Thanks Dave.  Has anyone been able to monitor this kind of a system?  I'm
not going to invest in trunktracking it until I can actually find out who
is using it and is it worthy of spending t e money for a kit that I guess
you can trunktrack these kinds of systems?





On Sat, 23 Oct 2004, Dave Marthouse wrote:

> Jeff,
>
> >From what I understand about the 220/222MHZ band, it is divided into 5KHZ
> channels.  The mode that is used for voice communications is acsb (amplitude
> commanded single sideband).  Acsb is a standard ssb signal that is
> compressed.  There is also a pilot tone inserted 3.1khz out from the ssb
> signal.  This enables the receiver to frequency lock to the transmitted
> signal.  When a signal is received the signal is expanded and demodulated
> like an ssb signal with the pilot notched out.  When I lived in north Jersey
> in the 1990s there was a large acssb trunked system in the new York metro
> area.  I haven't caught any 220/222 activity here in my present location of
> southern Virginia.  I hope this helps.
>
>
> Dave Marthouse N2AAM
> [log in to unmask]
>
>
> ----- Original Message -----
> From: "Jeff Kenyon" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Saturday, October 23, 2004 5:58 PM
> Subject: 220 MHz use and modes used and possible encryption?
>
>
> > Hi everyone.  I was just doing a casual search of the 220-222 MHz range
> > here in my area, and I have a couple of trunked systems that are in my
> > area that are listed for  this band, and they are the MPT-1327 types of
> > systems, and when I have searched there before I have heard control
> > channels, and on one other occasion I have heard voice coms there, and
> > today I also heard these coms.  I first started to monitor in narrow band
> > FM which is the default for my scanner, and then tried to monitor in wide
> > band FM and AM with no luck.  It appears as though they are either using
> > SSB or some kind of analogue encryption.  I am not sure if there is any
> > conventional use or who else uses the 220-222 MHz band, but what I was
> > wondering is what have others heard in the 220-222 MHz range in your area?
> >
>