Hi Richard,

Acssb would be interesting to experiment with on the amateur bands.  I think
it hasn't caught on do to the fact that digital communications techniques
such as apco25 and such are the next communications frontier.


Dave



----- Original Message -----
From: <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, October 24, 2004 5:54 AM
Subject: Re: 220 MHz use and modes used and possible encryption?


> 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.
>
>