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Erik Malund
06/16/12 11:41
Read: 702 times
Mt Airy, Nc
USA


 
#187738 - and that's the crux
Responding to: Per Westermark's previous message
Note that they specify shortest trig pulse 24ns. So trying to trig on 1-20ns pulse lengths means you will test it outside the specified capabilities.
and that's the crux, hardware glitches are (most?) often shorter than 24ns.

I recall spending a month and a half together with a guy I consider extremely qualified chasing a hardware glitch that was shorter than the scope (of that day) could catch.

when considering scope specs, considering scoping normal events mkes no sense, why would you scope them if they were normal.

Mahmood,
just for kicks, why do you not make a "trigger expander" get a very fast retriggerable one shot, set it for ~33ns output and connect it to the external trig input and see if that works as a "trigger expander" you can make that while waiting for delivery and play with it and your current scope. If it works, it may be valuable for other people with scopes with subpar triggers.

Erik

List of 74 messages in thread
TopicAuthorDate
DSO for cheap!      Joseph Hebert      05/11/12 13:35      
   very good      Mahmood Elnasser      05/11/12 14:14      
      Limitations      Joseph Hebert      05/12/12 09:49      
         test results      Mahmood Elnasser      05/12/12 12:46      
            That's valuable information      Joseph Hebert      05/12/12 13:30      
         well, the fact is ..      Richard Erlacher      06/03/12 11:43      
            tektronix 475 comparison      Mahmood Elnasser      06/07/12 10:37      
               Really? Why?      Richard Erlacher      06/07/12 14:51      
               another double post ... sorry      Richard Erlacher      06/07/12 14:51      
   I think ...      Erik Malund      05/11/12 14:34      
      Application dependant      Mahmood Elnasser      05/12/12 05:55      
         Indeed      Andy Neil      05/12/12 09:10      
            It's still too low a bandwidth, wouldn't you say?      Richard Erlacher      06/03/12 11:50      
   just curious, Joe could you try      Erik Malund      05/11/12 14:36      
      Unusual with short pulses for hobbyist projects      Per Westermark      05/11/12 14:53      
         is the clock running?      Erik Malund      05/11/12 16:01      
      Sorry, but no I can't.      Joseph Hebert      05/11/12 16:42      
      10nSec Pulse      Mahmood Elnasser      05/12/12 12:59      
         "at random" means what exactly ?      Jim Granville      05/13/12 18:41      
            Answers      Mahmood Elnasser      05/14/12 07:41      
               more observations      Mahmood Elnasser      06/03/12 10:51      
                  It may not be the sample rate ...      Richard Erlacher      06/07/12 15:07      
                     digital vs analog      Mahmood Elnasser      06/08/12 15:34      
                        Don't get me wrong, here ...      Richard Erlacher      06/08/12 21:34      
                           poor mans's scope      Mahmood Elnasser      06/09/12 02:01      
                              Doesn't it depend on what THEY mean by bandwidth?      Richard Erlacher      06/09/12 20:58      
                                 20 nsec steps      Mahmood Elnasser      06/09/12 23:08      
                                    Well, one thing at a time ...      Richard Erlacher      06/10/12 11:43      
                                    Impulse Tests are better      Jim Granville      06/10/12 16:49      
                                       more capable scope      Mahmood Elnasser      06/11/12 14:03      
                                          I must have missed a step ...      Richard Erlacher      06/12/12 08:07      
                                             TEK475      Mahmood Elnasser      06/12/12 16:16      
                                                here's another alternative ...      Richard Erlacher      06/12/12 22:16      
                                                   DAC and pot in parallel?      Per Westermark      06/13/12 01:07      
                                                      Logically, not physically      Richard Erlacher      06/13/12 07:57      
                                                   new theory      Mahmood Elnasser      06/14/12 00:57      
   3MHz is rather poor Bandwidth ?      Jim Granville      05/11/12 16:51      
      ordinary      Erik Malund      05/11/12 17:20      
         Ther are many params needed      Jim Granville      05/11/12 18:21      
   "only" $200 ?      Andy Neil      05/11/12 23:59      
      Low cost oscilloscopes      Andy Neil      05/12/12 09:18      
         291 > 2*($199)      Joseph Hebert      05/12/12 09:45      
            It doesn't always work that way      Andy Neil      05/12/12 10:48      
               Once upon a time ...      Joseph Hebert      05/12/12 13:28      
   SDS8202      Mahmood Elnasser      06/14/12 13:58      
      Read all the "fine print' first ... and ask any questions      Richard Erlacher      06/14/12 20:31      
         bought it      Mahmood Elnasser      06/16/12 03:07      
            Please let us know how this works out for you      Richard Erlacher      06/16/12 04:19      
               datasheet      Mahmood Elnasser      06/16/12 05:26      
                  2mV/div - but min trig level?      Per Westermark      06/16/12 07:01      
                     Tests      Mahmood Elnasser      06/16/12 09:55      
                        24ns      Per Westermark      06/16/12 11:09      
                           and that's the crux      Erik Malund      06/16/12 11:41      
                              FPGA pulse Expander (edited)      Mahmood Elnasser      06/16/12 12:06      
                                 some love the mother, some love the daughter        Erik Malund      06/16/12 12:13      
                                 Here's omne fairly simple thing ...      Richard Erlacher      06/16/12 15:22      
                                 self calibtrate?      Jim Granville      06/16/12 20:42      
                                    interesting      Mahmood Elnasser      06/16/12 23:01      
                                       yes      Jim Granville      06/16/12 23:15      
                                          glurk      Jez Smith      06/17/12 13:33      
                                             DCMs      Mahmood Elnasser      06/17/12 14:49      
                                                Well....      Jez Smith      06/17/12 15:48      
                                                   I don't know where you're going with this ...      Richard Erlacher      06/17/12 21:25      
                                             xxxxx      Mahmood Elnasser      06/20/12 12:53      
                           333ps      Mahmood Elnasser      06/18/12 00:59      
      SDS9302      Mahmood Elnasser      07/05/12 10:32      
         So, how are you exercising this new 'scope?      Richard Erlacher      07/05/12 10:53      
            so far so good      Mahmood Elnasser      07/08/12 09:45      
               So far so good ...      Richard Erlacher      07/08/12 10:49      
                  rise time      Mahmood Elnasser      08/15/12 13:28      
                     The rise time indicates that high frequencies gets dampened      Per Westermark      08/15/12 16:26      
                     What does "bandwidth" mean?      Richard Erlacher      08/15/12 17:45      
                        good test      Mahmood Elnasser      08/30/12 15:09      
                           Perhaps you should repeat the test ...       Richard Erlacher      08/30/12 23:08      

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