There are two considerations:
1. the signal being decoded should fall within the receive filter(s)
you're using. Some ops activate RTTY or CW filters during PSK QSOs;
their choise of offset is thus limited by the positioning of these
filters within their receiver's bandpass.
2. the second harmonic of your transmit audio tone should fall
outside your transmitter's bandpass (to minimize QRM)
So if your transmitter's bandpass extends to 2.7 kHz, an audio offset
of 1600 or 1700 is ideal -- assuming a signal at that offset will
pass the filter you use during reception.
Many digital mode applications -- including MixW -- have the
capability to QSY your transceiver to achieve a pre-specified audio
offset. This lets you select a signal in the waterfall with one
action, decide you're interested, and then QSY your transceiver with
a second action before making your call using the optimal audio
offset.
73,
Dave, AA6YQ
--- In digitalradio@yahoogroups.com, Bill Aycock <[EMAIL PROTECTED]> wrote:
>
>
> Frank- I think that there is MUCH confusion in our ranks on this
> subject. For instance, I set my rig to one frequency (usually
> 14,070.00) and leave it there. I tune to different signals by
moving
> the "marker" that shows the offset from the base frequency on the
waterfall.
> The radio bandwidth is many times as wide as the signal width (for
> PSK31), and many signals can be accommodated in the passband. I
have
> a tuneable Digital filter, and one of the most educational tricks
is
> to shift the upper and lower audio limits of the filter, and watch
> the result on the waterfall
> One of the sources of the confusion is the ambiguity in the meaning
> of "best". I think that it is highly improbable that we can get a
> clear definition.
> Good luck- Bill-W4BSG
>
> At 10:27 PM 9/4/2007, you wrote:
> >Hey group, this is Frank K2NCC,
> >
> >Just wanted to ask what is surely a noobie question or two.
> >
> >If my waterfall (using MixW) can receive a signal between 300KHz
and
> >3000KHz on the spectrum, that's my bandwidth of the radio, right?
> >Seems to match what the manual says, 2700.
> >
> >I've read where PSK31 is best at 1000KHz on the audio marker in a
QSO.
> >But, one could QSO pretty far on either side of that line if you
> >avoid the fringes. Right?
> >
> >Oh, if it matters, the radio is TS-830S and a Signalink.
> >
> >Well, the halfway point on the waterfall for me is about 1650 on
the
> >audio marker.
> >
> >I'm guessing that whatever frequency I'm on when I tune the signal
to
> >that 1650 point, is the frequency they're transmitting on. I asked
> >and have been very close, but can only hope that my rig is on the
> >mark. Either way, it's not been off by more than 3Hz. Since the
rig
> >only has six digit display, I round it off anyway.
> >
> >Is that the best place to transmit and receive? Dead center of the
> >frequency seems to be the ideal place if both sides are doing the
same.
> >
> >73. Frank K2NCC
> >
> >
> >
> >Announce your digital presence via our Interactive Sked Page at
> >http://www.obriensweb.com/drsked/drsked.php
> >
> >Yahoo! Groups Links
> >
> >
> >
>
> We batter this Planet as if we had someplace else to go.
>
