see below: On 10/8/06, Steve Rodgers <hwstar@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 _______________________________________________ App_rpt mailing list App_rpt@lists.illiana.net http://lists.illiana.net/mailman/listinfo/app_rpt