SU1356228A1 - Noise suppressor - Google Patents

Abstract

Invention m. used in communications devices for automatic. turning off the pr path and the signal-to-noise ratio is less than the specified one. The purpose of the invention is to reduce the dead zone. The device contains a zero-body 1, a phase synchronization unit 2, a pulse shaper 3, a 4 coincidence unit, a reversible counter 5. Frequency divider 6 is again entered with a controlled coefficient. division, block 7 comparison codes. To change the device threshold, it is enough to write the corresponding numbers in the register 8. Key 9. 2 Il. i O) Fig. /

Description

The invention relates to radio engineering and can be used in communication devices for automatically shutting down a path at a signal-to-noise ratio less than a predetermined one.

The purpose of the invention is to reduce dead zones.

FIG. 1 shows a structural, electrical noise suppressor circuit; in fig. 2 - voltage plots for the operation of the noise suppressor.

The noise suppressor contains a null organ 1, a phase synchronization unit 2, a pulse shaper 3, a coincidence element 4, a reversible counter 5, a frequency divider 6 with a controlled division factor, a code comparison unit 7. In addition, in FIG. 1 shows the register 8 of the threshold and the key 9.

Squelch works as follows.

The mixture of the input signal with noise (FIG. 2a) is fed to the input of the zero-organ 1, which produces short pulses at the moments of transitions of the signal-to-noise mixture through the zero level (Fig. 2b). The pulse sequence from the output of the 1st section of the organ 1 goes to the input of the divider 6 and to the input of the unit 2, which draws a voltage out of it that is synchronous with the clock frequency of the input signal when using telegraph signals or with an intermediate the frequency of the receiver when using other types of signals (Fig 2 in). The synchronous voltage from the output of unit 2 arrives at shaper 3, which forms a sequence of time selection pulses (Fig. 2 d), the centers of which coincide with the moments of abrupt change in the synchronous voltage.

Under the action of noise, the moments of transition of the signal mixture with noise through the zero level experience a time shift relative to the centers of the pulses of the time selection. This shift is greater, the greater the level of noise. By counting the number of pulses, the time shift of which does not exceed the value given by the duration of the pulses of the time selection, and compare this number with the total number of pulses at the output of the zero-body 1,

50

five

5 0 5

0 6

You can evaluate the quality of the input signal.

At the first input of element 4, the time selection pulses come from the output of the imaging unit 3, and the second input receives short pulses from the output of the null organ 1. At the output of element 4, part of the pulses are output from the output of the null organ 1, the time shift of which relative to the centers of the pulses of the time selection does not exceed half the duration of the pulses of the time selection (Fig. 2 d). The pulses from the output of the element 4 are fed to the subtractive input of the reversible counter 5.

The divider 6 divides the frequency of the pulses from the output of the null organ 1 by the number of times corresponding to the control code, i.e. the contents of the reversible counter 5, the Pulses from the output of the divider 6 are fed to the summing input of the reversible counter 5, which increases (decreases) its contents, if the frequency of the pulses at its summing input is greater (less) ,. than on subtractive. Increasing (decreasing) the content of the reversible counter 5 leads to an increase (decrease) in the division ratio of the divider 6 and, consequently, to a decrease (increase) in the frequency of the pulses at the summing input of the reversing counter 5, the process continues until the frequency of the pulses at the inputs of the reversible counter 5 becomes equal. this, with established signal and noise levels, the contents of the reversible counter 5 change only within the limits of the least significant bit. In this case, the contents of the reversible counter 5 can be judged on the signal quality, i.e. about the signal / noise ratio. The greater the signal-to-noise ratio, the smaller the co.

held by the reversing counter 5. I

Reverse Counter Content

5 arrives at the first input of block 7, to the second input of which from register 8 enters a number stored there that corresponds to the threshold of the operation of the noise canceller, until the code at the first input of block 7 is less than the code at the second input; The unit 7 generates a voltage, under the action of which the key 9 is in the closed state and the input signal passes to the output of the noise suppressor. With the pre-code on the first input of the block 7 comparison of the codes on the second input

31356228

block 7, the key 9 is opened and the input signal ceases to arrive at the output of the squelch.

To change the squelch threshold, it is enough to write the corresponding number in register 8.

Claims (1)

Invention Formula A noise suppressor containing a key whose input and output are respectively the input and output of the noise suppressor, a reversible counter connected in series to a null organ whose stroke is connected to the input of the noise suppressor, a phase synchronization unit, a pulse shaper, and a coincidence element whose output are you happy 1Q soo and ccit digits 15 and b go go van 2Q is not Editor L. Povhan. Compiled by N. Melnikov Tehred L. Serdyukova. Proofreader 0. Kravtsov Order 5813/55. Circulation 636 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 is connected to the subtracting input of the reversible counter, and the other input is connected to the output of the null organ, which is due to the fact that, in order to reduce the deadband, a frequency divider with a controlled division factor is introduced into it, the input and output of which are connected respectively, with the output of the zero-organ and the summing input of the reversible counter, and the input of the control of the division factor is connected to the output of the digital code of the reversible counter, and a code comparison unit, the first input of which is connected to the output of the digital code of the reversible counter, the second input is the input of the code of the operation threshold of the noise suppressor, and the output is connected to the input of the key control. phases. 2