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I have a digital signal with the following characteristics:

High Level- +5V

Low Level- 0V

High Time- 1.3 uS

Low time- 2 Seconds

Both the high time and low times need to be have tight tolerances. I would also like to observe the jitter for both of them. What are the techniques available to probe the signal using an oscilloscope (I have a TDS 3034)?

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  • \$\begingroup\$ It was a typo. I meant both the high times and Low times. \$\endgroup\$ May 24 '12 at 7:30
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    \$\begingroup\$ Not sure how to do this with a scope. Do you have access to a frequency counter? \$\endgroup\$
    – Armandas
    May 24 '12 at 7:43
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    \$\begingroup\$ @VaibhavGarg, Tight tolerances is not clear. What is your tolerance on these? Do they both have 1pS tolerance, 1nS tolerance or as high as 1uS tolerance? I cant imagine those signals have the same tolerance. \$\endgroup\$
    – Kortuk
    May 24 '12 at 8:07
  • \$\begingroup\$ I'm not sure I appreciate the question - if this is just a pulsing signal, then there is only the jitter for the pulse - a low and a high themselves have no jitter, just the transition between the two. \$\endgroup\$ May 24 '12 at 8:35
  • \$\begingroup\$ @Cybergibbons - I don't see the problem. Jitter will result in deviation in the time from leading edge to leading edge, as well as deviation between leading edge and trailing edge. Apparently OP wants to measure against the previous edge. You'll get two numbers either way. \$\endgroup\$
    – stevenvh
    May 24 '12 at 8:42
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The pulse jitter shouldn't be a problem. Set your time base to 200ns (500ns if the jitter is high) and set display mode to infinite persistence. You should get all your pulses on top of each other, and be able to measure minimum and maximum pulse width.

The pause jitter is a different story, and I'm not sure the TDS3034 can handle a 2s trigger delay when your time base is for instance 1\$\mu\$s. This may call for a logic analyzer, which has a lot more triggering options. You may be able to set a trigger delay to 1 999 998\$\mu\$s. You won't see the exact waveform, i.e. voltage levels, but for measuring jitter this will probably not be important.

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TDS3034 is not a CRO (Cathode-Ray Oscilloscope), it's a digital scope. That means that you can trigger it for single shot sampling and analyse your waveform after.

What you need instead is knowing what are the tight tolerances, since you have very different high and low times, as you said, and you don't say what is the raise/fall time and how accurate (with numbers) you need it to be.

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