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

Michelle w5nyv at yahoo.com
Fri Jun 13 10:30:07 PDT 2008

A requirements analysis of the interoperability module is in progress. Drafts will be released as soon as they're done. Joanne Maenpaa is the lead on this part of the project, and I support her plan and basic approach. I'm very interested in the eventual outcome of her work, since it gets right to the heart of one of the two intended audiences for our project - emergency communications operators.  
After requirements analysis comes design and proposals for implementation. We're not there yet, and depending on the use case study, regulatory issues, and legal issues, we may decide not to pursue particular types of interoperability because they make no sense for us to do. 
Terrestrial demonstrations with a satellite simulator are something we intend to do. A terrestrial demonstration for both our intended audiences will happen regardless of an optional APCO-25 module. It's an option we're considering supporting. It doesn't hold up the terrestrial demonstration. 
The date of the terrestrial demonstration has not been scheduled. I expect to discuss this and many other subjects at the July meeting.

 -Michelle W5NYV

----- Original Message ----
From: Bob McGwier <rwmcgwier at gmail.com>
To: namaste-dev at amsat.org
Sent: Thursday, June 12, 2008 10:08:54 PM
Subject: [Namaste-dev] Interoperability through APCO-25

With all of the many users of APCO-25 in the area of emergency 
communications, this would be the ideal theoretical candidate in my opinion.

However, until and unless we are allowed to protect these 
communications, it seems unlikely this will work or be used. Next, I am 
unsure we are legally allowed to interconnect users of these services 
directly which I believe is the implication.

We can pass the audio under the control of a control operator as if 
doing a phone patch but the passage of the control channels, digital 
data, etc. Next, phase 2 uses AMBE to reduce the data rate to 4800 bps. 
We can easily use the "USB dongles" to do the AMBE but I only ask the 
question is this level of complexity necessary for us to do the basic 
experiments? I cannot see how we will convince the FCC to allow us to 
put a radio of our own manufacture on the P25 bands. We will certainly 
see lots of push back from manufacturers. I am willing to be convinced 
but this seems like a big hurdle.

Worried about this in NJ,

ARRL SDR Working Group Chair, AMSAT VP Engineering.
Member: ARRL, AMSAT, AMSAT-DL, TAPR, Packrats,
“Trample the slow ....  Hurdle the dead"

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