 One of limitations of TPQ-37 revealed in tests was that the it was less effective against projectiles with flat trajectory, so it is much more effective against howitzer and mortar rounds than rounds from 130 mm towed field gun M1954 (M-46) and its Chinese derivative Type 59-1.Type 373 radar is designed to improve the capability against rounds with flat trajectory.Another problem revealed in the tests was that the reliability of TPQ-37 is much lower than what was claimed.