What are the specifications of the system and how can they be independently verified? These are the question that the Verification testing answers. There are three data inputs used to determine the aircraft's altitude. They are the camcorder sites' positions, the camcorder sites' altitudes, and the elevation angles from the sites to the aircraft. The first two inputs are taken directly from accepted industry standard sources. The U.S.'s Global Positioning Satellite (GPS) system, U.S. Geological Quadrangle maps and Ventura County Surveyors office of Horizontal Measurements. Since these are accepted industry standards, they do not have to be re-verified again for this system verification.

The elevation angle measurement from the site to the aircraft is the third data input. This measurement has to be verified. The camcorder was being used as a sextant to measure the number of degrees from the horizon to an object. The camcorder's videotape picture was used to determine the elevation angle to the aircraft. I needed to verify the camcorder's angle measurement the same way I would verify a sextant measurement accuracy. The United Sates Naval Observatory publishes a Nautical Almanac* that gives the elevation angle measurements to celestial objects. By knowing the camcorders latitude and longitude position, and the exact time and date you can determine the elevation angle to a celestial object by using the Nautical Almanac.

The camcorder's tracking of three celestial objects was documented. It tracked the planet Venus, the sun, and the moon. (See attached graphs, Sun vs. Video Template, and Moon Vs Video Template) All the recorded videotapes and data were saved for anyone who wants to independently verify the test results. The sea level is used as the horizon. The elevation angle was measured to a celestial object and then compared to the data in the Nautical Almanac. A GPS receiver was used to determine the position of the camcorder

The tracking of Venus could only be documented during the twilight because the sea level horizon could not be seen on the videotape after total darkness. The camcorder's documented accuracy for the twilight period was within +/- .1 degrees.

The tracking of the sun was done for 2 1/4 hours from 2:00 PM to 4:15 PM. Two shade filters were required. These filters were obtained from a welding supply store. A shade filter of #14 was required to videotape the sun portion of the screen. A shade filter of #8 was required to videotape the sea level horizon portion of the screen. The reflective glare off the ocean was too bright for the camcorder to videotape without a shade filter. The camcorder's documented accuracy was within +/- .3 degrees. This is .2 degree greater error than what was expected. A review of the videotape showed that the shade filter over the sea level horizon portion only let the glare off the water come through to the videotape. At high sun elevation angles the glare reflected of the water did not go all the way out to the horizon. As the sun got to a low elevation angle the accuracy increased because the glare went out further to the horizon.

The tracking of the moon was done for 35 minutes as it went from an elevation angle of 32 degrees to 37 degrees. This test setup was done since the moon would appear at the extreme top of the TV screen. This is where the maximum potential would be for system errors since the system uses the bottom of the TV screen (sea level) as the starting point. This test setup is the one which most closely duplicates the setup for monitoring low flying aircraft. The camcorder's documented accuracy was within +/- .1 degrees.

There were two more documented tests done (See attached graphs, Protractor Vs Video Template and Ruler Vs Video Template) which although believed to be accurate could not be accurately verified by an independent person using the supplied documentation. These test consisted of the camcorder's videotape of a giant protractor (5 feet high) and a videotape of a vertical ruler 94.5 inches away. An independent person would not be able to verify the exact placement of the camcorder's position during the test from the supplied documentation. The data from these two tests was used to make a template to later measure the elevation angle to the celestial objects. Since those celestial angle measurements were accurate to +/- .1 degree then the protractor and ruler test were indirectly verified.

Also there was the Validation test which used a laser range-finder to independently measure the altitude of the aircraft. The Validation tests showed that the camcorder's angle measurements are within +/- .2 degrees of this surveying equipment.

The +/- .2 degree error would result in an aircraft altitude error of +/- 3.7 feet for an aircraft 1000 feet away. This accuracy is five to ten times more accurate than what is required for this Low Flying Aircraft Monitoring System to be useful for measuring the altitude of airplanes.