I have gone through the mmwave FMCW radar training material and have the problem understanding the concept mentioned at P.38 and P.58 (they are similar concepts)
At P.38, It is mentioned from the material or video that, "The value at the peak has phasor components from both objects. Hence previous approach will not work." and I just don't understand this statement. I try to describe what I am thinking below:
At P.37 where there is only one object in the scenario, and we have phase of the object from two chirps, and thus we can calculate the phase rotating speed (since the time between two chirps is known), and thus calculate the corresponding radial velocity of the object. I have no problem understanding this page.
Question 1: At P.38, two objects in the same range. If we know the independent phasor components from both objects, why can't we use the same method at P.37 to find the corresponding radial velocity for the objects?
(I am not sure if we have the independent phasor components actually. Here is my guess: for each object, we can draw the range-FFT (at the specific range bin) as a vector in complex plane with amplitude and phase axis. and if we have two objects, we might have the sum of two vectors only, instead of the individual vector.
Question 2: follow up of question 1. If there are some reason that this method do not work for two objects in the same range, how come transmit more chirps would solve the problem? With more chirps, for each chrip the value at the peak still has phasor components from both objects, it seems to me that it does not change anything, except providing some sample for doing FFT.
Thanks!
