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  2. Morse code - Wikipedia

    en.wikipedia.org/wiki/Morse_code

    Morse code. 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] [4] Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy .

  3. Survival radio - Wikipedia

    en.wikipedia.org/wiki/Survival_radio

    AN/PRC-90-1 and AN/PRC-90-2 are improved, repairable versions. Operates on 243 and 282.8 MHz AM. The PRC-90 also included a beacon mode, and a tone generator to allow the sending of Morse Code. [8] [9] AN/PRC-103 - (Air Force) Rescue Swimmer Radio. [8] [10] AN/PRC-112 - Offers Synthesized radio in the VHF and UHF aircraft bands.

  4. 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 ...

  5. Underwater acoustic communication - Wikipedia

    en.wikipedia.org/wiki/Underwater_acoustic...

    Underwater acoustic communication is a technique of sending and receiving messages in water. [ 1] There are several ways of employing such communication but the most common is by using hydrophones. Underwater communication is difficult due to factors such as multi-path propagation, time variations of the channel, small available bandwidth and ...

  6. Spark-gap transmitter - Wikipedia

    en.wikipedia.org/wiki/Spark-gap_transmitter

    The spark gap is inside the box with the transparent cover at top center. A spark-gap transmitter is an obsolete type of radio transmitter which generates radio waves by means of an electric spark. [ 1][ 2] Spark-gap transmitters were the first type of radio transmitter, and were the main type used during the wireless telegraphy or "spark" era ...

  7. 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 ...

  8. Prosigns for Morse code - Wikipedia

    en.wikipedia.org/wiki/Prosigns_for_Morse_code

    The procedure signs below are compiled from the official specification for Morse Code, ITU-R M.1677, International Morse Code, [1] while others are defined the International Radio Regulations for Mobile Maritime Service, including ITU-R M.1170, [8] ITU-R M.1172, [4] and the Maritime International Code of Signals, [5] with a few details of their ...

  9. Clansman (military radio) - Wikipedia

    en.wikipedia.org/wiki/Clansman_(military_radio)

    Clansman (military radio) Clansman is the name of a combat net radio system (CNR) used by the British Army from 1976 to 2010. Clansman was developed by the Signals Research and Development Establishment (SRDE) in the 1960s, to satisfy a General Staff Requirement (GSR) laid down in 1965. Clansman represented a considerable advance over existing ...