This looks like another proof that busy detection is feasible with
soundcard software. If you don't mind, Andy, please check its ability
to detect CW and RTTY.
The difference between asking "is this frequency in use?",
sending "QRL?" in CW, and an ALE sounding is that few human operators
will recognize the latter, much less decode it rapidly enough to
respond. "QRL?" in CW is something that human operators either
already know or could easily learn to recognize; it'd be an effective
way for automatic stations to actively determine whether a frequency
is already in use.
As for Winlink, most Winlink users employ a TNC that does not support
busy detection. Had SCAMP worked, and had someone developed a forcing
function to drive Winlink users off those TNCs and onto SCAMP, then
busy detection would be available in WinLink too.
73,
Dave, AA6YQ
--- In digitalradio@yahoogroups.com, "Andrew O'Brien"
<[EMAIL PROTECTED]> wrote:
>
> Within PC-ALE there is a setting called "Voice Detect", I had not
> checked that box. I can confirm that with that box checked PC-ALE
> never transmitted when scanning 550, 740 and 860 KHZ.
>
> I then modified my settings to scan frequencies with lower signal
> levels, 7120, 10000, and 14300. PC-ALE transmitted on 7120 , no
> signal present, but did not transmit on WWV's freq or on 14300.
>
> I need to play around more but it seems so far that PC-ALE does NOT
> transmit if the frequency is busy. How Charles accomplished this but
> the Winlink 2000 folks did not, is puzzling to me.
>
> If the frequency sounds clear but actually is not (perhaps one end
of
> a QSO is not audible but the other will be when it is there turn) ,
> what would be the difference between someone on SSB saying "is this
> frequency in use ?" and an ALE sounding? They both last about the
> same time. If one uses PSK31 or something like Olivia , sending "is
> this frequency in use?" would actually take longer than an ALE
> sounding.
>
> I can't join the "channelizing" debate because I don;t quite get it,
> but the early results are that PC-ALE does not transmit if a signal
is
> present. I think I will next test 14070 14075 and see if PC-ALE
> detects PSK31 and other digital modes and avoids transmitting.
>
>
> Andy K3UK
> Fredonia, New York.
> Skype Me : callto://andyobrien73
> Also available via Echolink
>
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