FIELD: radio engineering.
SUBSTANCE: to input terminal of phase shifter-attenuator with tunable Wien bridge, which includes phasing and control-inertia amplitude of vibrations of the branch, the following is connected in series: the first circuit of resistor and capacitor and the second circuit of capacitor and resistor, which form subsequent branch of Wien bridge, which is connected to non-inverting input of the first operating amplifier. Parallel branch of Wien bridge, which is connected to non-inverting input of the first operating amplifier, is formed with stairs of resistors and capacitors, which is connected to it and to common wire. Inverting input of the first operating amplifier is also connected to its output through negative feedback resistor. Also, the first double potentiometer is connected to input terminal by means of two outputs, and its other outputs are connected to connection points of resistor and capacitor of the first circuit and capacitor and resistor of the second circuit in series branch of Wien bridge. To movable contacts of the first double potentiometre there connected is the second potentiometre the movable contact of which is connected to non-inverting input of the second operating amplifier. Also, there introduced is the third potentiometre the outputs of which are connected to input terminal of phase shifter-attenuator and to common wire and movable contact of the third potentiometre is connected through the first resistor to inverting input of the second operating amplifier; the second operating amplifier is connected through the second resistor from the output to inverting input by means of feedback and its power supply is also connected to movable contact of the third potentiometre; the output of the second operating amplifier is the output of phase shifter-attenuator. Also, to input terminal of phase shifter-attenuator there connected is the fourth potentiometre, the other output of which is input of phase shifter-attenuator, and to its movable contact there connected is measuring unit of effective values.
EFFECT: excluding the dependence of signal amplitude on its frequency and measurement of non-linear distortions introduced with hardware connected to phase shifter-attenuator and distortions introduced with itself.
