SU686147A1

SU686147A1 - Noise suppressor

Info

Publication number: SU686147A1
Application number: SU772495602A
Authority: SU
Inventors: Айзик Рувинович Шварцман
Original assignee: Предприятие П/Я А-3741
Priority date: 1977-06-13
Filing date: 1977-06-13
Publication date: 1979-09-15

Description

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Изобретение относитс к радиотехнике.The invention relates to radio engineering.

Известен шумоподавитель, содержащий последовательно соединенные фильтр шума, подключенный к выходу детектора автоматической регулировки усилени (АРУ) или детектора сигнала , усилитель, детектор, усилитель посто кното тока, и включенный в тракт сигнала ключ, вход управлени которого подключен к выходу усилител посто нного тока 1.A noise suppressor is known that contains a noise filter connected in series to the output of an automatic gain control detector (AGC) or signal detector, amplifier, detector, direct current amplifier, and a switch connected to the signal path, the control input of which is connected to the output of direct current amplifier 1 .

Однако в известном шумоподавителе имеют место шумы в тракте низкой частоты в моменты перепада уровн принимаемого сигнала.However, in the well-known noise suppressor, there are noises in the low-frequency path at the moments of the difference in the received signal level.

Цель изобретени - уменьшение шумов в тракте низкой частоты в моменты скачкообразного изменени уровн входного сигнала.The purpose of the invention is to reduce the noise in the low frequency path at the moments of abrupt changes in the level of the input signal.

Дл этого в шумоподавителе, содержащем последовательно соединенные фильтр шума, подключенный к вь1ходу детектора автоматической регулировки усилени (АРУ), усилитель детектор, усилитель посто нного тока и включенный в тракт сигнала ключ, вход управлени которого подключен к выходу усилител посто нного тока, между выходом детектора АРУ и входом управлени 1слюча включены после до-.For this, in a noise suppressor containing a noise filter connected in series to the detector's automatic gain control (AGC) input, an amplifier detector, a direct current amplifier and a switch connected to the signal path, the control input of which is connected to the output of the direct current amplifier, between the detector output AGC and control input 1switch on after before-.

вательно соединенные дифференцирующа цепь и и дополнительный усилитель.separately connected differentiating circuit; and an additional amplifier.

На чертеже изображена структурна злектрическа схема предлагаемого шумоподавител , вариант, когда шум снимаетс с детектора АРУ.The drawing shows a structural electrical circuit of the proposed noise suppressor, an option where noise is removed from the AGC detector.

Шумоподавитель содержит фильтр 1 шума, детектор 2 АРУ, усилитель 3, детектор 4, усилитель 5 посто нного тока ключ 6, дифференцирующую цепь 7 и дополнительный усилитель 8.The noise suppressor contains a noise filter 1, an AGC detector 2, an amplifier 3, a detector 4, a DC amplifier 5 switch 6, a differentiating circuit 7, and an additional amplifier 8.

Шумоподавитель работает следующим образом .Squelch works as follows.

Шум, спектр которого находитс за пределами спектра сообщени , проходит через фильтр 1, усиливаетс усилителем 3, выпр мл етс детектором 4 и усиливаетс усилителем 5. С The noise, whose spectrum is outside the message spectrum, passes through filter 1, is amplified by amplifier 3, rectified by detector 4 and amplified by amplifier 5.

5 выхода последнего сигнал поступает на вход управлени ключа 6. Если уровень шума ниже некоторого заданного значени , то ключ 6 отперт . В противном случае считаетс , что сигнал корреспондента отсутствует, и ключ 6 запираетс благодар выбранному соответствую1Ш1м образом порогу срабатывани .The 5 outputs of the last signal are fed to the control key input 6. If the noise level is below a certain preset value, then the key 6 is unlocked. Otherwise, it is considered that the signal of the correspondent is absent, and the key 6 is locked due to the threshold selected for the corresponding 1–1 way.

Claims

At the moment when the signal Up disappears, the noise level at the output of filter 1 increases, as a result of which at the output of amplifier 5 a jump of control voltage U occurs. However, this jump objectively lags for some time relative to the moment of loss of signal UQ. A successively connected differentiating chain 7 and an additional amplifier 8 are connected to the input of filter 1; as a result, the delay of this jump is not the cause of a noise click. Since the load of the detector 2 is broadband, the voltage jump at its output occurs almost at the same time as the signal of the correspondent disappears. This jump is transmitted through the differentiating circuit 7 to the additional amplifier 8, which locks key 6 with its output signal. The latter remains in a locked state for some time t, while amplifier 8 maintains its output potential above the threshold from the key of the key 6. After 1 this time, key 6 is unlocked if it is controlled only by the signal of amplifier 8. If time is selected so that by the time it expires the control signal is generated by amplifier 5, then key 6 remains locked and this addict. Thus, the key is locked at the time of the disappearance of the correspondent signal, practically without delay, thereby no noise clicks at the receiver output. At the same time, the advantage of the noise suppressor with the noise channel of the control, which is the stability of its threshold, is preserved. Due to the differentiator capacitor, the additional amplifier only controls the key when the signal level drops. With slow changes in the level, the key controls the noise channel. The proposed device improves the reliability of services in which simplex communication is used. An inventive noise suppressor comprising a noise filter connected in series, connected to the output of an automatic gain control detector (AGC), an amplifier, a detector, a DC amplifier and a switch included in the signal path, the control input of which is connected to the output of a DC amplifier, that, in order to reduce the low frequency path in the low frequency path at the moments of an abrupt change in the input signal level, between the AGC detector input and the key control input are connected in series nennye differentiating circuit and an additional amplifier. Sources, from formash, taken into account during the examination 1. US patent No. 3056086, cl. 325-319, published. 1962.