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… maintains high GPS signal quality and strength for reduced flight time and improved aerial imaging efficiency
NASA Goddard Space Flight Center offers this low-cost solution to significantly reduce time and costs associated with precision aerial GPS antenna applications. This GPS antenna positioning system offers significant benefits for aerial surveying and other aerial applications requiring very high (centimeter level) aircraft positioning.
It is critical when performing aerial mapping and surveying to maintain a constant lock on each of the GPS positioning satellites. Even very brief (nanosecond), losses of signal can degrade the accuracy of the aircraft position measurement. In order to avoid these cycle slips, pilots performing aerial surveys and other precision flights typically limit their bank angle during turns to 10 degrees or less. This small angle allows them to maintain constant contact with the each of the GPS satellites in the constellation but can require five minutes or more to turn the aircraft around in order to begin the next pass. With even average size surveys, the maneuvering time can be considerable and can often exceed the time spent doing the actual survey. For example, surveying a region may take over 300 flight lines with turns at each end. Using a ten-degree bank results in only 40%* of the overall flight time being spent conducting the survey—the rest is spent turning and maneuvering the aircraft. This not only uses more fuel, it also takes much more time resulting in more expensive surveys. * Note: The percent of time spent in turns depends upon aircraft speed as well as the length and number of flight lines. NASA’s GPS antenna positioning system addresses this problem and increases flight productivity and efficiency. How it works
Why it is better More flight time is spent on the desired flight lines and less flight time is wasted in turns. This system enables aircraft banks of up to 30 degrees without loss of lock on GPS signals. This decreases turning time from five minutes to approximately one minute on a typical survey aircraft.
NASA Goddard Space Flight Center has patented this technology (U.S. Patent #6,844,856) (Link opens new browser window) This technology is part of NASA’s Innovative Partnerships Program Office, which seeks to transfer technology into and out of NASA to benefit the space program and U.S. industry. NASA invites companies to consider licensing the Precision Airborne GPS Antenna Positioning System (GSC-14436-1) for commercial applications. For information and forms related to the technology licensing and partnering process, please visit the Licensing and Partnering page. (Link opens new browser window) If you are interested in more information or want to pursue transfer of this technology, please contact: Innovative Partnerships Program Office
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The airborne LIDAR industry relies on precision GPS positioning for producing high accuracy topographic surveys and aerial photography orthorectification. Loss of GPS signal, known as cycle slips, for even nanoseconds can seriously degrade the accuracy of the survey. To reduce the occurrence of cycle slips, pilots limit aircraft bank angles to less than 10 degrees, which increases survey time considerably. This innovative GPS antenna system reduces loss of signal by sensing changes in aircraft attitude and automatically adjusting the antenna to maintain the signal strength and quality.
The aerial GPS antenna positioning system is mounted on a motor-driven gimbal on the aircraft. The aircraft’s roll attitude sensor sends digital roll information to the gimbal via an onboard microcontroller. As the aircraft banks, the motorized gimbal rotates the antenna assembly in the opposite direction to the aircraft roll, thus keeping it level and parallel to the Earth. (See figure at right) This rotation maintains high signal strength and quality with each GPS satellite in the constellation.
