Development and Evaluation of the Universal DRFM-based Simulator of Radar Targets

This article is devoted to the implementation of a simulator of reflected signals for altimeters and radars with various types of probing signals. The discussed method for generating a signal at a carrier frequency is based on digital radio frequency memory (DRFM) technology. But here, to make a smoothly change in the variable propagation range (and signal delay), two different clock frequencies are synthesized to digitize and restore the signal. The difference between these frequencies allows one to reproduce the Doppler frequency shift effect, which is important for the correct modeling of the time-frequency structure of the reflected electromagnetic wave. In addition, to expand the simulator's capabilities, a quadrature multiplier and a digital shaping filter are additionally applied to reproduce short ranges and reflections from surfaces. To improve the quality, the quadrature signal is created using the Hilbert transform of a fast single-channel ADC-converted signal. The main stages of digital signal processing (DSP) are performed by FPGA, which controls the simulator parameters in real time.