a sinusoidal signal from the 1st local oscillator (LO) to give a high 1st IF frequency.
English: Block diagram of a single conversion superheterodyne radio receiver. Invented by Edwin Armstrong in 1918 during World War 1, the superheterodyne is the design used in almost all modern radio receivers.
Block diagram of a typical superheterodyne receiver. Red parts are those that handle the incoming radio frequency (RF) signal; green are parts that operate at the intermediate frequency (IF), while blue parts operate at the modulation (audio) frequency.
A 5-tube superheterodyne receiver manufactured by Toshiba circa 1955 Superheterodyne transistor radio circuit circa 1975. A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency.
Block diagram of a superheterodyne receiver. The RF front end consists of the components on the left colored red. In a radio receiver circuit, the RF front end, short for radio frequency front end, is a generic term for all the circuitry between a receiver's antenna input up to and including the mixer stage. [1]
English: Block diagram of a tuned radio frequency (TRF) receiver, the simplest type of amplifying radio receiver circuit. It consists of one or more tuned RF amplifiers, each consisting of a tuned circuit which functioned as a bandpass filter followed by a radio frequency (RF) amplifier; a detector (demodulator) to extract the audio waveform from the radio carrier wave; followed by an audio ...
A crystal set receiver consisting of an antenna, a variable inductor, a cat's whisker, and a filter capacitor. A crystal receiver is very simple and can be easy to make or even improvise, for example, the foxhole radio. However, the crystal radio needs a strong RF signal and a long antenna to operate.
English: Block diagram of a tuned radio frequency (TRF) receiver, a type of radio receiver circuit invented in 1916 by Ernst Alexanderson and widely used in the vacuum tube receivers of the 1920s.