Assume you are given a chain of microwave radios with a 4-wire audio circuit going through for "order wire". This is essentially a party line through all the sites. DTMF signalling is normally used to control things. I'd like to install a telephone interconnect at one end so that one can dial out into the PSTN, or receive incoming calls. The concept would be similar to any phone patch on a conventional repeater. Zetron and others make these interconnect panels complete with 4-wire 600 ohm full duplex audio interfaces for the radio side. However, in a order wire application, there is no Carrier Operated Relay. The interconnect would have to accept DTMF commands and go on or off-hook solely by DTMF or timer functions. The call time out is a standard feature, but DTMF time-out (like on a PBX, wait 5 seconds and accept in no more digits follow) is not. Zetron technical support tells me that without COR, their interconnect won't function correctly. Other this this snag, one of their patches would be ideal.
Does anyone have any experience with this sort of thing or could make a recommendation? Or is Zetron just not understanding the application?
Thanks in advance,
RF Dude
Telephone Interconnect for Order Wire
Moderator: Queue Moderator
Orderwire telephone line interface
[quote="Al"]Are you sure there's no E&M lead signalling available on the microwave orderwire equipment? If there is, you would interface your E&M signalling directly with the Zetron or whatever interconnect you're using to tell the Zetron what action to perform, i.e. on-hook, off hook, etc.[/quote]
We had a telephone line interfaced with our orderwire on the microwave. Sounds like your trying to go about it the hard way. Only thing different was we could only originate a call.
It was a simple DTMF decoder and some line amps. You have to have a 4 wire to 2 wire hybrid to make it work. Set up the decoder to say a 4 digit number to obtain a line connection and then dial the phone number you want. You could get fancy and put a vox sense circuit and use it to run a resetable timer to disconnect the phone line with no audio for say 5 minutes. Or you could send another DTMF code to release the phone line.
Jim
We had a telephone line interfaced with our orderwire on the microwave. Sounds like your trying to go about it the hard way. Only thing different was we could only originate a call.
It was a simple DTMF decoder and some line amps. You have to have a 4 wire to 2 wire hybrid to make it work. Set up the decoder to say a 4 digit number to obtain a line connection and then dial the phone number you want. You could get fancy and put a vox sense circuit and use it to run a resetable timer to disconnect the phone line with no audio for say 5 minutes. Or you could send another DTMF code to release the phone line.
Jim
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psapengineer
- Posts: 175
- Joined: Thu Oct 07, 2004 10:00 am
Zetron 72
Hi,
If you calling Zetron asking for an interconnect you're likely getting the wrong product group; the one that sells interconnects.
You may be looking for their Model 72. It extends a telephone line over a full duplex link. I'm not shure if your orderwire has side tone or how it will work in you particular system; you will need to check it out first. But, I'm thinking that this might do what you're asking for:
http://www.zetron.com/pages/english/products/m72.html
Good Luck, Bob
If you calling Zetron asking for an interconnect you're likely getting the wrong product group; the one that sells interconnects.
You may be looking for their Model 72. It extends a telephone line over a full duplex link. I'm not shure if your orderwire has side tone or how it will work in you particular system; you will need to check it out first. But, I'm thinking that this might do what you're asking for:
http://www.zetron.com/pages/english/products/m72.html
Good Luck, Bob