I-Channel FMCW Doppler Radar for Long-Range and High-Velocity Targets

Frequency-modulated continuous-wave (FMCW) radar is known for distance and velocity measurements of close and slow targets, i.e., targets with round-trip delays much shorter and Doppler periods much longer than the chirp repetition period. Solutions for distant targets have been presented for advanced FMCW radar architectures. Here, we analyze how a conventional homodyne I-channel FMCW radar can be used for a multitarget setting without the restrictions of close and slow targets. In a long-range setting, each target appears at two different ranges with opposite velocities. We develop a pure data processing solution to resolve this ambiguity and validate this approach through simulations and experimental results with a long-range moving test target. The work is motivated by our goal to use an off-the-shelf, low-power, and low-cost 24-GHz I-channel FMCW Doppler radar for continuous observation of volcanic eruptions and pyroclastic flows. These targets are moving at high speed and, for safety reasons, can only be observed from a greater distance, requiring the high-velocity long-range solution.