Abstract: Under the condition of CAT (Computer aided test), the test data about electro-hydraulic servo valve frequency response characteristic is processed with the discrete way. The disposal brings some errors to the test results. The magnitude of error is connected with the degree of discreteness. By analyzing the data’s relation between the degree of discrete and the magnitude of error in detail , some methods how to increase the test precision of servo valve frequency response characteristic are given, and the theory analyses in this article are verified by the tests.

Key words: CAT, Data process, Error analysis, Phase frequency characteristics, Servo valve