Digital signal processing of multi-reflection for short range detection using NRD guide pulse radar front- end at 60 GHz

A pulse radar front-end using an NRD-guide technology was fabricated for a millimeter wave level sensor, and then range finding was performed by using it. Multi-reflection however occurred between a target and a planar antenna due to a pencil beam radiation of our developing planar antenna, so that a precise distance could not be calculated for short range detection. In this paper, an FPGA-based signal processor was devised in order to eliminate such multi-reflection. Continuous sampling method was employed to reduce experimental errors, which were investigated from the viewpoint of difference of a period between a modulated pulse train and a continuous sampling clock. The error of range finding was successfully measured to be less than 12 cm for the distance range from 2 m to 20 m under the multi-reflection environment. It was improved compared with that of a signal processor without the continuous sampling method.