DEPARTMENT OF GEOGRAPHY UNIVERSITY OF FLORIDA PHYSICAL GEOGRAPHY LAB. GEO 2200L Lab 9: GPS ∙ http://www.colorado.edu/geography/gcraft/notes/gps/gps.html ∙ http://www.howstuffworks.com/gps.htm ∙ http://www.geocaching.com/ To answer the following questions: 1. What does the acronym GPS stand for and what does the GPS system do? (2 marks) ∙ Global Positioning System ∙ Used for navigation worldwide ∙ Useful for taking data points or control points when working in the field ∙ Can also be used for mapmaking, commerce, scientific research, and just plain fun (GEOCACHING) 2. List the three segments of GPS and briefly explain each segment. (6 marks) ∙ Pace segment: This consists of the satellites that are orbiting in space. ∙ User segment: The community of persons with GPS receivers ∙ Control segment: The tracking stations that are located across the globe 3. By whom and why was it developed? (2 marks) ∙ Development of the $10 billion GPS satellite navigation system was begun in the 1970s by the US Department of Defense ∙ Military purpose then open to public 4. For GPS, measurements of codephase arrival time from at least how many satellites are used to estimate four quantities: position in three dimensions (X,Y,Z) and GPS time (T)? (1 mark) ∙ 4 5. Explain what 2d trilateration is. Use diagrams if necessary. (3 marks) A trilateration is the process of determining absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles. A 2d trilateration is precise enough to give an exact location 6. What is the difference between 2D and 3D trilateration? Use diagrams if necessary. (1 mark) ∙ 2D trilateration works with distance while 3D trilateration works with angles. 7. How does a GPS receiver determine the distance between you and the satellites? (2 marks) ∙ GPS uses 3D trilateration to determine a user's position. To be able to apply 3D trilateration, we need to know the exact distance that our GPS receiver is from the orbiting satellites to be able to calculate an accurate position. By applying some basic mathematics the receiver can work out this distance 8. What causes GPS satellites to vary in orbit and how is this inaccuracy corrected? (2 marks) ∙ Atmospheric and equipment conditions cause variations. Inaccuracy is corrected by using the DGPS or the Differential GPS 9. Name 3 different ways in which GPS satellites may give signals that are inaccurate and state one way in which this can be corrected? (4 marks) ∙ The travel time of GPS satellite signals can be altered by atmospheric effects; when a GPS signal passes through the ionosphere and troposphere it is refracted, causing the speed of the signal to be different from the speed of a GPS signal in space. Sunspot activity also causes interference with GPS signals. Another source of error is measurement noise, or distortion of the signal caused by electrical interference or errors inherent in the GPS receiver itself. Signal errors can be reduced by differential correction10. What is a waypoint? Hint: do a search for this on your own. (1 mark) ∙ A waypoint is a fixed location with specified coordinates. 11. i) What is WAAS, ii) how does it help to improve GPS accuracy? iii) How much more accurate can the signal be? (3 marks) WAAS Wide Area Augmentation System. It helps improve GPS accuracy because it seeks to eliminate small deviations in the goal of improving accuracy to enable aircraft to rely on GPS for all phases of flight. It uses a network of ground based systems, which take the deviations, correct them and send them back in 5 seconds or less. WAAS specification requires it to provide a position accuracy of 25 ft or better at least 95% of the time 12. List five ways a GPS receiver can be used? (5 marks) ∙ Military operations ∙ Driving Directions ∙ Taking pictures and mapping areas of the Earth ∙ Using GPSguided equipment is used to apply fertilizer in agriculture in specific areas ∙ Damage assessment after natural disasters ∙ Navigation for planes 13. What is Geocaching and how does it work? (2 marks) Geocaching is an outdoor treasurehunting game in which the participants use a Global Positioning System (GPS) receiver or other navigational techniques to hide and seek containers (called "geocaches" or "caches") anywhere in the world 14. What is the difference between the coarseacquisition code and the precise code? (1 mark) ∙ The CourseAcquisition (C/A) code, sometimes called the Standard Positioning Service (SPS), is a pseudorandom noise code that is modulated onto the L1 carrier. Because initial point positioning tests using the C/A code resulted in better than expected positions, the DoD directed "Selective Availability" (SA) in order to deny full system accuracy to unauthorized users. SA is the intentional corruption of the GPS satellite clocks and the Broadcast Ephemerides. Errors are introduced into the fundamental frequency of the GPS clocks. This clock "dithering" affects the satellite clock corrections, as well as the pseudorange observables. Errors are introduced into the Broadcast Ephemerides by truncating the orbital information in the navigation message. ∙ The Precision (P) code, sometimes called the Precise Positioning Service (PPS), is modulated onto the L1 and L2 carriers allowing for the removal of the first order effects of the ionosphere. The P code is referred to as the Y code if encrypted. Y code is actually the combination of the P code and a W encryption code and requires a DoD authorized receiver to use it. Originally the encryption was intended as a means to safeguard the signal from being corrupted by interference, jamming, or falsified signals with the GPS signature. Because of the intent to protect against "spoofing," the encryption is referred to as "Antispoofing" (AS). AS is either "on" or it's "off;" there is no variable effect of AS as there is with SA. 15. List three important characteristics of carrier phase tracking (3 marks) 1. All carrierphase tracking is differential, requiring both a reference and remote receiver tracking carrier phases at the same time. 2. Using L1L2 ionospheric measurements and long measurement averaging periods, relative positions of fixed sites can be determined over baselines of hundreds of kilometers. 3. Two receivers and one SV over time result in single differences Total: 38 marks DEPARTMENT OF GEOGRAPHY UNIVERSITY OF FLORIDA PHYSICAL GEOGRAPHY LAB. GEO 2200LLab 10: Google Earth The following links are really useful! http://earth.google.com/userguide/v4/ug_keyboard.html http://earth.google.com/userguide/v4/ug_measuring.html Part 1: Learning Google Earth Follow your instructor to install Google Earth. Search for you and your partner’s home addresses: Compare the two locations: Elevation and the coordinates are located at the bottom of the map. Practice: zooming in and out rotating left and right tilting up and down
Lat and Long coordinates
N 36°35’12.48” W 82°08’54.24”
For GPS, measurements of codephase arrival time from at least how many satellites are used to estimate four quantities: position in three dimensions (X,Y,Z) and GPS time (T)?
By whom and why was it developed?
What does the acronym GPS stand for and what does the GPS system do?
If you want to learn more check out - all the experiences that you have had, causes you to develop certain beliefs or values (challenge in comm) b/c communicators have to deal with that “frame of reference” to solve you have to do your homework…what are the characteristics of the audien
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1. Make sure both addresses are checked in the list on the left and using the RULER tool under TOOLS determine how far apart the two homes are in Miles and Feet. You may have to zoom out to view both points.(1 mark) ∙ 479.76 2. Find the latitude and longitude coordinates of ground zero (9/11) hint: search for Church St and Vesey Street, New York City(1 mark) ∙ 40.7118° N, 74.0131° W 3. Give the name of the hotel that is found nearest to ground zero. (1 mark) The W New York Downtown4. What is the highest point of Mount Everest? (1 mark) Find it. Then use the TILT (hold control key and scroll your mouse to change the perspective between 90° and 180°. Use the ROTATE buttons to rotate around the mountain and view the different approaches to the top. It will be easier to find if you turn on the BORDERS and GEOGRAPHIC FEATURES layers on the left side Use the RESET NORTH button and tilt back to a vertical view. Both are located under the rotate buttons. 5. Give the latitude and longitude coordinates for the Orange Bowl stadium. (2 marks) Latitude: N 25.9580° Longitude: W 80.2389° 6. What is the closest bar to the stadium? hint: look in layers (1 mark) Mint Lounge 7. What is the closest park called? (1 mark) Moore Park Turn off all layers you turned on, except GEOGRAPHIC FEATURES 8. What famous man made structure lies at N 36 00 58, W 114 44 15? (1 mark) (use PLACEMARK tool if necessary) Turn on LAT/LON Grid under view Once you find the point, the TILT and ROTATE feature may help you to identify it. hint: keep the latitude and longitude lines vertical and horizontal as you search The Hoover Dam 9. What is the name of the lake that is created? (1 mark)Lake Mead Turn off LAT/LON Grid Zoom in until you find Central Park, New York City (hint: it is in Manhattan) 10. Use the layers provided by Google Earth and name the streets that form the perimeter of that park. (4 marks) Central Park S, Central Park W, 5th Ave, W 110th Street 11. Look up the formula for area and use the measure tool to calculate the area of Central Park, New York. Give your answer in acres. (Use http://www.ezcalculators.com/land_acre_conversion_calculator.htm if necessary.)(1 mark) 12. Find the Golden Gate Bridge. Using Google Earth alone, what evidence is there to strongly suggest a fee for use of the bridge? (1 mark) ∙ Toll station: 37°48’26.09”N and 122°28’32.18”W Use the local search box and type in Lombard Street, San Francisco, CA and do the following: Turn on the buildings and terrain layer (and turn off the latitude/longitude layer). Rotate the image to the left until you are looking down Lombard Street. Tilt the image down until you are looking down the street. (Hint, you may need to drag image down Lombard Street) 13. State why this street is hazardous and state why it has become a major tourist attraction. (2 marks) ∙ Very steep, 8 sharp turns14. Navigate to the MidAtlantic Ridge in the South Atlantic and find Ascension Island. Look at the image and briefly describe the terrain (landscape) of that island. Hint: you may need an atlas to find Ascension Island. (2 marks) ∙ Terraine is rocky, steep, uneven, covered in volcanoes and volcanic cones and caters. Turn off all layers and in the search box, type in these coordinates: 35.358 N, 138.731 E and when the location is found, turn on the geographic features layer and answer the following questions: 15. What is the name of the mountain? (1 mark) Mt Fuji 16. What is its elevation in feet? (hint: one of the links gives the answer). State the year of its last eruption. (2 marks) 12,388, 1707 17. Would you consider this a dormant volcano? (Please do the research and give a reason for your answer). (2 mark) Active because National Geographic experts warn its overdue for an eruptionTotal: 25 marks