Waveform Design with Dual Ramp-Sequence for High-Resolution Range-Velocity FMCW Radar
Frequency modulated continuous wave (FMCW) radar using ramp-sequence is effective method for detecting the range and velocity of a target. For high-resolution range-velocity radar, wide bandwidth and numerous ramps must be generated. In that case, a high-speed sampling rate and a great deal of memory resources are required. Moreover, because fast Fourier Transform (FFT) is used to extract range-velocity profile, computational complexity also increases significantly. Thus, in order to overcome this problem, in this paper, we propose a new waveform with dual ramp-sequence with relatively low modulation slope compared to the conventional waveform. In the first ramp-sequence, the coarse range-profile and fine velocity-profile are extracted. In the second ramp-sequence, both high-resolution range-velocities are obtained, but ambiguous velocity may arise because of diminished maximum detectable-velocity values. This problem may be resolved by combining the results of both ramp-sequences. In this paper, we analyzed the required sampling frequency of an analog-digital converter (ADC) and the amount of data memory required for typical and proposed methods. Moreover, from field programmable gate array (FPGA) based implementation results, we also estimated the processing times. Compared to that of the typical waveform, the reduction ratio for total processing time was 70 %.
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