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Ok lets simplifies it
From URL: http://wombat.doc.ic.ac.uk/foldoc/fo...y+Shift+Keying communications (FSK) The use of frequency modulation to transmit digital data, i.e. two different carrier frequencies are used to represent zero and one. FSK was originally used to transmit teleprinter messages by radio (RTTY) but can be used for most other types of radio and land-line digital telegraphy. More than two frequencies can be used to increase transmission rates. Also URL: http://www.its.bldrdoc.gov/fs-1037/dir-016/_2347.htm frequency-shift keying (FSK): Frequency modulation in which the modulating signal shifts the output frequency between predetermined values. (188) Note 1: Usually, the instantaneous frequency is shifted between two discrete values termed the "mark" and "space" frequencies. This is a noncoherent form of FSK. Note 2: Coherent forms of FSK exist in which there is no phase discontinuity in the output signal. Synonyms frequency-shift modulation, frequency-shift signaling. Also see URL: http://searchnetworking.techtarget.c...213936,00.html Frequency-shift keying (FSK) is a method of transmitting digital signals. The two binary states, logic 0 (low) and 1 (high), are each represented by an analog waveform. Logic 0 is represented by a wave at a specific frequency, and logic 1 is represented by a wave at a different frequency. A modem converts the binary data from a computer to FSK for transmission over telephone lines, cables, optical fiber, or wireless media. The modem also converts incoming FSK signals to digital low and high states, which the computer can "understand." -- 73 From The Signal In The Noise Caveat Lector Ya All --------------------------------------------------- "Mike W" wrote in message ... On Tue, 9 Sep 2003 08:40:41 -0700, "Caveat Lector" wrote: From URL: http://www.tpub.com/content/neets/14...s/14184_94.htm FSK SIGNALS.-In fsk the rf signal is shifted in frequency (not amplitude) between "key-open" and "key-closed" conditions. The signal amplitude remains essentially constant. View (A) of figure 2-3 represents the letter "F" keyed as a shift in frequency between mark and space. The normal frequency condition with the key open is a space. Recall that this may be either the lower or higher frequency. When the key is closed, the frequency instantly changes to the mark value and remains constant during the marking interval. Opening the key again returns the frequency to the space frequency. Midway between the mark and space frequencies is the assigned channel frequency AFSK signals are at URL: http://www.ik3qar.it/rtty/3/ -- 73 From The Signal In The Noise Caveat Lector Ya All Damn, I thought I had received a definitave answer, and now I get a contrary view... ;-( goes away muttering untypeable utterances.... |