Signal analysis device, control circuit, storage medium, and signal analysis method

A control circuit for controlling a signal analysis device, wherein the control circuit causes the signal analysis device to:

• modulate a plurality of chirp signals synchronized with one another, and transmit the modulated signals from a plurality of transmission antennas toward an observation area;
• receive, with a plurality of reception antennas, signals transmitted and passed through the observation area, mix the chirp signals with reception signals received with the plurality of reception antennas to generate a plurality of baseband signals, and convert the plurality of baseband signals from analog signals to digital signals;
• and
• convert the plurality of baseband signals that are digital signals resulting from the conversion, from values in a time domain into values in a frequency domain, combine a plurality of values in the frequency domain on a per predetermined frequency range basis to thereby convert the plurality of values in the frequency domain into values smaller in number than the plurality of values in the frequency domain, estimate a coarse reflectance distribution in the observation area, using the smaller number of values, and estimate a reflectance distribution with respect to the observation area, using the coarse reflectance distribution as an initial value of iterative estimation processing, the reflectance distribution being more precise than the coarse reflectance distribution.

A non-transitory storage medium storing a program for controlling a signal analysis device, wherein

• the program causes the signal analysis device to:
• modulate a plurality of chirp signals synchronized with one another, and transmit the modulated signals from a plurality of transmission antennas toward an observation area;
• receive, with a plurality of reception antennas, signals transmitted and passed through the observation area, mix the chirp signals with reception signals received with the plurality of reception antennas to generate a plurality of baseband signals, and convert the plurality of baseband signals from analog signals to digital signals;
• and
• convert the plurality of baseband signals that are digital signals resulting from the conversion, from values in a time domain into values in a frequency domain, combine a plurality of values in the frequency domain on a per predetermined frequency range basis to thereby convert the plurality of values in the frequency domain into values smaller in number than the plurality of values in the frequency domain, estimate a coarse reflectance distribution in the observation area, using the smaller number of values, and estimate a reflectance distribution with respect to the observation area, using the coarse reflectance distribution as an initial value of iterative estimation processing, the reflectance distribution being more precise than the coarse reflectance distribution.

A signal analysis method for use in a signal analysis device, the signal analysis method comprising:

• modulating a plurality of chirp signals synchronized with one another, and transmitting the modulated signals from a plurality of transmission antennas toward an observation area;
• receiving, with a plurality of reception antennas, signals transmitted through the observation area, mixing the chirp signals with reception signals received with the plurality of reception antennas to generate a plurality of baseband signals, and converting the plurality of baseband signals from analog signals to digital signals;
• and
• converting the plurality of baseband signals that are digital signals resulting from the conversion, from values in a time domain into values in a frequency domain, combining a plurality of values in the frequency domain on a per predetermined frequency range basis to thereby convert the plurality of values in the frequency domain into values smaller in number than the plurality of values in the frequency domain, estimating a coarse reflectance distribution in the observation area, using the smaller number of values, and estimating a reflectance distribution with respect to the observation area, using the coarse reflectance distribution as an initial value of iterative estimation processing, the reflectance distribution being more precise than the coarse reflectance distribution.