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  2. Morse code - Wikipedia

    en.wikipedia.org/wiki/Morse_code

    Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. [3] [4] Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy . International Morse code encodes the 26 ...

  3. Beat frequency oscillator - Wikipedia

    en.wikipedia.org/wiki/Beat_frequency_oscillator

    Add-on 455 kHz homemade BFO board. In a radio receiver, a beat frequency oscillator or BFO is a dedicated oscillator used to create an audio frequency signal from Morse code radiotelegraphy ( CW) transmissions to make them audible. The signal from the BFO is mixed with the received signal to create a heterodyne or beat frequency which is heard ...

  4. Numbers station - Wikipedia

    en.wikipedia.org/wiki/Numbers_station

    A recording of The Gong numbers station, run by the National People's Army of the German Democratic Republic, from 1988. A numbers station is a shortwave radio station characterized by broadcasts of formatted numbers, which are believed to be addressed to intelligence officers operating in foreign countries. [1]

  5. American Morse code - Wikipedia

    en.wikipedia.org/wiki/American_Morse_code

    American Morse code. American Morse Code — also known as Railroad Morse—is the latter-day name for the original version of the Morse Code developed in the mid-1840s, by Samuel Morse and Alfred Vail for their electric telegraph. The "American" qualifier was added because, after most of the rest of the world adopted " International Morse Code ...

  6. Russian Morse code - Wikipedia

    en.wikipedia.org/wiki/Russian_Morse_code

    MTK-2. v. t. e. The Russian Morse code approximates the Morse code for the Latin alphabet. It was enacted by the Russian government in 1856. [1] [2] To memorize the codes, practitioners use mnemonics known as напевы (loosely translated "melodies" or "chants"). The "melody" corresponding to a character is a sung phrase: syllables ...

  7. Slow-scan television - Wikipedia

    en.wikipedia.org/wiki/Slow-scan_television

    Slow-scan television ( SSTV) is a picture transmission method, used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color. A literal term for SSTV is narrowband television. Analog broadcast television requires at least 6 MHz wide channels, because it transmits 25 or 30 picture frames per ...

  8. Modulated continuous wave - Wikipedia

    en.wikipedia.org/wiki/Modulated_continuous_wave

    v. t. e. Modulated continuous wave (MCW) is Morse code telegraphy transmitted using an audio tone to modulate a carrier wave . Continuous wave (CW), by contrast, does not use a subcarrier, so there is no emission at all between Morse code symbols. MCW can be generated by any AM or FM radio transmitter with audio input from an audio oscillator ...

  9. Telegraph sounder - Wikipedia

    en.wikipedia.org/wiki/Telegraph_sounder

    Telegraph Sounder. A telegraph sounder is an antique electromechanical device used as a receiver on electrical telegraph lines during the 19th century. It was invented by Alfred Vail after 1850 to replace the previous receiving device, the cumbersome Morse register [1] and was the first practical application of the electromagnet.