[TrunkCom] EDACS System Questions

[Gary Hahn]

I think Jeff may be on the right track.

1.  My theory.  You're not hearing the control channel but EDACS MDT data.
There are certain freq channels with this capability, so you may notice that
it happens only on certain freqs.  I think that real radios know to either
listen for dotting (beeeeep, beep, beep) at the end of transmission, or this
data.  I suspect that when there is data in the queue for a given freq, it
is transmitted immediately after a voice transmission ends without waiting
for the dotting.  I wonder if the trunktrackers sometimes miss because of
this.

2.  Several EDACS systems have periodic test transmissions, just about 3
seconds of carrier followed by dotting.  Could be the scanner is snagging
that on occasion by accident?

3.  You have to tell the BC780 to track I-calls before it will.  Consult the
manual.  Nearest system to me makes extensive...almost to the point of
absurdity...use of this function.

>
> I think that this could be some kind of data.  'I've noticed
> on an EDACS
> system in my area that it will make that noise, but not
> consistently.  It
> might be something that has to do with being on the fringes
> of a coverage
> area. Sometimes too, if you listen in conventional mode
> you'll hear that
> noise as well with no voie to fololow.
>
>
> On Sat, 25 May 2002, Justin W. Pauler wrote:
>
> > To Everyone:
> >
> > I live in La Grange, TX and our sheriffs department and all
> of the local
> > police departments in our county, Fayette County, are part
> of the LCRA
> > Wide Area Radio System. This system is an EDACS system with
> many towers
> > throughout central Texas.
> >
> > My questions are these:
> >
> > 1. Every once-and-awhile, you will hear a few seconds of the data
> > channel come across on one of the voice channels and then
> disappears.
> > The data seems to come across our dispatch talk group and
> is sometimes
> > followed by voice traffic, but not always. I am sure it
> isn't a problem
> > with my radio as I was in Radio Shack the other day and my
> scanner along
> > with three other displays caught it at the same time. It
> seems this is
> > some type of data being transmitted as none of the units in
> the patrol
> > cars nor the handhelds are picking it up. Any ideas?
> >
> > 2. Some of the traffic is followed by a period of white
> space. You can
> > hear the end of the transmission, but the carrier stays
> open for a few
> > seconds longer. This creates a problem because while your scanner is
> > stuck on this white space, the unit is replying to the
> transmission on
> > another channel. Several people in this area are hearing
> the same thing
> > and it is not because of the delay feature.
> >
> > 3. Finally, does anyone have any idea about where I-Call's are
> > transmitted? All of the units in our county have this
> option, but I have
> > only one time been able to catch them talking and I did not
> remember to
> > write down where I heard it. The new uniden radio says it is able to
> > track I-Calls, so I do believe it is out there. I have
> opened my radio
> > to search all of the talk groups when I am sure that they
> are talking on
> > the I-Call feature, but I can never pick anything up.
> Anyone have any
> > luck with this?
> >
> > I would appreciate any help anyone could give. I am looking
> forward to
> > scanning the systems in our county reliably after I get
> over these few
> > humps. In case it matters, I am scanning with a Radio Shack Pro-94.
> >
> > -- jwp
> >
> > Justin W. Pauler <justin@jwpauler.org>
> >
> >
> > _______________________________________________
> > TrunkCom mailing list
> > mailto:TrunkCom@mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/trunkcom
> >
>
>
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