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Envelope Detection
An envelope detector (sometimes called a peak detector) is an electronic circuit that takes a (relatively) high-frequency signal as input and outputs the ''envelope'' of the original signal. Diode detector A simple form of envelope detector used in detectors for early radios is the diode detector. Its output approximates a voltage-shifted version of the input's upper envelope. Between the circuit's input and output is a diode that performs half-wave rectification, allowing substantial current flow only when the input voltage is around a diode drop higher than the output terminal. The output is connected to a capacitor of value C and resistor of value R in parallel to ground. The capacitor is charged as the input voltage approaches its positive peaks. At other times, the capacitor is gradually discharged through the resistor. The resistor and capacitor form a 1st-order low pass filter, which attenuates higher frequencies at a rate of -6 dB per octave above its cutoff fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C Envelope Follower
C, or c, is the third letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''cee'' (pronounced ), plural ''cees''. History "C" comes from the same letter as "G". The Semites named it gimel. The sign is possibly adapted from an Egyptian hieroglyph for a staff sling, which may have been the meaning of the name ''gimel''. Another possibility is that it depicted a camel, the Semitic name for which was ''gamal''. Barry B. Powell, a specialist in the history of writing, states "It is hard to imagine how gimel = "camel" can be derived from the picture of a camel (it may show his hump, or his head and neck!)". In the Etruscan language, plosive consonants had no contrastive voicing, so the Greek ' Γ' (Gamma) was adopted into the Etruscan alphabet to represent . Already in the Western Greek alphabet, Gamma first took a '' form in Early Etruscan, then '' in Classical Et ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Signal
Radio waves (formerly called Hertzian waves) are a type of electromagnetic radiation with the lowest frequencies and the longest wavelengths in the electromagnetic spectrum, typically with frequencies below 300 gigahertz (GHz) and wavelengths greater than , about the diameter of a grain of rice. Radio waves with frequencies above about 1 GHz and wavelengths shorter than 30 centimeters are called microwaves. Like all electromagnetic waves, radio waves in vacuum travel at the speed of light, and in the Earth's atmosphere at a slightly lower speed. Radio waves are generated by charged particles undergoing acceleration, such as time-varying electric currents. Naturally occurring radio waves are emitted by lightning and astronomical objects, and are part of the blackbody radiation emitted by all warm objects. Radio waves are generated artificially by an electronic device called a transmitter, which is connected to an antenna, which radiates the waves. They are received ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
