> I thought you may be interested to know your RTTY signal was 450 hz
> wide
> vice the 'normal' 170 hz.
A normal RTTY signal has a shift of 170 Hz, but the -30 dB points are
normally about 350 Hz to 450 Hz wide (even wider if you are using an
FSK rig that has keyclicks).
The mystery deepens since it turns out that 450 Hz shift (mark tone
is 450 Hz away from space tone) *is* one of the standards used in
radioteletype, just not used by hams.
Hams usually stick to 170 Hz or 850 Hz shifts, the latter at 75 baud.
So, if we assume that your signal *did* change to 450 Hz shift, the
next question is were you using FSK or AFSK?
If you were using AFSK, it is some software in your computer that was
responsible. But if your were using FSK, then only your rig can be
responsible for the wider shift.
A software modem could not have caused an FSK rig to change shift,
since all the software does is to send the rig an FSK keying signal,
although potentially some rig control software could have made the
accidental switch.
73
Chen, W7AY
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