Well, I don't know if this will ever catch on as there are a handfull of
these systems here, and there is analogue encryption out there like those
used on baby room monitors and cordless phones that sound much like SSB
when heard, but is really a scrambling code.  I think that there is maybe
one or two MPT-1327 systems that are used for public safety in the states,
and I don't know about the mode the voice coms are carried out on, but
when I initially heard this earlier I thought either analogue encryption
or SSB.





On Sun, 24 Oct 2004 [log in to unmask] wrote:

> Message-Id: <20041024035433.XWAR22847.imf23aec.mail.bellsouth.net@[68.212.106.57]>
>
> Dave wrote:
>    >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.
> Yep, amplitude companded sideband.  IIRC there's a couple questions
> about it in the extra question pool.
> I'm surprised it hasn't caught on more than it has, the advantages of
> sideband without the tuning problems for the average JOe radio user
> who uses commercial type systems.
>
> 73 de nf5b
>
>
>
> Richard Webb
>
> Electric Spider Productions
> almost 50% of those at ground zero on 9/11/01 still have
> longterm health problems.  Almost half of those have no health insurance.
>