SU446035A1 - Device for measuring amplitude and phase frequency characteristics of elements and automatic control systems - Google Patents

Description

one

The invention relates to the field of automation and can be used in the design, testing and operation of elements and automatic control systems.

A device for measuring amplitude and phase frequency characteristics (AFCh) of elements and automatic control systems is known, comprising a frequency controlled oscillator coupled to an object under investigation, an amplitude adjustment channel comprising a series-connected multiplication unit, a synchronous detector, an integrator and an indicator, a frequency adjustment channel phases, including a series-connected synchronous detector, integrator and indicator, both channels connected to frequency adjustable the generator of sinusoidal oscillations through an adjustable phase shifter, the first output of the phase shifter is connected to one of the inputs of the synchronous phase detector, the first input of the phase shifter is connected to the output of the frequency-controlled generator of sinusoidal oscillations, its second input is connected to the output of the integrator of the phase adjustment channel, and the output of the integrator of the amplitude adjustment channel is connected to one of the inputs of the multiplication unit. The disadvantage of the known device

is that the selection of the average component of the signal of synchronous detectors is carried out by integrating their output signals strictly over a period. This leads to a decrease in speed and accuracy of the device.

The purpose of the invention is to increase the speed and accuracy of the device. This is achieved by the fact that the device contains an adder, one input of which is connected with the output of the object under study, the other input with the input of the synchronous detector of the amplitude adjustment channel, the output is connected to the inputs of both synchronous detectors, and the second input of the block

multiplication is connected to the second output of the phase shifter.

The drawing shows a diagram of the device.

It contains a sinusoidal generator 1

oscillations whose frequency can vary, the object under study 2, the tunable phase shifter 3, the adder 4 to two inputs, the amplitude adjustment channel 5 and the phase adjustment channel 6. The output of the generator 1 is connected to the input of the object under study 2

and a phase shifter 3, and the output of the object is connected to one of the inputs of the adder 4.

The amplitude adjustment channel 5 includes an multiplication unit 7, a synchronous detector 8 amplitude, an integrator 9 and an amplitude indicator 10. One input of the multiplication unit

7 is connected to the sinus output of the phase shifter 3, the second is connected by ci to the output of the integrator 9 and the input of the amplitude indicator 10, and its output is connected to the free input of the adder 4 and to one of the inputs of the synchronous detector 8, the second input of which is connected to the output of the adder 4, and output-. to the integrator input 9.

The phase adjustment channel 6 includes a synchronous phase detector 11, an integrator 12 and a phase 13 indicator. Moreover, one input of detector II is connected to the cosine output of the phase shifter 3, the second to the output of the adder 4, and the output to the input of the integrator 12, the output of which in turn connected simultaneously to the input of the phase indicator 13 and to the control input of the phase shifter 3.

The device works as follows.

The signal from the output of generator 1 is fed to the object under study and simultaneously to the input of the phase shifter 3. From the output of the phase shifter 3, two signals are taken that differ by 90 ° phase. One of these signals, the passage through the multiplication unit 7, goes on simultaneously to one of the two inputs of the adder 4 and to the synchronous detector 8 of the amplitude adjustment channel 5. The other signal of the phase shifter 3 is shifted by 90 in phase with respect to the first one and is fed to the detector 11 of the channel 6 of the phase adjustment. The second input of the adder 4 also supplies a signal from the output of the object under study 2. The adder 4 performs the operation of subtracting these two signals, and the signal from multiplication unit 7 acts as a compensation signal. From the output of the adder 4, the signal error compensation is supplied simultaneously to the synchronous detector 8 amplitude and synchronous detector 11 phase. The spectral composition of the output signals of synchronous detectors 8 and I is quite complicated, however, the main part of the spectrum of the signal of the synchronous detector 8 amplitude contains information about the amplitude compensation error, and the main part of the spectrum of the signal of the phase And phase detector.

The signal from the output of the amplitude detector 8 goes to the integrator 9, the output of which is fed simultaneously to the multiplication unit 7, thereby forming a closed tracking system of the amplitude channel 5, and to the amplitude indicator 10, because after zeroing the compensation error, the output signal of the integrator 9 is proportional to the ratio the output and input amplitudes of oscillations of the object under study 2. The output signal of the phase detector 11 is fed to the integrator 12, the output of which is fed simultaneously to the phase shifter 3, forming

thus, the closed tracking system of the channel 6 phase, and the phase indicator 13. The output signal of the integrator 12 is proportional to the phase shift of the output and input signals of the object 2.

Due to the operation of the following systems of channels 5 and 6 of amplitude and phase, the average component signals of synchronous detectors 8 and 11 are zeroed out. The following systems are closed in amplitude and phase through changes in the amplitude and phase of the compensation signal. Upon the occurrence of equality of the compensation signal from the output of the object under study, their difference, i.e.

the compensation error at the output of the device to be summed0 is zero, which in turn causes a decrease to zero signals at the outputs of synchronous detectors.

Testing the amplitude and phase occurs simultaneously, which significantly increases the speed of the device, and the use of a combination of the compensation method with synchronous detection increases the measurement accuracy.

Subject invention

A device for measuring amplitude and

phase frequency characteristics of elements and automatic control systems, containing a frequency-controlled sinusoidal oscillator connected to the object under study, an amplitude adjustment channel, including a series-connected multiplication unit, a synchronous detector, an integrator and an indicator, a phase adjustment channel, including a series-connected synchronous detector, integrator and an indicator, both channels connected to a frequency-controlled generator of sinusoidal oscillations through regulating first phase shifter, a first phase shifter output is connected to one of the synchronous phase detector inputs, the first input of the phase shifter coupled to the output of the controlled frequency generator of sinusoidal oscillation, a second input connected to the output of phase locked channel integrator

and the output of the amplitude adjustment integrator channel is connected to one of the inputs of the multiplication unit, characterized in that, in order to increase the speed and accuracy of the device, it contains an adder,

one input of which is connected with the output of the object under study, the other input - with the input of the synchronous detector of the amplitude adjustment channel, the output is connected to the inputs of both synchronous detectors, and the second input

the multiplication unit is connected to the second output of the phase shifter.