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???
06/17/12 02:42
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 		 #187745 - self calibtrate?
Responding to: ???'s previous message
Mahmood Elnasser said:
My only concern is to be able to measure width of small pulses so that I can use for my experimentation.


This will always bump into pin skew issues, but a common method with FPGA is to use their Delay elements, or make your own, and calibrate.

A pair of string of gates, with many capture FF's that you alternate between capture and calibrate will get you under 1ns in LSB resolution.

eg suppose a gate-delay of 200ps, and a 200MHz clock, then you need a string of over 25 to capture a whole cycle.

List of 74 messages in thread
TopicAuthorDate
DSO for cheap!            01/01/70 00:00      
   very good            01/01/70 00:00      
      Limitations            01/01/70 00:00      
         test results            01/01/70 00:00      
            That's valuable information            01/01/70 00:00      
         well, the fact is ..            01/01/70 00:00      
            tektronix 475 comparison            01/01/70 00:00      
               Really? Why?            01/01/70 00:00      
               another double post ... sorry            01/01/70 00:00      
   I think ...            01/01/70 00:00      
      Application dependant            01/01/70 00:00      
         Indeed            01/01/70 00:00      
            It's still too low a bandwidth, wouldn't you say?            01/01/70 00:00      
   just curious, Joe could you try            01/01/70 00:00      
      Unusual with short pulses for hobbyist projects            01/01/70 00:00      
         is the clock running?            01/01/70 00:00      
      Sorry, but no I can't.            01/01/70 00:00      
      10nSec Pulse            01/01/70 00:00      
         "at random" means what exactly ?            01/01/70 00:00      
            Answers            01/01/70 00:00      
               more observations            01/01/70 00:00      
                  It may not be the sample rate ...            01/01/70 00:00      
                     digital vs analog            01/01/70 00:00      
                        Don't get me wrong, here ...            01/01/70 00:00      
                           poor mans's scope            01/01/70 00:00      
                              Doesn't it depend on what THEY mean by bandwidth?            01/01/70 00:00      
                                 20 nsec steps            01/01/70 00:00      
                                    Well, one thing at a time ...            01/01/70 00:00      
                                    Impulse Tests are better            01/01/70 00:00      
                                       more capable scope            01/01/70 00:00      
                                          I must have missed a step ...            01/01/70 00:00      
                                             TEK475            01/01/70 00:00      
                                                here's another alternative ...            01/01/70 00:00      
                                                   DAC and pot in parallel?            01/01/70 00:00      
                                                      Logically, not physically            01/01/70 00:00      
                                                   new theory            01/01/70 00:00      
   3MHz is rather poor Bandwidth ?            01/01/70 00:00      
      ordinary            01/01/70 00:00      
         Ther are many params needed            01/01/70 00:00      
   "only" $200 ?            01/01/70 00:00      
      Low cost oscilloscopes            01/01/70 00:00      
         £291 > 2*($199)            01/01/70 00:00      
            It doesn't always work that way            01/01/70 00:00      
               Once upon a time ...            01/01/70 00:00      
   SDS8202            01/01/70 00:00      
      Read all the "fine print' first ... and ask any questions            01/01/70 00:00      
         bought it            01/01/70 00:00      
            Please let us know how this works out for you            01/01/70 00:00      
               datasheet            01/01/70 00:00      
                  2mV/div - but min trig level?            01/01/70 00:00      
                     Tests            01/01/70 00:00      
                        24ns            01/01/70 00:00      
                           and that's the crux            01/01/70 00:00      
                              FPGA pulse Expander (edited)            01/01/70 00:00      
                                 some love the mother, some love the daughter            01/01/70 00:00      
                                 Here's omne fairly simple thing ...            01/01/70 00:00      
                                 self calibtrate?            01/01/70 00:00      
                                    interesting            01/01/70 00:00      
                                       yes            01/01/70 00:00      
                                          glurk            01/01/70 00:00      
                                             DCMs            01/01/70 00:00      
                                                Well....            01/01/70 00:00      
                                                   I don't know where you're going with this ...            01/01/70 00:00      
                                             xxxxx            01/01/70 00:00      
                           333ps            01/01/70 00:00      
      SDS9302            01/01/70 00:00      
         So, how are you exercising this new 'scope?            01/01/70 00:00      
            so far so good            01/01/70 00:00      
               So far so good ...            01/01/70 00:00      
                  rise time            01/01/70 00:00      
                     The rise time indicates that high frequencies gets dampened            01/01/70 00:00      
                     What does "bandwidth" mean?            01/01/70 00:00      
                        good test            01/01/70 00:00      
                           Perhaps you should repeat the test ...             01/01/70 00:00      

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