 The reason was that when TPQ-37 was deployed in environments with high humidity and high level of rainfall (southern China), high salinity (coastal regions), high altitude (southwestern China), and subjected to daily high temperature differences (northwestern China), malfunctions occurs more frequently.Type 373 radar was designed specifically to improve the reliability against these harsh environmental factors.As Chinese capability in microelectronics matured, an updated version of passive phased array Type 373 radar is developed, designated as SLC-2.