Given:

• Satellite Coordinates (matlab file)
  Cartesian coordinates for satellites 1-31 between noon and 1 p.m. local time, CU Engineering Center.

• latitude/longitude/height software

• elevation angle software

• azimuth angle software

• The Cartesian coordinates of the Engineering Center Roof (aero portion)

    X= -1288173.0679 Y= -4720793.9294 Z = 4079711.3975

Goals:

• Get you outside while the weather is still decent.

• Give you a feel for the number of GPS satellites and its geometry in Boulder.

Description

• Read the entire lab description.

• Pick up a Garmin receiver from the instructor - go outside with it and a piece of paper and pen or pencil.

• Turn on your receiver and check the different screens for as long as you like. Sketch the location of the satellites in an azimuth-elevation angle plot. Azimuth directions are noted on the outside of the circle. We do not use the usual polar plotting convention. In geodesy, north is zero and azimuth is defined clockwise. Elevation angles are the interior circles, with elevation angle of 90 in the center and elevation angle of zero in the outermost circle (see plot below).

• Your main code should:
  • Define the location of the CU Engineering Center.

  • Calculate local up vector.

  • Load the satellite coordinates.

    The variable SatPos is dimensioned (12 3 31). The first index gives you time since noon in 5 minute increments, i.e. 1 is noon and 12 is 12:55 p.m. The second index gives you X, Y, Z for the satellite in meters. The third index tells you the satellite name. At least three of the satellites are empty (i.e. the X, Y, Z coordinates are zero). This is because the constellation currently only has 28 satellites.

  • For noon local time, compute the elevation angle of each satellite. For those above an elevation angle of zero degrees, compute the azimuth angle. For 12:55 local time, compute the elevation and azimuth angles for these same satellites. Save these values into new variables so that you can plot them.

  • Make an azimuth elevation angle plot for your satellite locations. Use a maximum magnitude of 1 (for elevation angle of zero degrees). Go ahead and use Matlab's polar plotting program, although remember it defines angles differently than I do. If you define neg_azimuth = -1*azimuth, this command polar(neg_azimuth, rho,'o') will at least put your satellites in the correct quadrants - otherwise, they are the mirror image. Use a different symbol for the 12:00 and 12:55 positions so you can determine which satellites are rising and which are setting. You will need to cross out and correct the incorrect azimuth labels.

  • Put the names of the satellites on your plot. The easiest way is to use the text command. Define north, east, south, and west with pencil or pen.

  Turn in:

  • Your code.

  • Your plot (I don't need your sketch - that is just a reality check for you).

Azel Plot: