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Beat frequency oscillator. 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 as a tone ...
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][4] Morse code is named after Samuel Morse, one of the early developers ...
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 ...
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 ...
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 ...
A few radios used a bulkier and more expensive motor-generator or motor-alternator set called a "dynamotor" that spun a high-voltage generator or alternator using a 6- or 12-volt DC motor. Filaments were powered using 6- and later 12-volt DC power from the vehicle's electrical system directly.
The Speech/Morse generator (pictured here) is a machine that has been used for many well-known numbers stations. The frequently reported use of high-tech modulations like data bursts, in combination or in sequence with spoken numbers, suggests varying transmissions for differing intelligence operations. [36]
Baudot developed his first multiplexed telegraph in 1872 [2] [3] and patented it in 1874. [3] [4] In 1876, he changed from a six-bit code to a five-bit code, [3] as suggested by Carl Friedrich Gauss and Wilhelm Weber in 1834, [2] [5] with equal on and off intervals, which allowed for transmission of the Roman alphabet, and included punctuation and control signals.