Limitations of coherers Coherer

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all fish came coherer net, , recorder wrote down dot , dash combinations quite impartially legitimate signals, static disturbances, slipping trolley several blocks away, , turning on , off of lights in building. translation of tape required brilliant imagination




coherers finicky adjust , not sensitive. problem that, because of cumbersome mechanical decohering mechanism, coherer limited receiving speed of 12 - 15 words per minute of morse code, while telegraph operators send @ rates of 50 wpm, , paper tape machines @ 100 wpm.


more important future, coherer not detect (radio) transmissions. simple switch registered presence or absence of radio waves, coherer detect on-off keying of wireless telegraphy transmitters, not demodulate (rectify) waveforms of radiotelephone signals, began experimented in first years of 20th century. problem solved rectification capability of reginald fessenden s hot wire barretter , electrolytic detector. these replaced crystal detector around 1906, , around 1912 vacuum tube technologies such john ambrose fleming s thermionic diode , lee de forest s audion (triode) tube.























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