An Analysis of the Effects of Digital Phase Errors on the Performance of a FMCW-Doppler Radar

Peek, K. (2011) An Analysis of the Effects of Digital Phase Errors on the Performance of a FMCW-Doppler Radar.

Abstract:In modern frequency-modulated continuous-wave (FMCW) radars, the transmitter is increasingly being implemented using direct digital chirp synthesis (DDCS), which provides improvements in sweep linearity, stability, precision, agility, and versatility over analog techniques. Its main limitations are errors due to sampling of the modulating signal, phase truncation, and digital-to-analog converter (DAC) quantization, which produce spurious signals due to their deterministic nature. This thesis presents an analysis and simulation of the effect of two sources of digital phase errors – namely, the ‘staircase’ approximation of the linear frequency sweep and phase truncation – on the performance of a FMCW-Doppler transceiver which employs a DDCS in its transmitter. An upper bound for the amplitude of spurious targets resulting from these digital phase errors is established. Further, it is shown that provided the phase errors are periodic with the sweep period, the spurious targets are not offset from the target in Doppler. An algorithm for selecting the digital chirp parameters of a DDCS so as to ensure periodic and phase-continuous sweep transitions is devised. Finally, we investigate parallels of FMCW radar in the optical domain, and consider the fundamental question whether range resolution is fundamentally limited by the bandwidth of a transmitted signal, or its carrier frequency.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics MSc (60436)
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