The difference is in the concept of 'carrier suppressed'. I'm not up to
speed on DSP implementations, but with the traditional analog
implementations, the carrier and opposite sideband are still present in the
signal, though greatly attenuated. With true FSK, the radio only generates
two different RF tones. Another issue may be the transitions between the
tones. I don't know if the waveform of perfectly modulated AFSK would have
the same transients in the transitions.
That being said, my Omni VI is in need of a slight alignment ( I need to get
a freq counter ). I noticed that when monitoring its FSK signal on a second
receiver, the tones were only about 130 Hz apart. When I feed AFSK to the
radio, the tones were a perfect 170 Hz apart.
----- Original Message -----
From: "James Duffer" <firstname.lastname@example.org>
Sent: Friday, April 04, 2003 9:09 AM
Subject: Re: [TenTec] Fw: Orion
> Please explain the difference between "true Frequency Shift Keying and the
> pseudo FSK as generated by the Orion (and others). It seems to me that if
> in truly carrier suppressed SSB signal that is moulated by a pair of
> sinusoid audio tones the ouput would appear to alternate in frequency by
> frequency difference of the two audio tones.
> What does the receiver get that is different from true FSK and the other
> >From: John L Merrill <email@example.com>
> >Reply-To: firstname.lastname@example.org
> >To: email@example.com
> >Subject: [TenTec] Fw: Orion
> >Date: Thu, 03 Apr 2003 23:30:17 -0500
> >I'm afraid I'll join Rog on the FSK issue. I'm a rtty purist. I'm
> >disappointed there is no true fsk on the Onion. Seems like Kenwood and
> >are the only ones that care about fsk. Yaesu does the keyed afsk way.
> >issue may hold me back from ordering one.
> >John N1JM
> >TenTec mailing list
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