I have a question regarding the implementation of FMCW radars that seems rather basic to me, but for some reason I am a bit unclear about this.
So I understand that in FMCW radar, transmitter and receiver are constantly, simultaneously transmitting and receiving chirp signals, respectively. The received signal is then multiplied with a copy of the tranmsit signal to deramp/dechirp it and a subsequent FFT on this IF/beat signal yields the range estimates. Now what I am wondering: Is there some sort of synchronization going on between the transmission of the chirp and the deramping in the receiver? Lets say, I start transmitting at a certain time instant, does the receiver side start collecting samples at the exact same moment and multiplies the chirp-copy after the corresponding amount of samples have been collected? As there will be a time delay to, lets say, a point target in the scene, the received chirp and the reference copy would have a certain offset when they are multiplied together. Then, if I understand correct, the receiving signal would be similar to the transmit chirp, but in a sense shifted, with the end of it reappearing in the beginning (coming from the next transmitted and received chirp) I guess to summarize my question: Is the "input buffer" of samples at the receiver side cleared out before the beginning of a new chirp transmission, so that data recording and transmission start at the exact same time? Or is it rather that both transmitting and receiving run freely and a running window of the receive signal is collected and multiplied with the reference? From my understanding, it would matter at what point in time we multiply the reference chirp with the received signal, since this would cause a different delay.
I hope my question makes sense, every tip is appreciated !