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The mixer is called the first detector, while the demodulator that extracts the audio signal from the intermediate frequency is called the second detector. In microwave and millimeter wave technology the terms detector and crystal detector refer to waveguide or coaxial transmission line components, used for power or SWR measurement, that ...
The detector stage recovers the information from the radio-frequency signal, and produces the sound, video, or data that was impressed on the carrier wave initially. Detectors may be as simple as an "envelope" detector for amplitude modulation , or may be more complex circuits for more recently developed techniques such as frequency-hopping ...
The crystal detector demodulates the radio frequency signal, extracting the modulation (the audio signal which represents the sound waves) from the radio frequency carrier wave. In early receivers, a type of crystal detector often used was a "cat whisker detector".
An electro-optical detector is used to measure the intensity of the light, which is then normally displayed on a screen in a similar manner to a radio- or audio-frequency spectrum analyzer. The input to an optical spectrum analyzer may be simply via an aperture in the instrument's case, an optical fiber or an optical connector to which a fiber ...
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.
Most audio compression techniques will make radical changes to the binary encoding of an audio file, without radically affecting the way it is perceived by the human ear. A robust acoustic fingerprint will allow a recording to be identified after it has gone through such compression, even if the audio quality has been reduced significantly.
Sound recognition is a technology, which is based on both traditional pattern recognition theories and audio signal analysis methods. Sound recognition technologies contain preliminary data processing, feature extraction and classification algorithms. Sound recognition can classify feature vectors.
There are many methods available and beat detection is always a tradeoff between accuracy and speed. Beat detectors are common in music visualization software such as some media player plugins. The algorithms used may utilize simple statistical models based on sound energy or may involve sophisticated comb filter networks or other