There are different modes used with trunking such as digital and analogue
and encryption.  Do not confuse digital with encryption.  Here in the U.S.
a lot of agencies are going with Project 25 which is a digital standard
that was developed by Motorola.  This is the Common Air Interface, CAI,
but Motorola also has other forms of digital.  Then, EDACS trunked systems
may also use AEGIS which is another form of digital.  As far as the CAI
goes comms are clear, and you don't have any static t all, but someotmes
on the fringes of coverage regions it will become warbley.  There sill be
an APCO-25 capabee scanner at the end of the year which is what I posted
about yesterday, and part of today.





On Fri, 16 Aug 2002, John Farina wrote:

> Hello,
>
> For those who are wondering what trunking is, it is a system where by the
> frequency of a public service agency may shift.  In other words, the agency
> has a group of frequencies within the 800 mhz band and they use them all, or
> portions of them.  what this does to conventional scanners is that they will
> never get both sides of the conversation because it begins on one frequency
> in the group and ends on another.
>
> There is a control channel keeping track of this for the system.  A trunking
> scanner is capable of following the movements by tuning in to the control
> channel.
>
> This is probably not the best explanation for this but I think folks will
> get the idea.  It would be similar to having a qso on the band while moving
> your vfo up and down, the receiving station would need to move in the exact
> sequence or they would never find you again.
>
> Hope that helps, if anyone has a more thorough explanation go for it please.
>
> 73
>
> de w2qcy
>