METHOD FOR JOINT MEASUREMENT OF FREQUENCY, PHASE AND INITIAL PHASE OF HARMONIC SIGNAL Russian patent published in 2013 - IPC G01R23/00 

FIELD: measurement equipment.

SUBSTANCE: method includes digitisation of an analogue signal, representation of its fragment with three digital codes S₁, S₂, S₃, generated at the moments of time t₁, t₂, t₃ and used to calculate the signal frequency f according to the formula $$f=\frac{1}{2\pi \tau }\arccos \frac{S_1+S_3}{2S_2},$$ where τ - digitisation interval. At the same time the signal fragment and the appropriate three codes are selected so that the code S₂ is not zero. In process of frequency variation the same codes are used to calculate the amplitude U, the phase φ and the initial phase of the signal φ₀ in accordance with the following expressions: $$U=2\left|S_2\right|\sqrt{\frac{\left(S_2^2-S_1{S}_3\right)}{\left[4S_2^2-{\left(S_1+S_3\right)}^2\right]}},$$ $$\phi =\arccos \left(\frac{S_2}{U}\right)$$ and φ₀=φ-2πft₂, where the phase φ corresponds to the moment of time t₂.

EFFECT: accelerated measurements.