Remote airflow observation device, remote airflow observation method, and program

A remote airflow observation method, comprising:

• radiating transmission light including pulse-form laser light;
• receiving reflected light of the radiated transmission light as reception light;
• outputting a received signal for calculating a wind speed value on a basis of the transmission light and the reception light;
• configuring a measurement unit including an optical system to radiate the transmission light and a movable optical mirror or prism configured to change a path of the transmission light output from the optical system;
• configuring an aircraft information acquiring device to acquire an altitude of an aircraft above ground and a current attitude of the aircraft on which the remote airflow observation device is mounted;
• configuring a route acquiring device to acquire a true traveling direction of the aircraft;
• distributing, by a computing device, the received signal to range bins by time-dividing the received signal;
• removing, by the computing device, a signal derived from a hard target from the received signal;
• searching for, by the computing device, a range bin in which the transmission light falls on ground serving as the hard target on a basis of the received signal distributed to the range bins or on a basis of information including the altitude of the aircraft above the ground and the current attitude of the aircraft acquired by the aircraft information acquiring device;
• excluding, by the computing device, when accumulating a spectrum of a digital signal corresponding to the received signal in each of the range bins, accumulation of the spectrum of a hard-target range bin and accumulation of spectra of one or more range bins farther than the hard-target range bin;
• calculating a correction value corresponding to a difference between the current attitude acquired by the aircraft information acquiring device and the true traveling direction acquired by the route acquiring device;
• and
• outputting, on a basis of the correction value, an electric signal for controlling a beam angle of the optical system by the movable optical mirror or prism so as to correct a relative angular difference between the current attitude and the transmission light and cause the transmission light to observe the same space between pulses.

A non-transitory computer readable medium having stored therein program instructions executable by a computing system to cause the computing system to perform a remote airflow observation method for a remote airflow observation device including a measurement unit configured to radiate transmission light including pulse-form laser light, receive reflected light of the radiated transmission light as reception light, and output a received signal for calculating a wind speed value on a basis of the transmission light and the reception light, the measurement unit including an optical system configured to radiate the transmission light and a movable optical mirror or prism configured to change a path of the transmission light output from the optical system, the method comprising:

• configuring an aircraft information acquiring device to acquire an altitude of an aircraft above ground and a current attitude of the aircraft on which the remote airflow observation device is mounted;
• configuring a route acquiring device to acquire a true traveling direction of the aircraft;
• distributing the received signal to range bins by time-dividing the received signal;
• removing a signal derived from a hard target from the received signal;
• searching for a range bin in which the transmission light falls on ground serving as the hard target on a basis of the received signal distributed to the range bins or on a basis of information including the altitude of the aircraft above the ground and the current attitude of the aircraft acquired by the aircraft information acquiring device;
• excluding, when accumulating a spectrum of a digital signal corresponding to the received signal in each of the range bins, accumulation of the spectrum of a hard-target range bin and accumulation of spectra of one or more range bins farther than the hard-target range bin;
• calculating a correction value corresponding to a difference between the current attitude acquired by the aircraft information acquiring device and the true traveling direction acquired by the route acquiring device;
• and
• outputting, on a basis of the correction value, an electric signal for controlling a beam angle of the optical system by the movable optical mirror or prism so as to correct a relative angular difference between the current attitude and the transmission light and cause the transmission light to observe the same space between pulses.