Topic outline

  • Adjustment of GPS Surveys

    Credits: 4 PDH

    PDH Course Description:

    This course describes some of the methods used to perform GPS survey adjustments and provides guidance in evaluating the adequacy and accuracy of the adjustment results. Differential carrier phase GPS survey observations are adjusted no differently than conventional, terrestrial EDM surveys. Each three-dimensional GPS baseline vector is treated as a separate observation and adjusted as part of a trilateration network. A variety of techniques may be used to adjust the observed GPS baselines to fit existing control. Since GPS
    survey networks often contain redundant observations, they are usually adjusted by some type of rigorous least-squares minimization technique.

    While the underlying technique may be similar for most GPS survey adjustment software packages, the user interface, process flow, and default settings will vary from vendor to vendor. The detailed instruction manuals provided by the vendor, along with any sample adjustment projects, should be carefully reviewed and consulted for proper use. Additional technical training courses may be offered by the vendor as well.

    Topics:

    • Adjustment Considerations
    • GPS Error Measurement Statistics
    • Survey Adjustments and Accuracy
    • Free or Minimally Constrained Adjustments
    • Fully Constrained Adjustments
    • Partially Constrained Adjustments
    • Rigorous Least-Squares Adjustments of GPS Surveys
    • Network Adjustment Software
    • Network Adjustment Criteria
    • Baseline Weights-Covariance Matrix
    • Adjustment Output Statistics
    • Minimally Constrained Adjustment Considerations
    • Relative Baseline Accuracy Estimates
    • Normalized or Standardized Residuals
    • Positional Accuracy Statistics and Error Ellipses
    • Examples of Network Adjustments

    To take this course:

    1.) Enroll in Course: Click below to enroll:
    (must be logged into your user account)


    2.) Study: Once enrolled, click below to begin the course:

    Download the Study Guide

    3.) Test: Once you've thoroughly read the course materials, please click below to take the final examination.

    Take the final exam

    4.) Certificate: A passing grade of 70% or higher on the exam, is required to receive the certificate of completion for this PDH course.
         NOTE: After the exam is completed, you will need to return to this page, in order to print (download) the certificate of completion.

    Print the Certificate of Completion

    Intended Audience: This course is intended for surveying and engineering professionals whose job description may require an intermediate to advanced knowledge of GPS principles and procedures.
    Publication Source: USACE

    Donald Parnell, PE

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