When I'm DXing in RTTY, I run a hardware TNC (KAM '98) and soundcard
RTTY simultaneously, using WinWarbler. I see the decoded text in two
windows; the resulting diversity decoding provides an incremental
advantage on difficult paths or under difficult conditions.
Alternatively, I can simultaneously decode a DX station and his or
her pileup when operating split.
73,
Dave, AA6YQ
--- In digitalradio@yahoogroups.com, list email filter <[EMAIL PROTECTED]>
wrote:
>
> Graeme,
>
> You've already got a couple of great answers, so I'll keep this
short.
> Really I can only think of 2 (maybe 3) reasons you might want to
run a
> hardware TNC as opposed to emulating the functionality in
soundcard
> based software.
>
> 1. You want (or need) to run Pactor. There really aren't any good
> soundcard emulators for that mode.
>
> 2. You want to install a stand-alone digipeater, bbs, and / or
gateway,
> i.e. doing this without a computer running. These days the only
people
> interested in this are the APRS folks, and with everyone wanting
to run
> an igate, even that's rare.
>
> 3. (This is less and less of an issue, but in the past it was a
> consideration...) Some soundcards aren't capable of supporting the
tnc
> emulating hardware. This is really only an issue with really old
> computers, some 'on the motherboard' soundcards, and some
laptops.
> Except for the case of the laptops, it is lots cheaper to solve
this
> issue by replacing a soundcard than it is to buy a hardware based
TNC.
> And even in the case of laptops there are work arounds that offer
more
> bang for the buck than a dedicated hardware TNC.
>
> In general, rather than buying a hardware TNC solution, you really
only
> need to buy or build a sound card interface, which connects audio
in /
> out, and ptt between your computer and radio. The 'brains' of the
> hardware TNC are completely replaced with software running on your
> computer.
>
> Btw, a TNC typically has several 'modems' built into it, its
largely a
> semantic issue, a carry over that goes back to the days when
terminal
> node controllers (TNCs) talked to PADs (packet assembler /
> disassemblers) which dealt with AX.25 (or X.25 for that matter),
and
> the modems were external. All of this functionality was
eventually
> bundled into one small box, and marketed to the Ham market as a
TNC.
> The, hardware changed over time, as more of the functionality was
taken
> on by the computer, which has us in our current state, where the
old
> hardware is largely deprecated, though don't try to convince an
RTTY
> die-hard of that (I'm typing this by the orange lcd glow of my 13
year
> old PK-900, which is more or less continuously decoding packet,
even
> when I shut the computer off).
>
> Sorry, I always jinx myself when I start out saying 'I'll keep
this
> short'. ;-)
>
> 73 and have fun!
>
> Erik
>
> KI4HMS/7
>
> PS. I just thought of another reason, it has to do with older
radios
> FSK capabilities / requirements (which will not be an issue with
your
> 857), and even those can be worked around if needed.
>
> On Feb 1, 2006, at 3:29 PM, zl1gbb wrote:
>
> > Can anyone help me out? I am just getting into digital modes.
Very
> > steep learning curve for my 67 year old brain. But I will manage
with a
> > little help. My problem is I do not understand the uses of the
> > equipment. My handbook on my radio (ft857d) shows that the radio
needs
> > a TNC to work various modes. Another source of information
suggests
> > that I should be using a modem (Baycom I think it is). Yet
another
> > suggests that at least some of this can be done with the sound
card in
> > my computer. But surely all these items are just variations on
the same
> > thing i.e. a method of applying audio signals to the baseband of
the
> > radio? What the heck does a TNC do that a modem does not? Or a
> > soundcard? If a soundcard can be used for PSK then its stability
must
> > be very high. So why can it not be substituted for the TNC?
> >
> > Proberly, the answer is quite obvious but it escapes me. Can
anyone
> > help?
> >
> > 73 Graeme zl1gbb
>
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