The build sequence (asterisk vs. gnuradio) is not important.
The folks who produce app_rpt have their own forked version of asterisk, which was the one
that I used.
Everything is coupled so loosely that there should not be much problem to mix & match
this stuff - although of course ymmv : )
The integration with asterisk is intended to be pretty extensible - currently the examples
all use app_rpt in its "dumb" mode. I'm sure that's a good starting
point but that a lot more could be done with some imagination. The choice of app_rpt was
mainly because that already provides almost the perfect set of semantics for what we want,
and was pretty mature in terms of capability. However the link to asterisk should be
viewed as a generalized "VOIP" bridge to OP25 not limited to repeaters in the
conventional sense... (think "ROIP")
There are some places where the existing asterisk app_rpt metaphor works less than
perfectly. The first is the app_rpt model in which audio that's been received over
the RX leg of a FDX link must first be demodulated and re-converted back to analog before
feeding through the app_rpt main path. This is Not Good due to the highly lossy IMBE
codec. A true digital P25 repeater would just regenerate the signal digitally before
retransmission. Unfortunately however this would cut app_rpt out of the picture
completely. A direct digital repeater is being looked at (with very slow progress).
Another problem is that DTMF tones (used heavily within asterisk and app_rpt) are verboten
in P25 (P25 has replacements in the form of packets that are defined in the protocol for
the purpose of sending dial digits).
At this stage in time I don't view the extra digital/analog/digital reconversion steps
as a problem. That would presuppose that the FDX links were working fully end to end.
Before that can happen we must first debug the individual legs, which is much easier to do
separately...
Looking forward to getting feedback from experimenters - it will help to guide the
development!
73
Max
--- In op25-dev(a)yahoogroups.com, "Doug Bade" <kd8b@...> wrote:
I guess another important question is if I am going to use asterisk, do I
want to start with an asterisk build first?? Or add it to this Debian box??
The build information does not really seems to mention where asterisk enters
in.. ( I have experience with Allstar Link and Asterisk PBX's for phone).
Doug
KD8B
From: op25-dev(a)yahoogroups.com [mailto:op25-dev@yahoogroups.com] On Behalf
Of Doug Bade
Sent: Monday, February 25, 2013 9:43 AM
To: op25-dev(a)yahoogroups.com
Subject: [op25-dev] Re: Full asterisk support?
I am going to throw my hat in too as a test site...
I have been copying the mail on this group for a while but had not really
caught the fact that the project was repeater capable. I have a station that
I can direct FM down pretty much to DC... ( Mastr III) ex-edacs station. It
has modulation ports I have been using for GMSK for D-Star to date using
sound FOBS. I am going to try to build all this but have a steep learning
curve as I have not even ever built the GNU radio parts.. So maybe I can
also be a test bed. I do have a P25 analyzer for setup. ( I maintain P25
systems (among other things)for a living ) I have some dedicated Atom rack
mount servers for building on..
When I built pre-re4quisits last night I had errors on SDCC and
SDCC-libraries on a fresh Debian build. Is the system particular about
versions of those? or just go get what I can find?? My Debian box was
building GNU radio stuff when I went to bed.. so I will get back to it
tonight..
I never really introduced myself here just been lurking... I am an LMR
systems engineer for a living and work on public safety P25 systems.. but am
an extra ham who likes to tinker.. P25 has always been a goal, as P25 cards
upgrades for my Mastr III station would run about $8000.00 if I did it the
Harris way :-)
Doug
KD8B
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