Instructors:
Donald E. Mullins
Carlyle C. Brewster
Lectures:
Wed, 11:15 am-12:05 pm
221 & 301A Price Hall
Laboratories:
Thurs, 12:30 pm - 3:20 pm
300B & 301A Price Hall
Course Info:
ALS 5204
Index #96070
3 Credit Hours
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Lab 3: Geospatial Technology 1
Dynamics of GPS Readings

Download a copy of this document in MSWord or pdf formats.

Introduction

A personal handheld GPS receiver will not always give you the true geographic position of an object on the earth. The position as recorded by the GPS unit usually will differ from the position as determined by the GPS satellites orbiting the earth.

Your assignment (if you choose to accept it) is to track of the geographic position of a stationary object with your handheld GPS unit. That is, you are to determine the accuracy of readings recorded by a GPS unit.

Defintions

Accuracy is the nearness of a measurement to the actual value of the variable being measured.

Precision refers to the closeness to each other of repeated measurements of the same quantity.


Several GPS units will be made available for the study.

Purpose:
  1. To learn about GPS technology
  2. To use the GPS project to help with your understanding of the Scientific Method (Lecture 2) and Experimental Design (Lecture 8).
  3. To learn how to upload scientific data and results (graphs, figures, tables, etc. to a web site.
  4. To use the GPS data collected to develop a Scientific Poster Presentation (Lab 12).


Procedure:

  1. You are to treat the exercise as a scientific (statistical) study. This means that you must follow the scientific method (Lecture 2) to develop and carry out the study.
  2. You are to select an object on the Virginia Tech campus and record its geographic position throughout the study. The object you select should:

    • Be one that is unlikely to move or be moved during the course of the study. Why?
    • Not be hidden from the open sky. Why?
  3. Record the geographic position of the object with a handheld GPS unit using the Universal Transverse Mercator (UTM) coordinate system. In what UTM zone is your object located?
  4. Use the same GPS receiver throughout the study. Why?
  5. Take GPS readings on the object twice daily once in the morning and again in the afternoon.

    • The reading should be taken at about the same times (for example, between 8:00 and 9:00 AM and 3:00 and 4:00 PM) each day. At each time, you should record the position over a period of 5-10 minutes so that you could estimate the precision of the reading. You might, for example, want to record the reading every 2 minutes over the 10 minute sampling period.
    • Readings should be taken between 07th and 28th September for at least 10 days. The more readings you take, the better will be your estimate of the true geographic position of the object.
    • Different individuals should consider using their GPS to record the location of the same object. The data then can be shared. Doing this will increase the size of the data set and would allow you to add another dimension (treatment or factor) to your experimental design. This will become clear after you have had Lecture 8 (Designing Research Projects).

  6. At the time readings are taken you should also record any extraneous information such as weather conditions, etc. This information may help you explain your results. In Lecture 8, we will talk about extraneous factors.
  7. Use descriptive statistics and exploratory data analysis (Lecture 9) methods to describe the data you collect and to prepare a visual display (graph/plot/chart, etc.) of the results. Although not required, feel free to perform any appropriate type of statistical analyses on your data. Explain your results.
  8. You will be required to upload the project description, data, results, graphs, discussion, etc., to your web page.
  9. If you work in groups each member of a group can use the same data, but will be required to upload the report to their web site.

Your Write-Up:
Items to consider for your write-up (Lecture 2: Scientific Method, and Lectures 8 and 9):
  1. A description of your research hypothesis (see Lecture 2: Scientific Method). You are required to develop an EndNote library of references to support your research hypothesis.
  2. A statement of the objective of the study.
  3. The null and alterative hypotheses.
  4. The components of the experiment (factors and levels, response variable(s), etc.).
  5. Type of data you collected
  6. Whether the study was experimental or observational, prospective or retrospective.
  7. The type of data analysis that you might use based on the data that are collected.
  8. References
 

The write-up for this assignment should appear on your web site by October 26th in 3 formats: HTML, MSWord, and pdf.

Remember, you will be using the project to develop a poster presentation on Oct.26th.