SU1293854A1 - Loudspeaking device with audio control - Google Patents

Abstract

The invention relates to telecommunications. The purpose of the invention is to improve noise immunity. The device contains a transmission amplifier 1, a switch 2, an amplifier-separation unit 3, a signal analyzer 4, three delay 5, 7 and 12 rectifiers, a comparator 6, a reception amplifier 8, a notch filter unit (BRF) 9, a bandpass filter unit (FFT) 10, 11 and El-13. The goal is achieved by introducing BRF-9, FFT-10 and El-13, which ensure the undistorted transmission of speech sounds when there is a low-frequency acoustic noise at the reception and transmission premises. 1 il. S (O and-i.: O 00 eo l

Description

The invention relates to a technique of electrical communication and can be applied in voice communication systems, in particular with a vocoder voice converter.

The purpose of the invention is to improve noise immunity.

The drawing shows an electrical circuit diagram of a voice-controlled loudspeaker device.

The voice-controlled loudspeaker device contains a transmission amplifier 1, a switch 2, an amplifier / divider unit 3, a signal analyzer 4, a first rectifier with a delay of 5, a comparator 6, a second rectifier with a delay of 7, a receive amplifier 8, a notch filter unit 9, a bandpass filter unit 10, an amplifier 11, a third rectifier with a delay of 12, And 13.

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The voice-controlled loudspeaker operates as follows.

If the transmission is not conducted, then the inputs of the key 2 and the amplifier-divider unit 3 receive the voltage developed by the microphone from acoustic noise. If the spectrum of the noise and its amplitude distribution are different from the corresponding characteristics of natural speech, then And 13 does not work, the first potential of the comparator 6 remains zero potential and the key 2 remains locked.

With the beginning of the transfer to the input key

2 A voltage developed by a microphone from natural speech is supplied through an amplifier / divider unit.

3 enters the parallel-connected inputs of the signal analyzer 4 and the bandpass filter unit 10. Through the signal analyzer 4, the voltage components of the speech signal in the band up to 150 Hz (when using a wideband telephone signal) or in the band up to 300 Hz (using the PM channel) and frequencies, respectively, of 7000 or 3400 Hz through the first rectifier with a delay of 5 is fed to the second input of the element 13. At the first input of the element

And, 13 is the voltage developed by the microphone from natural speech and passing through the bandpass filter unit 10, amplifier 11 ,. third in

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the delayed delay 12. As a result of this Tc-ate, a second control voltage is applied to the second input of the comparator 6, under the action of which a voltage appears at the output of the comparator 6, which opens the key 2 and the voltage of the voice signal. This ensures undistorted transmission of speech sounds.

The potential for the second (unlocking) input of the comparator 6 comes only when the speech signal contains both signs of natural speech, namely: its component is in the frequency bands up to 150 (300) Hz and over 7000 (3400) Hz, and in the frequency bands, for example 2800-3200 Hz and 4000-4800 Hz. With a delay of 12 delays in the third rectifier of the order of several milliseconds, short-term dips between individual speech signals have little effect on the potential value at the first input of the I 13 element.

When transmitting from the telephone set by the subscriber of the peripheral point of communication, the voltage of the speech signal is fed to the input of the block of notch filters 9 and from its output to the input of the receiving amplifier 8. From one of the outputs of this amplifier, the voltage goes through the second rectifier (locking) the input of the comparator 6. The comparator 6 remains locked and from its output the zero potential is fed to the input of the key 2, which also remains locked. Suppose that communication is carried out through a broadband telephone channel with a band of 150-7000 Hz. After passing through the notch filter block 9, the components in the frequency band, for example, 2800-3200 Hz and 4000-4800 Hz, are also suppressed in the speech signal. Thus, the speech signal reproduced by the loudspeaker does not contain components up to 150 Hz, more than 7000 Hz, and also in the aforementioned delay bands of the notch filter block 9. Therefore, after passing such a signal through the amplifier-dividing block 3, it is delayed by chains units from blocks 4 and 5, as well as from blocks 10-12. As a result

at the two inputs of the element And 13 there are potentials close to zero. Accordingly, the zero potential is maintained at the second (unlocking) input of the comparator 6, whereby the key 2 remains locked. Suppose that in the room in which the reception is carried out, low-frequency acoustic noise takes place, the components of which through a signal analyzer 4 and the first rectifier with a delay of 5 act on the second input of element 13. As in the first input of element 13, if the potential is zero, the voltage at the second (unlocking) input of the comparator 6 will also remain zero and the key 2 will be locked. A similar picture takes place when there is low-frequency acoustic noise in the reception and transmission premises, or if there are no components in the frequency bands of 2,800–3,200 Hz and 4,000–4,800 Hz. Since the probability that the acoustic noise will satisfy all the characteristics of the level and spectrum of natural speech is small, noise immunity increases in this speaker device, controlled by voice.

Editor N. Gorvat Order 398/60

Compiled by V. Grachev

Tehred A. Kravchuk Proofreader A. Zimokosov

Circulation 639 Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Design, 4.

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Claims (1)

A voice-controlled loudspeaker device comprising a transmission amplifier, the output of which is connected to the first key input and the input of the amplifier / divider unit, the output of which is connected to the input of the signal analyzer, the output of which is connected to the input of the first rectifier with delay, and also a comparator , the first input of which is connected to the output of the second rectifier with a delay, the input of which is connected to the output of the amplifier npJiieMa, the output of the comparator is connected to the second input of the key, characterized in that nor noise immunity, a block of filter regulators was introduced, as well as; a series of band-pass filters connected in series, an amplifier, a third rectifier with a delay and an And element, the second input of which is connected to the output of the first rectifier with a delay, and an output of the And element , the input of the bandpass filter unit is connected to the output of the amplifier-divider unit, and the output of the rejector filter unit is connected to the input of the receive amplifier.