Specific features of two-frequency testing

The paper analyzes the two-frequency testing technique in terms of the vector sum of the signals at the main and auxiliary frequencies converted to signals of one frequency. The use of signals at the auxiliary frequency in suppressing an interfering factor is discussed in the cases when only the interfering factor is varied and when both the interfering and measured factors change concurrently. Amplification of a measured signal by this method is also considered. The efficiency of the technique used in these tasks has been estimated.