On Sat, 01 Oct 2005 19:48:00 GMT, Korbin Dallas
said in rec.radio.scanner:

On Fri, 30 Sep 2005 23:45:46 -0400, Al Klein wrote:

On Sat, 01 Oct 2005 01:43:09 GMT, Korbin Dallas
said in rec.radio.scanner:

On Fri, 30 Sep 2005 11:29:31 -0400, Al Klein wrote:
On Fri, 30 Sep 2005 13:35:23 GMT, "Jim Hackett"
said in rec.radio.scanner:

Digital?

Most of what we call "digital" is NFM or SNFM.

Actually "Digital" is C4FM.

And the modulation on the carrier is??? AM? PM?? FM??

What bandwidth is it?

There's a difference between the process of putting information on the
carrier and the format that information comes in. The OP was asking
about the physical layer, as specified by "AM/FM ..." etc..

The standard is APCO 25, which defines BW to be 6Khz and Modulation as
C4FM.

Again - what's the physical layer? Id the frequency of the carrier
changed? The amplitude? The phase? Some other characteristic of it?
The OP wasn't asking about the logical layer (which is where C4FM
sits), he was asking about the physical layer.