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09/17/10 14:33
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 		 #178579 - Squeezing DC through AC Channel
Responding to: ???'s previous message
RE:

It would be technically feasible to chop DC into two AC channels by chopping them up into two signals that are gated 180 degrees out of phase. As long as the resulting AC signals could be properly clamped to a reference voltage of some level so that software on the other side of the "sound card" could know what levels the converted samples actually represent then this may be a doable scheme. However I suspect the cost of the front end hardware to do even a reasonable job of it gets prohibitive. Probably beyond the FREE to $8.99 that such a scheme has to cost in order to be viable for this low end market.

There would also be issues involved with the chopping rate used, the aliasing that needs to be dealt with, and the fact that the audio channel conversion will distort the sample edges due to its own sample rate and antialiasing filters.

Michael Karas


List of 81 messages in thread
TopicAuthorDate
strange behaviour in serial communication            01/01/70 00:00      
   Slow VCC Decay            01/01/70 00:00      
      Get rid of the crappy R/C reset circuit            01/01/70 00:00      
   try this experiment...            01/01/70 00:00      
      totally irrelevant            01/01/70 00:00      
         thanks all            01/01/70 00:00      
            if you are running 5V ....            01/01/70 00:00      
               I agree            01/01/70 00:00      
         What's irrelevant is..            01/01/70 00:00      
            Not irrelevant to evaluate before buying            01/01/70 00:00      
            if this refer to my post ....            01/01/70 00:00      
               I am glad i started such a healthy discussion :)            01/01/70 00:00      
                  not start but restrart            01/01/70 00:00      
                     Will be more threads            01/01/70 00:00      
               to Gary Peek            01/01/70 00:00      
      I doubt that will help            01/01/70 00:00      
   bad news            01/01/70 00:00      
      time to show ...            01/01/70 00:00      
         Oh My Gosh            01/01/70 00:00      
            I do not know to which extent ...            01/01/70 00:00      
               A number of short forms are commonly accepted in formal text            01/01/70 00:00      
                  we are getting distracted here            01/01/70 00:00      
               What I would like to outlaw            01/01/70 00:00      
            SMS? I think not. Just in a hurry to prove...            01/01/70 00:00      
         here is the code again            01/01/70 00:00      
            that code could not possibly produce            01/01/70 00:00      
               but it is ...            01/01/70 00:00      
                  here are the screenshots from hyperterminal            01/01/70 00:00      
                     Still Seems Like...            01/01/70 00:00      
                     Could Also Be            01/01/70 00:00      
                     By the way...            01/01/70 00:00      
                        good advice and an addendum            01/01/70 00:00      
                           supervisor decoupling            01/01/70 00:00      
                              But things are quite slow!            01/01/70 00:00      
                                 yes cutting of DC fixed the issue            01/01/70 00:00      
                                    Are you sure?            01/01/70 00:00      
                                    Oh no it hasn't!            01/01/70 00:00      
                                       ok I agree , lets discuss            01/01/70 00:00      
                                          It depends on what your goals are            01/01/70 00:00      
                                          "DNA scope"            01/01/70 00:00      
                                          The Thing Is            01/01/70 00:00      
                                             Frequent examples            01/01/70 00:00      
   Scope time!            01/01/70 00:00      
      Would this sort of thing be at all helpful?            01/01/70 00:00      
         Quite possibly            01/01/70 00:00      
            I suspect they're all AC-coupled            01/01/70 00:00      
               AC Coupled -- No Good            01/01/70 00:00      
                  More than DC power decay...            01/01/70 00:00      
                  Isn't there some way of conditioning the input?            01/01/70 00:00      
                     No DC Bandwidth            01/01/70 00:00      
                        No argument there ... but ...            01/01/70 00:00      
                           Do you really think...            01/01/70 00:00      
                              Certainly, you're right ... however ...            01/01/70 00:00      
                                 Squeezing DC through AC Channel            01/01/70 00:00      
                                    and, for all practical purposes ...            01/01/70 00:00      
                                    How about this ... ???            01/01/70 00:00      
                                       Invert and add to subract the AC??            01/01/70 00:00      
                                          What about using other sampling hardware?            01/01/70 00:00      
                                             making a scope (sampling or not) is fairly simple            01/01/70 00:00      
                                                true enough ...            01/01/70 00:00      
                                                   USB modems really nifty            01/01/70 00:00      
                                                      Maybe the USB 'scopes are nifty ...            01/01/70 00:00      
                                                         USB 'scopes'            01/01/70 00:00      
                                                            for observing PSU behavior ...            01/01/70 00:00      
                                                               making a scope (sampling or not) is fairly simple            01/01/70 00:00      
                                                                  Well, I haven't tried it            01/01/70 00:00      
                                                                     another approach            01/01/70 00:00      
                                                                        Using hardware as built ... as much as possible            01/01/70 00:00      
                                                                           SiLabs C8051F34x            01/01/70 00:00      
                                                                              Which MCU is used doesn't matter ... yet            01/01/70 00:00      
                                                                                 But it does matter            01/01/70 00:00      
                                                                                    I agree, but ...            01/01/70 00:00      
                                                                        100MHz++ is nice but lots of areas are below 100kHz            01/01/70 00:00      
                                                                           While that works for some ...            01/01/70 00:00      
                                                                              Different tools good at different times            01/01/70 00:00      
                                                                                 no argument from me            01/01/70 00:00      
                                                                                    For one so insistent on answering the question as asked...            01/01/70 00:00      
                                                                                       This should have been a new thread, eh?            01/01/70 00:00      
                                                                                          Yes!            01/01/70 00:00      
                                                   too new, but            01/01/70 00:00      
                                                For crude display ...            01/01/70 00:00      

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