A Novel Long-Distance Measurement Method Based on Secondary Radar

In this paper we present a novel method for high precision long-distance measurement based on secondary radar. In this method, we employ two transceivers unit to work in an acknowledged mode as secondary radar system to achieve the round-trip time-of-flight (RTTOF), and introduce a system group delay (SGD) to estimate the time of the measurement signal through the system circuit. The real RTTOF related to the measured distance is acquired by deducting the SGD in the RTTOF. The prototype operates within the 433MHz ISM-Band. The results show the method has a good preference in long distance measurement at 1 km and the measurement principle is robust towards multi-path effect and target identification.