[App_rpt] app_rpt setup and requirements.

Eric Fort eric.fort at gmail.com
Mon Oct 9 02:06:01 EDT 2006


see below:

On 10/8/06, Steve Rodgers <hwstar at rodgers.sdcoxmail.com> wrote:
>
> Eric,
>
> See below for the answers.
>
>
> On Sunday 08 October 2006 19:11, Eric Fort wrote:
> > Hopefully those on the list can answer a few questions about getting
> > app_rpt setup and what is really required.
> >
> > 1.  why is the arib needed and what exactly does it do?
>
> The main task of the ARIB is to separate the audio from the signaling.
> FXS connections carry audio (AC) and signalling (DC) on the same twisted
> pair.
> The signalling and the audio need to be separated when interfacing to a
> radio.
>
> >
> > 2.  Why do I need 2 fxs ports for full duplex operation?  my phone is
> full
> > duplex when plugged into the same port why can't the audio for the radio
> > be?
>
> > Come to think of it I can buy a little phone with a headset jack for
> > next to nothing and have seperate tx (mike) and rx (speaker)
> audio.  this
> > just takes a 2 to 4 wire hybrid common to most phones.  why do I need
> the
> > arib at all?
> >
> > 3.  Why do I need the arib at all?
>
>
> For full-duplex repeater operation 2 FXS ports are an absolute
> requirement. To
> see why, keep reading.  If you are not running a repeater, onty one FXS
> port
> is needed, and a two wire connection can be used.
>
> We prefer to set up repeaters instead of half-duplex configurations like
> Echolink or IRLP. We feel the full duplex repeater configuration gives us
> more control as we can issue commands while the transmitter is still
> transmitting, and we don't have to wait for a transmitter to unkey before
> starting a new transmission.


agreed, the cactus intertie which I use much of the time is full duplex and
it offers many advantages.

Why the two FXS port requirement for full duplex audio? For full duplex
> audio
> (simultaneous receive and transmit) as used with repeaters, no receive
> audio
> can be allowed to couple into the transmit audio, without going through
> audio processing (muting, mixing, etc) first. The hybrid transformers used
> in
> phones don't have to be perfect full duplex devices. What I mean by
> perfect
> full duplex device, is that no receive audio is discernable in the
> transmit
> audio. Phones are not perfect full duplex devices, in fact, some receive
> audio is purposely introduced in the transmit audio to generate a
> sidetone.
> Even the hybrid transformer  is still not going to do an acceptable job of
> rejecting the receive audio on the transmit port, hence the need for a
> 4-wire
> connection back to Asterisk using 2FXS ports.


thanks for the explaination.  too bad there are not 4 wire modules for the
DIGIUM cards.  what about using an E&M interface/port for radio interfacing
(6 wire)?

>
> > 4.  is the rbi-1 really needed?  what function does it serve?  I've seen
> > mention of using an ft-897 directly without it.  How is this done?  why
> hf
> > only for the 897 when the 897 covers hf, 6m, 2m, and 440?
>
> The RBI-1 is only required it you want to change the frequency of your
> radio
> remotely, and you have the Kenwood mobile radios which are compatible with
> it.


does app_rpt speak the cat protocol to a serial port?  can an ft897 be used
in a frequency agile way, just by plugging it in (to the arib board?  if not
what would it take to impliment this?  where can I find docs about how this
setup was made to work for the demo.

>
> > 5.  what about interfacing other radios used for repeaters such as
> micor,
> > maxtrack, etc.
>
> We do it all the time. My repeaters are all Motorola Mitrek, or GE Custom
> MVP.
> Other guys use Maxtracs, and Desktracs or other synthesized commerial land
> mobile radios.



are docs/diagrams available to  show how this is done?


>  Thanks,
>
>  Eric - kg6kqt
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