Method and apparatus for measuring optical turbulence using an unmanned aerial vehicle

An unmanned aerial vehicle used for measuring optical turbulence comprising:

• a) a first temperature sensor, operatively connected to a central processing board, configured to generate first temperature measurement information at a first sampling rate, wherein the first temperature measurement information is associated with a first temperature at the first temperature sensor during a first period of time defined by a first start time and a first end time;
• b) a second temperature sensor, operatively connected to the central processing board, configured to generate second temperature measurement information at the first sampling rate, wherein the second temperature measurement information is associated with a second temperature at the second temperature sensor during the first period of time;
• c) a first wind speed sensor, operatively connected to the central processing board, configured to generate first wind speed measurement information at the first sampling rate, wherein the first wind speed measurement information is associated with a first wind speed at the first wind speed sensor during the first period of time;
• d) a first barometric pressure sensor, operatively connected to the central processing board, configured to generate first barometric pressure measurement information at the first sampling rate, wherein the first barometric pressure measurement information is associated with a first barometric pressure at the first barometric pressure sensor during the first period of time;
• e) the central processing board, configured to:
• i. receive, from the first temperature sensor, the first temperature measurement information generated during the first period of time;
• ii. receive, from the second temperature sensor, the second temperature measurement information generated during the first period of time;
• iii. receive, from the first wind speed sensor, the first wind speed measurement information generated during the first period of time;
• iv. receive, from the first barometric pressure sensor, the first barometric pressure measurement information generated during the first period of time;
• v. store, in memory operatively connected to the central processing board, the first temperature measurement information, the second temperature measurement information, the first wind speed measurement information, and the first barometric pressure measurement information;
• f) a digital software system operably connected to the memory, wherein the digital software system is configured to:
• i. obtain from the memory the first temperature measurement information, the second temperature measurement information, the first wind speed measurement information, and the first barometric pressure measurement information;
• ii. determine:
• 1. first power spectral density information associated with a first plurality of frequencies based at least on the first temperature measurement information;
• 2. second power spectral density information associated with the first plurality of frequencies based at least on the first wind speed measurement information;
• 3. a first sensor cutoff frequency associated with at least one of the first temperature sensor and the first wind speed sensor;
• and
• 4. third power spectral density information associated with the first plurality of frequencies based at least on the second temperature measurement information;
• iii. decimate the first temperature measurement information, the first wind speed measurement information, and the first barometric pressure measurement information to a second sampling rate during the first period of time based at least on the first power spectral density information, the second power spectral density information, and the first sensor cutoff frequency;
• iv. decimate the second temperature measurement information to the second sampling rate based at least on the third power spectral density information;
• v. calculate a first estimated sensor spacing value based at least on the decimated first wind speed measurement information, and the first start time and the first end time associated with the first period of time;
• vi. determine a first temperature structure coefficient based at least on the first estimated sensor spacing value and the decimated first temperature measurement information during the first period of time;
• vii. determine a second temperature structure coefficient based at least on the first estimated sensor spacing value and the decimated second temperature measurement information during the first period of time;
• viii. determine a first refractive-index structure coefficient indicative of optical turbulence during the first period of time based at least on the first temperature structure coefficient, the decimated first temperature measurement information, and the decimated first barometric pressure measurement information;
• ix. determine a second refractive-index structure coefficient indicative of optical turbulence during the first period of time based at least on the second temperature structure coefficient, the decimated second temperature measurement information, and the first barometric pressure measurement information;
• and
• x. transmit, to an optical system, the first refractive-index structure coefficient and the second refractive-index structure coefficient.