[Namaste-dev] Re: Thoughts on ACP Interoperability

Timothy J. Salo salo at saloits.com
Sun Jul 13 12:52:04 PDT 2008


Rick Hambly (W2GPS) wrote:
> Thank you for your input. I strongly agree that any external interface with
> the ground station should be IP based. That opens up a number of Ham-centric
> and emergency communications application interfaces that can easily be built
> on top of IP. ...

Perhaps more importantly, it enables the ACP to interconnect
existing devices and systems that use IP (which is pretty
much every networked device in the known universe).  This
includes existing P25 equipment.

> Could we put applications like a P25/IP interface in our PC or laptop,
> thereby separating this applications issue from the immediate need to get an
> affordable ACP ground station built soon? I don't really know enough about
> P25 or its implications (technical, legal) to know.

I strongly recommend that we simply go buy (rather than
build) a P25/IP device.  I don't see any reason for radio
amateurs, and particularly satellite amateurs, to build
yet another P25/IP device.  Our energy should be focused
on making the the ACP system work well and interface
gracefully with existing IP devices and networks.  (These
are probably a bit trickier than they first appear...)

For example, E.F. Johnson sells P25 devices that:

o Interconnect P25 repeaters over an IP network

o Interconnect P25 repeaters with analog voice systems
   (over an IP network, I think)

o Interconnect P25 repeaters with voice-over-IP systems

The ACP should provide IP connectivity that is
compatible with these existing P25 devices.

While this site doesn't provide any technical detail,
it does hint at some of the capabilities of existing
P25/IP systems:

   <http://www.efjohnson.com/products/IP25.asp>

In short, I suggest that the ACP project:

o Provide IP connectivity between IP devices and networks

o Explain to the public safety community how this IP
   connectivity that we can provide is useful in their
   existing communication systems and organizational
   structures

Actually, my highest-priority recommendation is that this
e-mail list be moved somewhere that has latencies and jitter
measured in minutes rather than hours (well, maybe days -- I
haven't yet received all of the mail, so I don't really know
the maximum latency...)

-tjs



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