[RTTY] Omni-V and FSK

[Dave Bernstein]

Some RTTY applications and cluster interfaces, like WinWarbler and
SpotCollector, perform the proper arithmetic so that DX Spots generated
while operating in AFSK contain the correct mark frequency.

    73,

        Dave, AA6YQ

-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com]
On Behalf Of WA9ALS - John
Sent: Wednesday, April 02, 2003 9:46 PM
To: Ed; rtty at contesting.com
Subject: Re: [RTTY] Omni-V and FSK


Properly done, there's no discernable difference between FSK and AFSK.
In general, the difference is that in audioFSK, audio tones are used in
SSB mode to produce MARK and Space tones of 2125 and 2125+170 Hz).  In
FSK, the main oscillator is actually shifted between 2 frequencies 170
Hz apart. However, hardly any (?) new rigs actually shift the
oscillator.  For example, the Yaesu FT-1000MP "FSK" mode actually uses
an internal tone generator and thus is -really- AFSK, although offerring
the advantages listed below of FSK mode!

That said, there are still advantages to using "FSK", whether it's
"true" FSK or not.  Many older rigs using SSB mode for AFSK won't let
you use narrow filters in that mode.  However, they will let you use
narrow filters in FSK mode.

Using AFSK, you need everything set just right, ie you can easily
overdrive the rig with excess audio, producing a lousy, wide signal that
might not be printable and will certainly give you a bad reputation!
With more audio cables etc, using AFSK offers more opportunity for RFI.
With FSK, you are just supplying digital on and off signals to the rig
to shift or not shift the signal, and this is less prone to
interference.  Since you're not providing an audio signal, you can't
overdrive it.

And finally, my pet peeve, is that if you use AFSK, you will more likely
-not- be on frequency!  Most DX spots, skeds, etc are quoted in MARK
frequency. Depending on your rig and its setup, if you're using AFSK,
your dial will be off from the actual MARK frequency by 2125 Hz.  Thus
when you're contesting and see a spot for a hot mult at 1408300, you
might think he's not there.  However, you might actually find him at
14.081 (14.080875).  If you're on the other end and are the one doing
the spotting, people using FSK will not easily find your spots either
because they will be "off" by 2125 Hz.  When you're contesting and
running down
(up?) the band by clicking on bandmap spots, it's really great when the
signals are actually where they were spotted and where the rig QSYs.

AFSK is great for PSK, MFSK16, SSTV etc, but on RTTY, IMHO real
gentlemen use FSK.  HAHA - That's sure to start a controversy!  Just
kidding!  73 and have fun!
------------------------------------------------------------
John - WA9ALS - VP5RY (2001)

VP5 photos:  http://www.qsl.net/wa9als/vp5ryphotos.htm
     email:  wa9als at starband.net
  homepage:  http://www.wa9als.com

----- Original Message -----
From: "Ed" <edw3nr at nexband.com>
To: "RTTY" <rtty at contesting.com>
Sent: Wednesday, April 02, 2003 6:54 PM
Subject: [RTTY] Omni-V and FSK


>
> Just picked up an Omni-V and need some advice for setting up FSK. If I

> use MMTTY it still needs the soundcard for RX. I  set the default 
> encoding to "Ham" that uses the default normal ham settings for shift 
> and mark/space.
So
> what are the advantages to change to true FSK ??  I can use a PK 232 
> but lack a good terminal program for it. Just a newbie that is a 
> little confused. TIA.....73
>
> Ed W3NR
>
>
>
>
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