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  2. Morse code - Wikipedia

    en.wikipedia.org/wiki/Morse_code

    Chart of the Morse code 26 letters and 10 numerals [1]. This Morse key was originally used by Gotthard railway, later by a shortwave radio amateur [2]. Morse code is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs.

  3. PSK31 - Wikipedia

    en.wikipedia.org/wiki/PSK31

    A waterfall display depicting several PSK31 transmissions at around 14,070 kHz. The green lines indicate a station that is transmitting. PSK31 or "Phase Shift Keying, 31 Baud", also BPSK31 and QPSK31, is a popular computer-sound card-generated radioteletype mode, used primarily by amateur radio operators to conduct real-time keyboard-to-keyboard chat, most often using frequencies in the high ...

  4. 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 ...

  5. Morse code mnemonics - Wikipedia

    en.wikipedia.org/wiki/Morse_code_mnemonics

    Morse code mnemonics are systems to represent the sound of Morse characters in a way intended to be easy to remember. Since every one of these mnemonics requires a two-step mental translation between sound and character, none of these systems are useful for using manual Morse at practical speeds. Amateur radio clubs can provide resources to ...

  6. Fldigi - Wikipedia

    en.wikipedia.org/wiki/Fldigi

    Fldigi (short for Fast light digital) [4] is a free and open-source program which allows an ordinary computer's sound card to be used as a simple two-way data modem.The software is mostly used by amateur radio operators who connect the microphone and headphone connections of an amateur radio SSB or FM transceiver to the computer's headphone and microphone connections, respectively.

  7. Heterodyne - Wikipedia

    en.wikipedia.org/wiki/Heterodyne

    When these damped waves were received by a simple detector, the operator would hear an audible buzzing sound that could be transcribed back into alpha-numeric characters. With the development of the arc converter radio transmitter in 1904, continuous wave (CW) modulation began to be used for radiotelegraphy. CW Morse code signals are not ...

  8. Continuous wave - Wikipedia

    en.wikipedia.org/wiki/Continuous_wave

    t. e. A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency, typically a sine wave, that for mathematical analysis is considered to be of infinite duration. [1] It may refer to e.g. a laser or particle accelerator having a continuous output, as opposed to a pulsed output.

  9. Crystal radio - Wikipedia

    en.wikipedia.org/wiki/Crystal_radio

    The earliest practical use of crystal radio was to receive Morse code radio signals transmitted from spark-gap transmitters by early amateur radio experimenters. As electronics evolved, the ability to send voice signals by radio caused a technological explosion around 1920 that evolved into today's radio broadcasting industry.