How is the target velocity computed or used in the PIR format

[luckyyf0517]

Hello, the last velocity dimension in the PIR array was set to zeros, and the comments in code said that it 'will be calculated later by calculating the difference between two frames'. In signal generation, the velocity dimension was neither computed nor used. Alternatively, interpolation is used to obtain the positions of the reflection points in each chirp subframe, which are shifted in time to simulate the Doppler effect.

Do I understand correctly? Then I wondered, since the velocity dimension is not being used, is the diffusion module actually adjusting the position and intensity of the reflection point of each radar ray?