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It was used from about 1910 in a few "superpower" longwave radiotelegraphy stations to transmit transoceanic message traffic by Morse code to similar stations all over the world. Although superseded in the early 1920s by the development of vacuum-tube transmitters , the Alexanderson alternator continued to be used until World War II .
A receiver is tuned to a Morse code signal, and the receiver's intermediate frequency (IF) is f IF = 45000 Hz. That means the dits and dahs have become pulses of a 45000 Hz signal, which is inaudible. To make them audible, the frequency needs to be shifted into the audio range, for instance f audio = 1000 Hz.
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.
In order to transmit information with this signal, the operator turns the transmitter on and off rapidly by tapping on a switch called a telegraph key in the primary circuit of the transformer, producing sequences of short (dot) and long (dash) strings of damped waves, to spell out messages in Morse code. As long as the key is pressed the spark ...
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.
Morse code abbreviations are not the same as prosigns.Morse abbreviations are composed of (normal) textual alpha-numeric character symbols with normal Morse code inter-character spacing; the character symbols in abbreviations, unlike the delineated character groups representing Morse code prosigns, are not "run together" or concatenated in the way most prosigns are formed.
In Czech, the mnemonic device to remember letters in Morse code lies in remembering words or short phrases that begin with each appropriate letter and have a long vowel (i.e. á é í ó ú ý) for every dash and a short vowel (a e i o u y) for every dot. Additionally, some other sets of words with a particular theme have been thought up in ...
The Morse code, as specified in the current international standard, International Morse Code Recommendation, ITU-R M.1677-1, [1] was derived from a much-improved proposal by Friedrich Gerke in 1848 that became known as the "Hamburg alphabet", its only real defect being the use of an excessively long code ( and later the equal duration code ...