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Oscilloscope to measure Non-Periodic Random Signals...

  1. Jul 31, 2015 #1
    Hello Forum,

    I know a little bit about how the oscilloscope works: an electron beam hits the scope screen and traces the waveform. Once the beam reaches the right side of the screen it zaps back to start tracing again. Is it possible that while the beam returns to the lefthand side of the screen the portion of the signal occurring during that time will not represented>

    If the input signal is a sinusoid (periodic), it is important to set the oscilloscope trigger so that the sinusoid is well traced and the beam always starts from the same point. Otherwise we would see many overlapping sinusoids on the screen. The options seem to be auto trigger and slope trigger.

    Question: if the input signal is random, non predictable, non periodic, what type of trigger setting do we need to use to correctly capture and trace the signal on the screen? Could we miss part of the random signaI if the beam starts tracing always and only from same point on the lefthand side of the screen? The random signal may start from different points at different times at the left side of the screen...

  2. jcsd
  3. Jul 31, 2015 #2


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    You use a digital storage oscilloscope to capture a long sequence of signal data then use search or trigger functions to find the random signal.

    Modern scopes are designed to handle this easily.
  4. Jul 31, 2015 #3


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    Staff: Mentor

    As nsaspook says, a digital oscilloscope does not have the limitations you are mentioning. What you have described is the older analog oscilloscope technology.
  5. Jul 31, 2015 #4


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    The King of analog scopes the Tek 2465+ (that I have and love) series had some primitive add-on probes to help with random event triggers but DSO models are light-years ahead of what they could measure.
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