Mike-39 wrote:
>
>
> Re: PSK/direct earlier... Copied from the K3 user manual
>
> "Modes USB, LSB, AM, FM, CW, and DATA. In DATA mode: FSK D (Direct), AFSK
> A
> (Audio), PSK D (Direct) and DATA A (Audio; PSK, etc.). Built in PSK,
> RTTY, and
> CW text decode/display."
>
> What I mean by offset is having to tune xnnn Hz up/down from the carrier
> frequency. I'ts just one more mental step that slows me down, and it's
> un-necessary. I don't understand what your comment about the 400-2400Hz
> means, unless it's the offset I'm talking about. I've never operated
> AFSK, so I may be using the wrong terminology.
>
>
I don't know about unusually difficult. Certainly not as easy as using AFSK
(as even the article you referred to stated) as it requires a special
interface and extra connections to the ACC connector. But if that's the way
you want to do it, I think Joe has given you the answer.
RTTY was traditionally generated by directly frequency shifting the carrier
because the two tones directly correspond to the state 1 or 0 of the serial
data stream when text is transmitted using 5-bit ASCII at 45.5 baud. PSK31
is a more complicated modulation scheme. According to the manual, the K3 can
generate PSK31 using FSK IN as well. That is something unique to the K3 and
I don't know what software supports that method of doing it or whether
anyone has ever tried it. The manual doesn't state what bit length / baud
rate you must use in that case.
The reason I don't use the direct method is that I simply find it far easier
to tune a signal in by clicking with the mouse on a waterfall display
anywhere within the 400 - 2400Hz range of the passband (or whatever filter
width you are using) and letting the software AFC ensure you are accurately
netted than using the VFO to tune the signal to the precise frequency that
is used when the mode is generated directly. I appreciate that you may be
used to working RTTY that way (I did too, in the years before sound cards)
but having got used to using a waterfall for PSK31 the old way of doing it
just seems unnecessarily difficult (and it's much harder to tune in a PSK
signal using the VFO than a RTTY one.)
-----
Julian, G4ILO. K2 #392 K3 #222.
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html
--
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