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???
12/27/07 14:23
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 		 #148795 - Driver/interface
Responding to: ???'s previous message
AP,
If you use a modem chip then you can use the audio class drivers if you like. Nothing outside the 8K bandwidth will be created by the modem chipset. I would however stay with the telephone mentality and forget active balanced circuits.
Check out the link below. It has several circuits based on a 'talk battery' and a few opamps for the interface. If the modem chipset can be made to pickup without dial tone etc, then this is a very valid solution up to 56K and bi-directional on a single pair. I also like the 600Ohm transformers for their isolation and balance. You can even increase the drive voltage as needed by simply changing some resistor values.

http://www.tkk.fi/Misc/Elec...l#audioint

BTW: 48vdc is very easy to get these days with the low cost DC-DC converters.

List of 56 messages in thread
TopicAuthorDate
Line driver IC            01/01/70 00:00      
   Telephone lines?            01/01/70 00:00      
   Slower analog solution..            01/01/70 00:00      
   That's a job for a transfomer!            01/01/70 00:00      
      line driver            01/01/70 00:00      
         Missing the point            01/01/70 00:00      
            Eh?? What is            01/01/70 00:00      
               Modem?            01/01/70 00:00      
                  Think Telco even if it's not            01/01/70 00:00      
               Have you read the datasheet?            01/01/70 00:00      
                  Not the modem speed            01/01/70 00:00      
                  What datasheet??????            01/01/70 00:00      
                     That is the datasheet            01/01/70 00:00      
                        I mentioned the chips and you say I havnt            01/01/70 00:00      
               No, you don't            01/01/70 00:00      
         Xformer only            01/01/70 00:00      
            at this low data rate (9600 bps) he could use AMI            01/01/70 00:00      
               AMI protocol            01/01/70 00:00      
                  who said anything about protocol?            01/01/70 00:00      
                     Difficult and with few software options            01/01/70 00:00      
                        Nobody said anything about a protocol            01/01/70 00:00      
                           Getting ahead of the questions            01/01/70 00:00      
                              fact is ... we don't have the information ...            01/01/70 00:00      
                                 Spare wire is already there . We do not            01/01/70 00:00      
                              Getting ahead of the questions            01/01/70 00:00      
                                 What type of wire and what environment?            01/01/70 00:00      
                                 please stop this mistreatment of a word            01/01/70 00:00      
                                    A Protocol is a set of guidelines or rules.            01/01/70 00:00      
                                    Apologies , I meant CODEC nor protocols            01/01/70 00:00      
         I am not sure...            01/01/70 00:00      
   27 or more solutions exist ...            01/01/70 00:00      
      ~9600bps            01/01/70 00:00      
         9600 is tough at that distance, so            01/01/70 00:00      
            Tough?            01/01/70 00:00      
               Not Tough? but costly.            01/01/70 00:00      
                  Still missing the point            01/01/70 00:00      
      He did specify the data rate            01/01/70 00:00      
         Where to apply modulation schemes when            01/01/70 00:00      
            Oh yes you have!            01/01/70 00:00      
            Driver/interface            01/01/70 00:00      
   no            01/01/70 00:00      
   Maxim Preemph RS-422 driver            01/01/70 00:00      
      FEET            01/01/70 00:00      
         speed and distance still apply            01/01/70 00:00      
            a pretty fancy rf link would fit the cable budget            01/01/70 00:00      
               Reverse engineer these            01/01/70 00:00      
                  Reverse engineer these            01/01/70 00:00      
                     buy one and find out            01/01/70 00:00      
                     Seems simple enough!            01/01/70 00:00      
                  Why not            01/01/70 00:00      
                     No black (box) magic methinks            01/01/70 00:00      
                        an other blackbox            01/01/70 00:00      
                           current loop vs balanced signal lines            01/01/70 00:00      
                              Have you ever heard of the teletype?            01/01/70 00:00      
                                 Bell system teletypes            01/01/70 00:00      
                              10...15years ago            01/01/70 00:00      

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