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significant digits in ADE assembler output expressions

an wx

hi all, I'm drawing spectrums in ADE Assembler when I encountered a problem. I want to calculate FFT with start/stop time at 1989.955ns/22469.955ns. In Calculator and in "Measurement"-"Spectrum" panel, I can enter the specific start/stop time and draw the spectrum as expected; however, as I send the expression to ADE, the stop time becomes 2.246996E-6, resulting in large spectrum leakage. If I set start and stop time to1989.950ns/22469.950ns so that no truncation occurs, the spectrum is normal. So it seems that the values are automatically rounded to 6 decimal places in ADE assembler output? How can I solve it?

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  • Andrew Beckett

    You can control the output precision either using Options->Output Formatting or per-output using this column:

    I'm slightly surprised though that if you have expressions used in other expressions as dependencies, then I wouldn't expect the truncation to have occurred (It's really just a display thing). Maybe it's become a fixed number at some point - it's not entirely clear what your setup looks like.

    Andrew

  • an wx
    in reply to Andrew Beckett

    Thanks for your reply, Andrew. Perhaps I haven't made myself clear enough. I mean that the values in the expression itself, instead of the values of the expressions' results, has been truncated. It seems that the 'Digits' column or Output Formatting only applies to the latter one.

    below is how I set up my expressions:

    First I plot spectrum using "Measurements"-"Spectrum" in ViVa. Then I select the spectrum waveform and send it to Calculator, where I got the expression "db20(dft((VT("/VXP") - VT("/VXN"))  1.989955e-06 22.469955u 1024 "Rectangular" 0 0 1))". The start and stop time is exactly what I want.

    Then, I select the spectrum waveform and send it to ADE. In ADE I found that the expression has become "db20(dft((VT("/VXP") - VT("/VXN")) 1.989955e-06 2.246996e-05 1024 "Rectangular" 0 0 1))". The stop time is now 2.246996e-05 (22.46996u instead of 22.469955u). I try to set stop time to 2.2469955e-05 manually, but it just doesn't work. I believe it isn't just a display thing, since as I re-evaluated the results in ADE, I do see spectrum leakage (which indicates that the FFT time window has changed).

    Something's wrong when I tried to upload screenshots :( I hope my descriptions are clear enough.

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  • an wx
    in reply to Andrew Beckett

    Thanks for your reply, Andrew. Perhaps I haven't made myself clear enough. I mean that the values in the expression itself, instead of the values of the expressions' results, has been truncated. It seems that the 'Digits' column or Output Formatting only applies to the latter one.

    below is how I set up my expressions:

    First I plot spectrum using "Measurements"-"Spectrum" in ViVa. Then I select the spectrum waveform and send it to Calculator, where I got the expression "db20(dft((VT("/VXP") - VT("/VXN"))  1.989955e-06 22.469955u 1024 "Rectangular" 0 0 1))". The start and stop time is exactly what I want.

    Then, I select the spectrum waveform and send it to ADE. In ADE I found that the expression has become "db20(dft((VT("/VXP") - VT("/VXN")) 1.989955e-06 2.246996e-05 1024 "Rectangular" 0 0 1))". The stop time is now 2.246996e-05 (22.46996u instead of 22.469955u). I try to set stop time to 2.2469955e-05 manually, but it just doesn't work. I believe it isn't just a display thing, since as I re-evaluated the results in ADE, I do see spectrum leakage (which indicates that the FFT time window has changed).

    Something's wrong when I tried to upload screenshots :( I hope my descriptions are clear enough.

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