[Icom] IC-756pro
WA9ALS - John
[email protected]
Sat, 2 Mar 2002 09:22:26 -0500
> Another question while we are at it. I notice that between using the RTTY
> mode decode screen on the radio and a RigBlaster on LSB there is 2.2 kc
> difference in frequency. Is this nominal?
YES, and it's a very important concept to understand and master for both
your and others' enjoyment of RTTY (any "AFSK" mode, including PSK31)! The
RTTY mark tone is 2125Hz if you're using HIGH tones. This difference will
be noted on the displays of various rigs and modes somewhat differently,
i.e. some rigs have menu items that can adjust/correct for this difference.
This is one reason DX isn't where you think they are! Some people spot the
MARK frequency (the "right" way to do it), but many using RigBlasters and
other FSK solutions are spotting frequencies 2.125 KHz too high or low!
This is also why some people are transmitting out of band or on a dx calling
frequency or in a subband they don't intend to be in. They are -really-
transmitting 2.125 KHz higher or lower than where their SSB dial indicates!
If your rig can handle it, it's VERY desirable to operate RTTY in FSK mode
with the correct frequency display. The PRO, decoding in RTTY mode, is
showing you the REAL frequency. Using the RigBlaster in LSB is OK, but the
display will be off 2.125 KHz unless you have a menu item to correct for it,
and I don't think the PRO does.
Good luck - This usually requires some thinking and experimenting to "sink
in". One of the good things about RigBlasters and soundcard software is
that they've brought a lot of new people to the digital modes, so a big
WELCOME to you! However, some undesirable things include lots of people
using AFSK overdriving their soundcards and splattering all over the place,
and being off-frequency due to the above.
Have fun - best 73
------------------------------------------------------------
John - WA9ALS - VP5RY (2001)
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