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|#185830 - Phone lines...|
Responding to: Mahmood Elnasser's previous message
I was investigating many methods of doing it, but since phone lines are available, I thought using the phone lines for both voice and DTMF signaling would be most suitable.
Yes, good idea, and way cheaper compared to optical fibers...
You could use transformers at both ends of phone line to provide galvanic isolation. But even opto coupling is possible, as Per mentioned. Then you could use the idle dc voltage on the phone line to power some little circuitry. But I guess using transformers will be much simpler and cheaper. Even ethernet is using tranformes, by the way.
But take care: In many countries the circuitry you connect to the phone line must electrically "look" like a standard telephone set, so that the phone line isn't loaded too much. So, you should have a look into the according standards...
Is it only one phone line you can access to transmit all the data and audio?
|long range RS-485||Mahmood Elnasser||02/10/12 01:51|
|Current loop?||Per Westermark||02/10/12 02:29|
|Repeaters?||Daniel Contarino||02/10/12 06:10|
|can you use repeaters?||Erik Malund||02/10/12 07:58|
|No||Mahmood Elnasser||02/10/12 14:10|
|Profibus people...||Kai Klaas||02/10/12 08:03|
|details||Mahmood Elnasser||02/10/12 14:24|
|just a note||Erik Malund||02/10/12 17:04|
|Phone lines...||Kai Klaas||02/10/12 17:06|
|phone lines||Mahmood Elnasser||02/10/12 23:06|
|Data collision||Kai Klaas||02/11/12 05:35|
|It just works at slow speeds||Oliver Sedlacek||02/14/12 05:03|