The scenario where neither A or B can hear C or D, but that C or D
are QRM'd by transmissions from A or B is indeed possible, but is
relatively infrequent. No one expects A or B -- whether they are
attended or unattended -- to suspend transmission to avoid QRMing a
station that neither can hear.
The more common scenario is that A can't hear C or D, but B can hear
C or D. A contacts B. If B is attended, he or she detects that the
frequency is in use, and either remains silent, or transmits
something quick like "QSY to 14085". If B is unattended and without a
busy frequency detector, its responds to A, QRMing C and D.
It is the latter scenario that is responsible for most of the QRM
from unattended stations responding to attended stations (often
referred to as "semi-automatic" operation). The fact that we can't
cure the first scenario is no excuse for not curing the second
scenario, especially given that the second scenario is far more
common than the first scenario.
73,
Dave, AA6YQ
--- In [email protected], "DuBose Walt Civ AETC CONS/LGCA"
<[EMAIL PROTECTED]> wrote:
>
> A & B hear each other but dont' hear C & D. But C hears either or
both A and B.
>
> If C is receiving D, then A or B is QRMing C.
>
> Walt/K5YFW
>
> -----Original Message-----
> From: [email protected]
> [mailto:[EMAIL PROTECTED] Behalf Of Danny Douglas
> Sent: Wednesday, December 13, 2006 12:22 PM
> To: [email protected]
> Subject: Re: [digitalradio] Re: Dec 15?
>
>
> HMMM By whom is C being QRMd. You didnt say who he is hearing as
QRM. I am
> assuming that C is hearing either A or B or even both? In this
case, if A
> and B were already in QSO, then C and D should QSY to start their
QSO
> elsewhere.
>
> If the C and D QSO was already underway, and A and B started up,
and they
> were not hearing either C or D (not probable as usually prop is two-
way if
> it is strong enough for QRM) then C and D would either put up with
it, or
> move since under this condition, they cant tell the other pair that
the freq
> is in use.
>
> It is prudent for both parties, starting a QSO to insure that
neither of
> them is intefering with an ongoing QSO, and by both checking to see
(both
> automatic stations having the capability) if the freq was QRL - it
would
> avoid inteference to others.
>
>
> Danny Douglas N7DC
> ex WN5QMX ET2US WA5UKR ET3USA
> SV0WPP VS6DD N7DC/YV5 G5CTB all
> DX 2-6 years each
> .
> QSL LOTW-buro- direct
> As courtesty I upload to eQSL but if you
> use that - also pls upload to LOTW
> or hard card.
>
> moderator [EMAIL PROTECTED]
> ----- Original Message -----
> From: "DuBose Walt Civ AETC CONS/LGCA" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Wednesday, December 13, 2006 12:56 PM
> Subject: RE: [digitalradio] Re: Dec 15?
>
>
> > If A and B can hear each other but can't hear C or D then if A or
B
> transmits and C is receiving D, then C is QRMed and can't copy D.
> >
> > This is something that happens quite often on HF and I don't
think that
> any amount of coding willremedy this problem.
> >
> > Walt/K5YFW
> >
> >
>
>
>
> Connect to telnet://cluster.dynalias.org a single node
spotting/alert system dedicated to digital and CW QSOs.
>
>
> Yahoo! Groups Links
>
