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| Help me understand oscilloscope peak acquisition mode |
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| AJ528:
Hello all, I have a Siglent SDS 2000X Plus oscilloscope, and I have been trying to wrap my head around what Peak Acquisition mode does. The manual says, "The oscilloscope acquires the maximum and minimum values of the signal within the sample interval so that the peak (maximum – minimum) in the interval is obtained". While I understand the intent of peak acquisition mode, I'm confused how Siglent is implementing it. For example, let's say that during the sample interval there is a maximum value of +1 V and a minimum value of -1 V. The manual says peak = (maximum - minimum) = (1 - (-1)) = 2 V. Does that mean the oscilloscope plots a point at 2V? That doesn't make sense. I also tried answering my own question using a signal generator. I set the oscilloscope to capture 10kSa/s, then fed in a 1 Vpp sine wave. When measuring in normal acquisition mode, I saw what I expected to see (an approximate DC line since the sample rate and frequency matched). However, when I switched the oscilloscope to peak detect mode, the data points are frequently alternating between the min and max sine wave values, but not always. Sometimes it is 2 max points in a row, sometimes 2 min points. Can anyone explain what is happening here? How exactly are these points being selected during the sample interval? P.S. Please see the attached screen capture for an example of alternating min/max points during peak detect mode. Note that linear interpolation is being used to better highlight the data points. |
| tautech:
Please see Peak explanation on P79/80 in the User manual: https://int.siglent.com/u_file/download/22_05_18/SDS2000X%20Plus_UserManual_EN01D.pdf |
| AJ528:
Hi Tautech, Thanks for the reply. I have read the explanation in that part of the user manual. In fact, that's where I got the quote for what the user manual says. However, after reading that, I can't explain the data points I am seeing. Do you have any thoughts why the data points are appearing how they are? |
| Someone:
--- Quote from: AJ528 on December 04, 2023, 08:19:48 pm ---(an approximate DC line since the sample rate and frequency matched). However, when I switched the oscilloscope to peak detect mode, the data points are frequently alternating between the min and max sine wave values, but not always. --- End quote --- Try again, but with the frequency significantly larger and smaller than the sample rate. |
| tautech:
Zoom mode reduces sampling rates and user settings for mem depth reduce the # of sample points available for detailed analysis. Max mem depth and trigger settings can assist in getting accurate results. |
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