Geog 121 Project 2: Locating Geographic Coordinates with GPS Dan Desiderio Allison Hurley Carlo Sica Valarie Troya

Introduction The Global Positioning System (abbreviated GPS), is the only fully-functional satellite navigation system. It was developed by the United States Department of Defense that launched the first experimental satellite in 1978. The system costs taxpayers $400 million dollars a year to maintain, and is free to use on the basis of “public good” Source: Encyclopedia Britannica

Introduction The Global Positioning System consists of three components: a space segment, a control segment, and a user segment. The space segment consists of a constellation of six equally spaced orbit planes, each occupied by four or more satellites. Satellites trace the same ground path every 12 hours at an altitude of 20,200 km. Five to eight satellites are in view everywhere on or near the Earth's surface at all times. Source: ESRB online text for 121

Introduction The control segment of the Global Positioning System is a network of ground stations that monitors the shape and velocity of the satellites' orbits. The accuracy of GPS data depends on knowing the positions of the satellites at all times. Data describing the orbits are produced at the Master Control Station at Colorado Springs, uploaded to the satellites, and finally broadcast as part of the GPS positioning signal. GPS receivers use this satellite "almanac" data to adjust the positions they measure. The Master Control Center can also modify satellite orbits when necessary.

Introduction The user segment of the Global Positioning System consists of the receivers that military personnel and civilians use to determine positions. GPS receivers contain electronics required to receive radio transmissions from NAVSTAR satellites, clocks to keep track of the timing of radio signals, and software to calculate positions based on those received signals. A GPS receiver calculates its distance from multiple satellite transmitters as a function of the time elapsed between when the signal was transmitted and when it was received. By calculating three or more such distances, the receiver can trilaterate its position on the Earth's surface – a process otherwise known as satellite ranging.

Navigating With Your GPS 12 - the “in-field” segment-

Finding the Waypoints Convert the decimal portions of the coordinates into minutes. Do this by multiplying the decimal portion by 60. The whole number in the product will be your minutes value, and the decimal will be a decimal portion of minutes (not a seconds value). Your GPS 12 unit only works in degrees and minutes, not seconds. Recheck your math, making sure calculations are accurate now will prevent problems later

Finding a Waypoint Once you have the correct coordinates press the page button until you get the waypoint screen Highlight Waypoints and select enter - Type coordinates into the GPS using the arrows

Finding a Waypoint Once desired points are saved press the GoTo button on the top left Select the point you want to navigate to The compass page will lead you to the destination

Marking Your Own Waypoints You’ll need to mark four of your own points on campus To document your present location hold the Mark button Enter the name of the point (using the up and down arrow button, select save and press enter That point should be saved on the Waypoint list from the screen before

Helpful Hints Make sure you calculate accurately -- A small error can cause a lot of problems when searching for the point (about 3 hours in our experience) Your units should be converted into minutes and decimal fractions of minutes –NOT SECONDS Manual for GPS Unit (also on ANGEL, under “Lessons”: https://cms.psu.edu/section/default.asp?id=MRG%2D060821%2D144613%2Dreb186

Integrating and Representing your data with ArcMAP - the computer portion-

Downloading Your Waypoints 1. Plug in your GPS device using the corresponding cable. * make sure that the GPS is turned ON * 2. go to START and find the program WAYPOINT a) open Waypoint+v1.8.03 b) click Waypoint and choose “download”

c) click File and choose “configuration” - coordinates = Decimal Degrees - units = Statute Miles. d) click File and choose “datum” - scroll down to find WGS84 - click to highlight and press “ok”

3. Now that your Waypoint data is properly configured you will want to save your GPS data as a text file. To do this: File > Save > Waypoint * I saved mine under the C:\ drive as a temporary file and then re-saved it under my W drive after (this actually made it easier when I had to import it in ArcView) …if you do this be sure you save it to your W drive as well!!

Putting Your Data into a Spread Sheet on Excel 1. Open Microsoft Excel 2. Open the Waypoint that you just saved. - Text Import Wizard will pop up > It will ask you to choose how you want your data displayed (there is more than one way to have your data displayed in excel, so just play around with it, as long as you eliminate any extra spaces or commas you will be on the right track) 3. Now to work with the data points in ArcMap you will want your decimals to be in columns of Latitude and Longitude

Your data should appear in columns… Reformat the text so that it looks like this… This will allow ArcMap to recognize you coordinates so that they will be plotted on your map.

See how there are NO commas or extra spaces in our text file… THIS IS VERY IMPORTANT!

How to Build Your Map Ok, now you are going to construct a map of campus (west – central) so that you can display the data you downloaded as points… First, you’ll want to go onto ANGEL. Under lessons choose: “Project 2b: Campus Map Data” - download the zip file and save it (to do this I created a temporary folder on my desktop; you’ll have a few windows open during this process and this made it easier to work with)

Creating Map Layers You’ll want to use these shapes in your layers on your map… 1. START > PROGRAMS > ArcGIS > ArcMap a) once ArcMap is open: - open the folder where you saved your shape files in. - your first choice should be named something like “campus_spc_nad83” - this is what you’ll be working with. b) in ArcMap; - click View and choose “Data Frame Properties.” - click the Coordinate System Tab - click Import - use the data source: Folder > Campus Shape Files - click “Add” button c) Now look under <custom> folder. - you want to choose: NAD_1983_StatePlane_Pennsylvania_North_FIPS_3701_Feet - click “Apply” - click “Ok”

2. Now click to highlight the word “Layers” You can either choose Add data from the File menu or drag the shape files from your desktop folder into ArcMap. (clip_mask.shp will be your bottom layer) 2. Now click to highlight the word “Layers”

Plotting your Points on ArcMap 1. Go to Tools Menu > Add XY Data - Locate your waypoint data text file - should be something like: waypoints.txt (This can take awhile if you save it in an obscure folder, this is why saving it in your C:\ drive makes it easier to work with) 2. After you find it, click it and pick “Add”

3. the windows which say X field and Y field they should now say Longitude and Latitude respectively. *if it doesn’t say Long/Lat double check if your text file displays your points as Long/Lat * * Also making sure your file is closed BEFORE you add the XY Data in ArcMap should eliminate problems here *

Creating a Spatial Reference Description: 1. You will click on “Edit” - in the Spatial Reference Properties window press “Select” 2. In the Browse for Coordinate System window browse to: > Geographic Coordinate Systems > World > WGS 1984 3. Back in the Spatial Reference Properties window, click “Ok” 4. Then in the Add XY Data window, press “Ok”

So what is WGS84? * WGS84 stands for World Geodetic System 1984, it is the geodetic reference system used by GPS. * It was originally developed for the United States Mapping Agency. Since 1984 is have been re-modified. * All GPS receivers compute and store waypoints in terms of WGS84 then transform them into other datums when displaying information. *Hence it makes sense that WGS84 is the default datum for most GIS software packages

Your map should have your points displayed correctly  Now the “fun” begins… - You can play with the colors of the map layers by right clicking on an individual layer and choosing a new color - You can also change the way your points are displayed using the same process

Your final map should display your points in the correct locations…

Useful Resources For more help in understanding these steps go to: http://www.acadweb.wwu.edu/gis/tutorials/Getting_GPS_data_into_ArcGIS.doc …you would be following Method 2a. Step-by-step guide by group member Allison Hurley: http://www.personal.psu.edu/arh5041/handout.html

Citations: “What is the difference between WGS84 and GDA94.” 2000. Inter-governmental Committee on Surveying and Mapping. October 8, 2006. <www.icsm.gov.au/icsm/gda/wgs84fact.pdf> Baxter, Ryan. “GEOG121 Project 2b: Integrating GOS and GIS.” October 6, 2006. <http://www.geog.psu.edu/courses/geog121/projects/proj2b.html> "Global Positioning System," Microsoft® Encarta® Online Encyclopedia 2006 © 1997-2006 Microsoft Corporation. All Rights Reserved. October 7, 2006. <http://encarta.msn.com> Dana, Peter H. (1998) Global Positioning System Overview. The Geographer's Craft Project, Department of Geography, The University of Texas at Austin. Accessed 2 August 1999. <http://www.colorado.edu/geography/gcraft/notes/gps/gps.html>