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....