[App_rpt] app_rpt setup and requirements.
hwstar at rodgers.sdcoxmail.com
Mon Oct 9 01:09:31 EDT 2006
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
> 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.
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.
> 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
> 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
> Eric - kg6kqt
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