[Namaste-dev] Re: Interoperability through APCO-25

Michelle w5nyv at yahoo.com
Thu May 22 12:13:53 PDT 2008

I'll try to add to the very good discussion here, with some thoughts on the endeavor.
As originally envisioned, as discussed in February in Florida, and as presented at Dayton, the intended users of the ground station include both amateur radio operators and emergency communications operators. 
Supporting emergency communications requires a response to the rise of the APCO-25 standard. At a very minimum, we have to be able to intelligently articulate why it's not in our interests to provide interoperability in a particular way. My feeling is that it is very much in our interests, and I'm interested to prove this feeling one way or another.
Navigating policy and politics is part of the engineering challenge to Namaste. There are lots of communications projects that involve much much less in terms of the policy and politics issues. Namaste, as chartered by Bob McGwier, is not necessarily one of those, since we're playing in an area that is dominated by policy and politics issues. However, there are large parts of the project that are largely free of the sorts of issues that you are talking about, and offer a more purely technical challenge.
In other words, there are constraints introduced on this module due to the national and political nature of this endeavor. They are not insurmountable, but they may not be simple to comply with. 
Are you interested in taking on the challenge of approaching the question of APCO-25 interoperability? I'd like to find at least 5 people that are interested and willing to develop requirements that will enable us to design (from requirements to validation) a terrestrial interface to APCO-25 devices.
We will do whatever it takes to achieve this, if it is feasible. So far, I see nothing that would contraindicate our ability to interoperate. Instead, I see legitimate realizations of the challenges in this area. 
There are costs, and there are hoops. The vocoder issue is publicized well enough that I know about it, and I am sure there are clever ways to approach it. Standards bodies quite often charge money for standards, and we can afford to buy the standard. We can accomodate standards that are not open for an optional module for a microwave-band satellite ground station, if the case is compelling enough.
In talking with emergency communications workers and representatives, I'm getting the impression that it is. 
With optimism and flexibility, I think the scope of work I'm talking about is achievable, desirable enough from an interoperability viewpoint, well-defined enough to where work can begin, and rewarding enough technically to justify the time it will take to achieve the end result.
Would you like to be involved in being responsible for this part of the project? I'd like that a lot, and I hope you'll consider it.
 -Michelle W5NYV

----- Original Message ----
From: Eric Blossom <eb at comsec.com>
To: Michelle <w5nyv at yahoo.com>
Cc: namaste-dev <namaste-dev at amsat.org>; Tom Rondeau <trondeau at vt.edu>
Sent: Thursday, May 22, 2008 11:44:07 AM
Subject: Re: [Namaste-dev] Interoperability through APCO-25

On Thu, May 22, 2008 at 10:02:31AM -0700, Michelle wrote:
> Emergency communications interoperability through an APCO-25 terrestrial interface has been proposed.
> This would increase emergency communications usability and increase opportunities for funding.
> Here is a short introductory article on APCO-25. 
> http://en.wikipedia.org/wiki/Project_25
> Here is an industry article about APCO-25.
> http://www.info4u.us/APCO25/
> Here is the project home page.
> http://www.apco911.org/frequency/project25/index.html

> There is an information page of interest at the same site as the home page.

> http://www.apco911.org/frequency/project25/information.html

> People "in the know" refer to the standard as P25.1, meaning APCO
> project 25 phase 1, which is the current phase. Phase 2 and up
> are in development.  What I'd like to do is explore the idea of
> using a cognitive radio module to handle the interoperability. This
> would rely upon Tom Rondeau's work, as explained in his
> dissertation. What I need are people that are interested in
> taking on the responsibility of supporting this terrestrial module
> for Namaste. This means learning the standards well enough to assist
> in writing and reviewing requirements, establishing the feasibility
> of using cognitive radio technology to bridge between our IP layer
> and external APCO-25 waveforms, and then supporting the design
> effort.

I understand the desire for funding, however...

After talking with Vanu Bose (www.vanu.com) about various public safety
interoperability offers they had made, he indicated that the issue is
not technical, but is one of policy and politics.  It's about
maintaining a chain of command.  The fire chief doesn't want other
people talking to her crew, and doesn't want them listening to anybody
else either.

Is being "open" and "free" a design objective / requirement?

Last time I checked, the P25 specs weren't open and cost about
$2.5k unless you were law enforcement or government.

How would you handle the proprietary vocoder?
How about any patents relating to P25?

Of the public safety systems installed, what percentage of them are
using P25.* vs EDACS vs anything else?  Of the current P25
installations, how many of those are running Motorola proprietary

Summary: if you're willing to sacrifice open and free as a
requirement, then yes, it's possible to create a gateway to/from P25.
I'm not sure how much cognition is involved in any of this.  Other
issues include mapping to/from talk groups, authentication,
encryption, and arbitration of big pipe into little pipe.

Eric K7GNU

More information about the Namaste-dev mailing list