Figure 1.

Basic concept of fast-ramp based 2D range-Doppler FMCW radar: (a) transmitted signal in the frequency-time domain; and (b) beat signal for a single moving target in ramp index domain. Here, $T$ is modulation period, $B$ is bandwidth, $f_H$ is maximum instantaneous carrier frequency, $f_L$ is the lowest carrier frequency, and $K$ is the number of ramps.