SU832578A1 - Noise suppressing device - Google Patents

Description

; 54) DEVICE. FOR PRESSING ILVMA

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This invention relates to instrumentation engineering and can be used in noise reduction.

A device for noise suppression is known, comprising a microphone, an audio amplifier, a selective filter, an addition circuit, phase shifters, a delay line, a power amplifier, and a loudspeaker 1.

The disadvantages of this device include the lack of automation of noise suppression and the relatively low degree of its suppression.

The closest to the offerable is a noise suppression device containing a connected preamplifier, a first filter, a phase shifter, an amplitude controller, a power amplifier and a loudspeaker) and a second filter, four AND schemes, an increment sign control unit, an addition circuit, a line delay, modulator, pulse signal generator: §, rectifier and microphone 123.

The disadvantage of this device is not enough high degree of noise suppression, the amplitude and phase of the spectral components of which

changes in time according to a random law.

The purpose of the invention is to increase the degree of noise suppression whose amplitude and phase of the spectral components of which changes in accordance with the Iy law.

The goal is achieved by the fact that the device for suppressing

0 noise, containing a sensor connected in series, a preamplifier, a first filter, a phase shifter, an amplitude controller, a power amplifier and a loudspeaker, and

5 also a second filter, four AND schemes, a block of control of the increment sign of the parameter being corrected, an addition circuit — a delay line, a modulator, a pulse signal generator, a rectifier and a microphone, is equipped with a block for selecting the parameter being corrected, a display unit for at least two detectors, the second input of the phase shifter is connected to the output of the first And circuit, its third input is connected to the output of the second And circuit, the second input of the amplitude controller is connected to the output of the third And circuit, the third, its input is connected to the output of the fourth And circuit, the first in moves first and

0

the third circuit And connected to the first output of the control unit of the increment sign of the parameter being corrected, the second input of which is connected to the first input of the second and fourth And diagrams, the second inputs of the first and second And diagrams are connected to the first output of the selection block of the corrected parameter, BTOJ output of which is connected to the second inputs of the third and fourth circuits And, the input of the block for selecting the parameter to be corrected is connected to the output of the minimum indication block, the first input of which is connected to the input of the block for monitoring the sign of the increment of the corrected pair With the output of the addition circuit, the first input of which is connected to the second input of the minimum indication unit, and through the delay line and the first detector to the modulator output and simultaneously through the second detector to the second input of the addition circuit, the first input of the modulator is connected to pulse signal generator, and its second input through the rectifier and the second filter is connected to the microphone.

The drawing shows a block diagram of the proposed device.

The device contains a sensor 1, for example, a piezoelectric type, the output of which is connected through the preamplifier 2 and the first filter 3 is connected to the first input of the phase shifter 4, the output of which is connected to the first input of the amplitude regulator 5, and the output of the amplitude regulator 5 is connected via power amplifier 6 loudspeaker 7, the second input of the phase shifter 4 is connected to the output of the first circuit And 8, the third input of the phase shifter 4 is connected to the output of the second circuit And 9, the second input of the amplitude adjuster 5 with the output of the third circuit And 10, the third input of the regulator 5 The slits are connected to the output of the fourth circuit AND 11, while the first inputs of the first 8 and third 10 circuits are connected to the first output of the block 12 of the control of the increment sign of the parameter being corrected, the second output of which is connected to the first inputs of the second 9 .and the fourth 11 And circuits, the second inputs the first 8 and second 9 circuits And are connected to the first output of the block 13 for selecting the parameter being corrected, the second output of which is connected to the second inputs. The third 10 and fourth 11 circuits are And, the input of the block for selecting the parameter to be corrected is connected to the output of the minimum display block 14 ma, the first input of which is connected to the input of the unit 12 of the control of the increment sign and corrected parameter and with the output of the adding circuit 15, the first input of which is connected to the second input of the minimum indication unit 14 and, through the delay line 16 and the first detector 17, to the output of the module Torah 18 ,. In this case, the output of the modulator 18 through, the second detector 19 is also connected to

the second input of the addition circuit 15, the first input of the modulator 18 is connected to the pulse signal generator 20, the second input of the modulator 18 via the rectifier 21, the second filter 22 is connected to the microphone 23.

The device works as follows.

A compensating signal, the spectral composition of which is identical to the spectral composition of the suppressed noise, is formed by a sensor 1, for example, a piezoelectric element or a microphone.

The signal from the output of sensor 1 through the pre-amplifier 2, the first filter 3 is fed to the first input of the phase shifter 4, from the output of which the signal is then fed to the first input of the amplitude regulator 5. From the output of the amplitude controller 5, the signal through the power amplifier 6 is fed to the loudspeaker 7. The loudspeaker 7 excites sound waves that compensate for the sound field of a noise source not indicated in the drawing. Noise reduction is achieved by automatic amplitude and phase adjustment of the compensating signal.

At the initial moment of operation of the device, positive signal levels (constant signal) are set at the first output of the control unit 12 of the increment sign of the parameter being corrected and the first output of the parameter selectable parameter block 13, which allows generating the signal level at the output of the first AND 8 circuit. At the third input of the phase shifter 4, as well as at the second and third inputs of the amplitude adjuster 5, there are no resolving signal levels. The formation of the permitting level at the corresponding input of the phase shifter 4 and the amplitude adjuster 5 allows the phase or amplitude of the compensating signal to be smoothly changed in one direction or another.

The formation of the resolving signal level at the second input of the phase shifter 4 and the amplitude controller allows the phase and amplitude of the compensating signal to change in a certain direction, respectively, conventionally we call this direction positive. The formation of the resolution level at the third input of the phase shifter 4 and the controller 5 allows the phase and amplitude of the compensating signal to be changed in the opposite, negative, direction.

Claims (2)

1. USSR author's certificate 590807, cl. Q 10 K 11/00, 1977. 2. Ken ity Kido, Senehi Onoda. Automat I with Control of Acoustic Noise Emitted from power Transformer by Synthetic Directivity JSei Repts. Reo.nst.:Tohokyc Univ ,, B; Elec. 5 Commun. 1971, 23, 3-4, 97, -llG (prototype).