[Scan-DC] Fairfax County Public Safety

[Andy]

Hi  guys,

I've been following this thread and unfortunately we've been missing the
boat on this.  This is not a problem, the scanner is functioning correctly.
There is NO need to reset either unit.

What you're seeing is a result of the status bit.  Go into your settings and
change it so the status bit setting is ON.  When the receiver lands on the
supposed 17623 talkgroup with the status bit on, then the real talkgroup
will show on the scanner's display.  17623 I believe is 17616 which is TG 4A
Fire Dispatch.  This is all you need to do.

So again, do not reset your radios, there is no reason to do so!

Brought to you and everyone else as a public service for those who may not
understand the status bit by me.

To read up on what the status bit is and what it does please read the
following directly quoted from TrunkedRadio.Net:

The following is available at:

http://www.trunkedradio.net
Look under the left hand column for System Info.  From there choose
Motorola, once that frame comes up on your screen then scroll down until you
see Type II System Special Status Bits (Its the 5th section down).

Type II Smartnet systems use these status bits for special transmissions
such as Emergency, Patches, DES/DVP scrambled transmissions, and
Multiselects on Motorola Trunking systems. Motorola Trunking radios directly
interpret them for their special functions, thus no difference is noticed by
the person with the radio. The Trunktracker scanners however interpret these
special talkgroup status bits as different talkgroups entirely. Below is the
conversion chart for these special status bits.


      TTID + # Usage
      ID+0 Normal Talkgroup
      ID+1 All Talkgroup
      ID+2 Emergency
      ID+3 talkgroup patch to another
      ID+4 Emergency Patch
      ID+5 Emergency multi-group
      ID+6 Not assigned
      ID+7 Multi-select (initiated by dispatcher)
      ID+8 DES Encryption talkgroup
      ID+9 DES All Talkgroup
      ID+10 DES Emergency
      ID+11 DES Talkgroup patch
      ID+12 DES Emergency Patch
      ID+13 DES Emergency multi-group
      ID+14 Not assigned
      ID+15 Multi-select DES TG

Therefore, if a user was transmitting a multi-select call on talkgroup 1808,
the trunktracker would actually receive those transmissions on 1815. Some
common uses of these status bits are as follows:

  a.. When a user hits their emergency button, all conversations on the
talkgroup revert to the Emergency status talkgroup (ID+2) until the dispatch
clears the emergency status. Therefore, if someone hit their emergency
button and their radio was on talkgroup 16, all communications would switch
to talkgroup 18.
  b.. A lot of Fire and EMS departments dispatch tone-outs and alarms as
Multi-select communications (ID+7). Therefore, if your fire department
dispatch talkgroup is 1616, and they do dispatch tone-outs and alarms as
Multi-selects, then those communications will be on talkgroup 1623.
This can be a problem, because you will miss communications if you don't
have those talkgroups programmed. By setting the Type II block you are
monitoring with a fleetmap of S-1 (Mot Size A), you'll essentially get Type
I subfleets for each Type II talkgroup - encompassing all of the status bits
into one subfleet.


> > >From: "John M. Nash" <j.m.nash@verizon.net>
> > >To: <scan-dc@mailman.qth.net>
> > >Subject: [Scan-DC] Fairfax County Public Safety
> > >Date: Wed, 23 Apr 2003 08:26:11 -0400
> > >
> > >Good morning:
> > >
> > >After a couple of days of monitoring the Fairfax County system, I would
> > >like to start confirming some of the talkgroup information.  I
programmed
> > >the current posted information from trunkedradio.net. Most of the
> > >information is correct.  Some might be in error. For instance, it has
> FCFD
> > >4A as 17616. I found it on 17623.  Talkgroup 17648 does appear to be
FCFD
> > >4B.  I have not heard any traffic on the talkgroups 17680 (4C) 17712
(4D)
> > >or 17744 (4E). Are these good talkgroups for the fireground channels?