Gradient detection algorithm of millimeter wave radar altimeter

The invention discloses a gradient detection algorithm of a millimeter wave radar altimeter. The gradient detection algorithm comprises the following steps: (1) performing waveform design and data acquisition; (2) obtaining distance azimuth data; (3) outputting target point cloud data; (4) calculating the height value of the unmanned aerial vehicle; (5) detecting the gradient of the unmanned aerial vehicle; and (6) outputting a radar result. According to the gradient detection algorithm of the millimeter-wave radar altimeter provided by the invention, accurate height estimation is carried out by using two-dimensional point cloud data of a millimeter-wave radar, and meanwhile, the gradient of a slope is obtained by using multi-point least square fitting; the radar not only can obtain flight height information in real time, but also can detect that the ground is an ascending slope or a descending slope, so that an ascending or descending signal can be fed back to the unmanned aerial vehicle control module in ad