heterodyne receiver การใช้

• After vacuum tube oscillators were invented in 1913 by Alexander Meissner the heterodyne receiver replaced the tikker.
• But quenching with overtones acts further as a heterodyne receiver mixing additional unneeded signals from those bands into the working frequency.
• Around 1915 the tikker was replaced by a better means of accomplishing the same thing; the " heterodyne receiver " invented by Reginald Fessenden in 1902.
• Another advantage of the circuit was that the tube could be made to oscillate, and thus a single tube could serve as both a beat frequency oscillator and a detector, functioning as a heterodyne receiver to make CW radiotelegraphy transmissions audible.
• Examples of detectors common in spectroscopy include heterodyne receivers in the microwave, bolometers in the millimeter-wave and infrared, mercury cadmium telluride and other cooled semiconductor detectors in the infrared, and photodiodes and photomultiplier tubes in the visible and ultraviolet.