Unit 3: Static GPS/GNSS Methods
The application of Global Navigation Satellite Systems (GNSS) in the earth sciences has become commonplace. GNSS data can produce high-accuracy, high-resolution measurements in common reference frames. Static GNSS methods take advantage of long occupation times to resolve fine measurements and time-series data to capture events such as tectonic deformation, earthquakes, groundwater depletion, and slow-moving landforms. This unit focuses on design and field execution of simple static surveys, emphasizing the benefits and limitations of the technique. Students will learn which applications the technique is most applicable for, as well as the standard data-processing techniques. Additionally, students advance their understanding of GNSS systems through interpretation of field data from static surveys and public data sets of continuous-operation stations. This unit prepares students to design and implement a survey of their own through hands-on instruction and demonstration of rapid-static or static techniques in a field setting.
Unit 3 Learning Outcomes
- Students are able to list the components of a static system, describe their function, and discuss how they integrate into the system as a whole
- Students are able to design, conduct, and process results for a simple survey.
- Students are able to analyze and interpret static GNSS station positions.
- Students can apply findings from static GNSS observations to an issue important to society.
Unit 3 Teaching Objectives
- Cognitive: Teach students to make decisions on balancing numerous competing factors in designing the optimal static GNSS survey for a given location or problem.
- Behavioral: Promote students' ability to assemble and operate a static GNSS antenna, receiver, and related equipment and make supporting field observations.
- Affective: Share with students the value of the high-accuracy positioning possible with static systems, giving examples such as measuring earthquakes, volcanic inflation, groundwater depletion, landslide dynamics, or tectonic deformation.
Context for Use
This unit is appropriate for upper division geoscience, earth science, geography or civil/environmental engineering students who have already been introduced to basic concepts such as plate tectonics, mass movements, and hydrology. Students should also have a first-order familiarity with uncertainty, precision, and accuracy and the science behind GNSS systems (Unit 1: GPS/GNSS Fundamentals). It is not necessary to have completed any parts of Unit 2: Kinematic GPS/GNSS Methods in order to teach Unit 3. The unit is appropriate for academic year courses with field components or a summer field camp.
This unit builds upon Unit 1's fundamentals (such as GNSS systems, precision, accuracy and uncertainty) and assumes that users have either completed Unit 1 or had previous training in GNSS concepts and terminology. This unit is designed for a mixed classroom/field setting. However, we encourage that the initial lecture be followed by a field experience with hands-on demonstration of static GNSS equipment or a visit to a NOTA or other permanent static GPS site. Students should use printed handouts for note taking, either directly or as a guide for personal field books.
The final portion of the unit requires computer access with GNSS processing software appropriate to the brand of hardware used. An internet connection is not mandatory, but it will require additional preparatory work if a connection is not available. This unit requires that either pre-processed data is available for students (from a previous year or occupation, for example) or that additional time is accounted for processing positional data. OPUS is currently the best possible solution for a rapid processing, although it is not the best in terms of absolute accuracy (a few centimeters at best). Using OPUS typically requires a 24-hour period between acquiring data and submitting it for processing. This means the course can be ideal for interleaving other activities or academic semester courses where this time is not an issue. In a field camp setting, it may be easiest to have prepared or pre-processed results or the ability to return to the GNSS project after a few days.
Description and Teaching Materials
This unit begins with an introduction to static survey systems through a lecture and introduction to the Static GPS/GNSS Survey Methods Manual. The lecture is presented with a PowerPoint that illustrates static surveys, their applications and advantages, a brief processing overview, and a review of interpreting position results. During or after the lecture, students should be presented with the Static GPS/GNSS Survey Methods Manual. This manual introduces students to the various types of static surveys, equipment, and methods for a successful survey. The methods include survey design, execution, and processing. It is not critical to read the manual in its entirety but for students to understand the basic components of a system and the general steps for a successful survey. The lecture and manual introduction should take at most one hour. Following the lecture and the introduction to the manual, a short field component should introduce students to the static GNSS hardware either through a hands-on demonstration of setting up a unit over a benchmark or a visit to a permanent, continuous station like a NOTA site. The field component should also require ~1 hour.
After being introduced to the manual, students should be given the 'Introduction to Time Series' assignment. This assignment will correlate with the last part of the lecture and ask students to interpret static GNSS data from continuously operating and campaign sites. Though there are already sites selected for the assignment, you can modify this to address a different field area. The assignment solidifies the concept of position velocities, vectors, and interpretation of events in a time series. Students will need a small ruler, pencil, and possibly a calculator for the assignment. The assignment should take students 1 to 1.5 hours.
2) Simple Rapid-Static Survey
Students should be provided with the necessary equipment and take part in an example static survey including setting up equipment, collecting metadata, surveying the location, processing data, and reading results. Students should be guided through the Static GPS/GNSS Survey Methods Manual as the instructor demonstrates proper set up and data collection. Students should then get hands-on experience with the equipment and survey a location. They will survey one or more locations and fill out thorough field notes about both the field site (example field notebook (Acrobat (PDF) 1.4MB Dec2 16)) and the monument (monument visit logsheet).
It is advantageous here to have several pieces of equipment so that no more than 4 or 5 students are working at a single receiver. Students can rotate jobs between writing notes, taking measurements, and operating the receiver. Typically, a rapid-static survey (occupation of at least 15 minutes to 2 hours) will be ideal, unless this activity can be alternated or interleaved with another activity. When the survey is complete, students should then be shown how to retrieve RINEX data files from the receivers and process them through an appropriate program. For those using OPUS there are instructions in both the Static GPS/GNSS Survey Methods Manual and the stand-alone Static GPS/GNSS Data Processing with OPUS Manual. If there is access to an internet connection, students can process through OPUS directly; if not, pre-processed results are needed. The survey, processing and interpretation should take ~3 hours, not including the OPUS wait time.
Note: OPUS requires approximately 24 hours before positional corrections are available for a given time period. That means you will need to account for this time delay with another activity. If you are teaching Kinematic GNSS as well, a static survey can be set up first and allowed to run while the other unit is taught. Once data is submitted to OPUS for processing, results are typically returned within 1 or 2 hours. Be prepared with an alternative data set if OPUS fails to return a corrected position.
- Unit 3 Static GNSS Lecture (PowerPoint 2007 (.pptx) 10.7MB Nov20 23)
- Presentation: basics of static GNSS
- Unit 3 Introduction to GNSS Time Series - Borah Fault, Idaho (Microsoft Word 2007 (.docx) 4.2MB Oct6 23)
Unit 3 Introduction to GNSS Time Series - Borah Fault, Idaho PDF (Acrobat (PDF) 1.7MB Oct6 23)
Unit 3 Introduction to GNSS Time Series - Borah Fault, Idaho - Answer Key -- private instructor-only file
- Student exercise: students gain familiarity with time-series of GNSS positions, learn to interpret signals and noise, and apply this interpretation to a scientific question.
- Alternative: Unit 3 Introduction to GNSS Time Series - Cook Inlet, AK (Microsoft Word 2007 (.docx) 2.1MB Oct6 23)
Unit 3 Introduction to GNSS Time Series - Cook Inlet, AK PDF (Acrobat (PDF) 1.6MB Oct6 23)
- Unit 3 Introduction to Static GNSS Surveys Student Exercise (Microsoft Word 2007 (.docx) 213kB Apr16 18)
Unit 3 Introduction to Static GNSS Surveys Student Exercise PDF (Acrobat (PDF) 435kB Apr16 18)
- Student exercise: students complete an introductory static survey. Students get hands-on time with equipment to become familiar with its use before applying skills in the summative assessment.
- Unit 3 Summative Assignment Leveling Line Analysis with Static GNSS (Microsoft Word 2007 (.docx) 211kB Oct6 23)
Unit 3 Summative Assignment Leveling Line Analysis with Static GNSS PDF (Acrobat (PDF) 222kB Oct6 23)
- Summative assignment: students design and conduct a GNSS survey that adds new data to a previous static occupation. Students then interpret their results in light of historical data.
- Static GPS/GNSS Survey Methods Manual (Microsoft Word 2007 (.docx) 9.1MB Oct6 23)
Static GPS/GNSS Survey Methods Manual PDF (Acrobat (PDF) 1.1MB Oct6 23)
- Guide for setting up, executing, and processing data a static GNSS survey
- Static GPS/GNSS Data Processing with OPUS Manual (Microsoft Word 2007 (.docx) 356kB Apr8 18)
Static GPS/GNSS Data Processing with OPUS Manual PDF (Acrobat (PDF) 563kB Apr8 18)
- Guide for post-processing static occupations with the online tool OPUS
- EarthScope GPS/GNSS Campaign Handbook (Microsoft Word 2007 (.docx) 2.7MB Oct6 23)
EarthScope GPS/GNSS Campaign Handbook PDF (Acrobat (PDF) 1.1MB Oct6 23)
- An initial guide for GNSS surveys. This covers the merits of various campaign types, data collection and processing, physical equipment setups, and monument logs. This can be given to students in the introduction so that they understand the depth of the material, take notes as necessary, and reference it when necessary. This was used as the basis for the "Static GPS/GNSS Survey Methods Manual" but contains additional information as well.
- TEQC tips for getting started (Microsoft Word 2007 (.docx) 151kB Oct6 23)
TEQC tips for getting started PDF (Acrobat (PDF) 125kB Oct6 23)
- TEQCis command-line software that can be used to Translate, Edit, and Quality Check GNSS data.
- Field Notebook Example (Acrobat (PDF) 1.4MB Dec2 16)
- Example field book layout suggested for students while taking notes for a GNSS survey.
- Monument Visit Logsheet
- It is critically important to accurately fill out a monument logsheet in order to have the information needed during processing.
Teaching Notes and Tips
The time-series exercise is best employed if it uses examples from local areas or sites that are significant for the survey students will complete later. For example, the original assignment is written for three stations distributed across the Borah Peak Fault, the feature that students would then survey a leveling line across. This allowed students to gain a tectonic motion perspective for the leveling line data they were acquiring and familiarized them with the relative merits of the two different approaches to a GNSS survey.
If you wish to adapt this to another region, you can search for stations using data interfaces such as:
- Network of the Americas Health Map. Zoom into your area of interest. Click on a individual station and then the station name to get to the station info and data page.
See how we did this for an area in Alaska here: Unit 3 Introduction to GNSS Time Series - Cook Inlet, AK (Microsoft Word 2007 (.docx) 2.1MB Oct6 23). Blank graph (see right) may also be helpful if the ones within the existing exercises are not the correct scale. Alternatively you could use the graphs in this EPS file Blank GPS plots used to make the AK assignment (Encapsulated Postscript 1MB Oct18 18)
Much of the formative assessment can be done through observations of and discussions with students individually, in pairs, or sometimes in the whole group. This should be done periodically throughout the process as it helps gauge student understanding and weaknesses. Students should be encouraged to answer their own questions through deductive reasoning. A large portion of the grading should be attributed to students' individual participation and contribution to the group effort. Students will turn in their student exercise. Questions should be graded for completeness.
The Summative Assessment is the Static Survey of a Leveling Line. Students measure a leveling line (or other campaign deployment scenario). Students should be assessed mostly on their ability to perform the survey and to place the survey's results in a broader context or social implication.
- Unit 3: Time-Series Analysis Exercise
References and Resources
- Videos for explaining GNSS:
- Resources for data processing
- Resources for benchmarking and standards
- National Geodetic Survey (NGS)
- NGS: Finding Survey Marks and Datasheets
- NGS: GPS on Bench Marks (GPS on BM) campaign
- P. H. Rydlund Jr. and B. K. Densmore. 2012. Methods of practice and guidelines for using survey-grade global navigation satellite systems (GNSS) to establish vertical datum in the United States Geological Survey: U.S. Geological Survey Techniques and Methods, book 11, chap. D1, 102 p.
- GAGE Knowledge Base has many resources on GPS/GNSS equipment and methods.
Additional Resources for Instructors:
Paper related to the time series exercise in Idaho
- S. J. Payne, R. McCaffrey, R. W. King, and S. A. Kattenhorn. 2012. A new interpretation of deformation rates in the Snake River Plain and adjacent basin and range regions based on GPS measurements, Geophysical Journal International, Volume 189, Issue 1, p 101–22, https://doi.org/10.1111/j.1365-246X.2012.05370.x.
Papers related to the time series exercise in Alaska
- Location and Extent of Tertiary Structures in Cook Inlet Basin, Alaska, and Mantle Dynamics that Focus Deformation and Subsidence, USGS Professional Paper 1776–D
- Haeussler et al., 2000. Potential seismic hazards and tectonics of the upper Cook Inlet basin, Alaska, based on analysis of Pliocene and younger deformation, Geological Society of America Bulletin, doi.org/10.1130/0016-7606(2000)112<1414:PSHATO>2.0.CO;2.