Micrometer Accuracy Phase Modulated Radar for Distance Measurement and Monitoring

An enhanced accuracy random binary phase modulated radar is proposed. It can be used in high accuracy monitoring in manufacturing. Compared with the traditional high accuracy radar using frequency modulated continuous wave (FMCW), the proposed radar system can be used in a multi-user scenario without occupying more bandwidth. A two-step distance estimation method is introduced to estimate the distance. First, the distance estimation accuracy is narrowed down to a half carrier wavelength by analyzing the envelope of the phase modulated signal. Then the carrier phase information increases the distance accuracy to several micrometers. An equalization method is introduced to solve the I/Q imbalance problem. The proposed radar system is demonstrated at a carrier frequency of 80 GHz with a bandwidth of 2 GHz. The measured distance error was within ±7 µm. In addition, a high measurement repetition rate of 500 kHz was reached which is suitable for real-time monitoring in automatic manufacturing.