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I bought a used SDR33 Expert 4MB. When I tried using it for Topographic survey, backsight residual report is always to the tune of more than 5 minutes. I am not comfortable with it. Did I miss something?

Thank you guys..


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  • Arnel,

    I reviewed the .sdr file and I see that your EDM distances are very good between points, however, I also noticed how far out of tolerance the Vertical Error is.  I noticed that you measured the height of your instrument above the point being occupied, but I don't see a rod height or a value for the height of your backsight tripod.  Are you measuring the height of your instrument above the point you are occupying and also measuring the height of the prism that you are using for a backsight, then entering this info into the SDR at each Turning Point?

  • Arnel,

    I just left a reply to your post about the raw file.  I think I can help with interpretation.  As for the backsight being "off" by 5 minutes, we need to know if the problem lies within the collector, within the instrument being used, within what may be a compatability issue, what may be a matter of changing a few settings on one or the other, or whether it is just a simple procedural issue.  More info please.  I'm here to help.

    -Scott D. Warner, R.L.S.

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