This is a pulsed system - we send out 1us wide chirped signals, then listen for their returns before sending out the next signal. So - we know how far away a return is, but the tricky bit is knowing which direction it came from, since our beam pattern is so wide.

We do use a chirped signal in order to improve vertical resolution - convolving the outgoing pulse with the returned trace gives us the equivalent resolution of a ~80ns pulse, but with more power.