JPS613364A - Noise diminishing device - Google Patents

Abstract

PURPOSE:To prevent malfunction caused by disturbing signals by recording low-level sound signals after augmenting, reproducing them after lowering a gain by the augmentation at the time of recording, and at the same time, providing a disturbing signal removing filter. CONSTITUTION:As the disturbing signal removing filter 5 is connected to the fron stage of a signal level detector 3, only sound signals are supplied to the detector 3, and malfunction of the noise diminishing device is eliminated. The filter 5 is constituted of a low-pass filter or a band removing filter, and in the case of the band removing filter, a frequency is set to remove only the disturbing wave of specific frequency, and in the case of the low-pas filter, desiged to remove signals of higher frequency including, for instance, the horizontal synchronizing signal frequency of television signals.

Description

[Detailed description of the invention] Industrial use! PI The present invention is directed to home use television (hereinafter referred to as 1-V
It is interlayered in a noise reduction device used in audio No. 15 recording circuits such as TR.

Problems with the configuration of the conventional example Sadachika l', V T RV u';
%J! J 76) Tori II J Tsuka ir+ M+ It is often used to compress and expand audio signals as a means of reducing noise, and often uses noise reduction equipment that uses fJ 'J'.
+C-)-(Sata, 1) For the commonly used TFT change reduction device, when recording a single signal, the low-level signal 5'i is intensified, and the RB f\le (ii It works to hold down the number appropriately, and when re/J1, by changing the operation of the pair when recording, y 'T' is restored and J is strengthened when recording. In order to increase the profit of replaying, the noise level also increases.A typical block diagram of the above-mentioned noise reduction device is shown in FIG.

In FIG. 1, di is I IJ E'j 4:i input NOR terminal, 2nd is a voltage controlled amplifier, and the control voltage [=Thus, the gain of the amplifier changes. 3 is a signal level detector, which detects the audio signal! Create a DC signal according to the novel signal and control the gain of the ti DC signal voltage control amplifier 2.
It is a type of rectifier circuit. 4 is an audio signal output terminal.

When such a conventional noise reduction device is used in a VTR, there is a problem in that the noise reduction device malfunctions due to various interference signals. For example, when recording a television broadcast signal, the audio signal has recently been converted into a multi-audio system with 41 channels (C), so consideration must be given to interference signals of 1 NI and i. Enlightenment is 7j, carrier wave 31
．． 5K II Z Ya), - Country Lt: Pie used to distinguish between live broadcast and stereo broadcast [1 point/Signal 55, 12! iK
Includes l-IZ, etc. This k, a re-recording when receiving the Changichi multiplex broadcast/=? When I, the above-mentioned IJ sub-audio carrier wave and the components of
(In order to reduce noise, there was a problem that the signal 1 novel detector could not detect the true audio signal level.

[1] The present invention prevents malfunction of the signal level detector and maintains reliable operation even during audio multiplex reception.91
Jji the sound reduction device! Take the number 1 J. .

Composition of the Invention The noise reduction device of the present invention amplifies and records a low-level audio signal during recording, and during playback, adjusts the amplification degree of the playback signal amplifier according to the level of the playback signal, and reproduces only the amount enhanced during recording. If the gain of the system is lowered and the noise-reduced audio signal is extracted, the level of the noise-reduced audio signal is detected by the level detector. J,゛ru1,τj
Hand IJ (Characterized by having 11 defenses against 'I'.

Description of examples An embodiment of the present invention will be described above based on FIG. 2.

FIG. 2 is a block diagram of the noise reduction device according to the present invention.
2 is a pressure control amplifier, 3 is a signal level detector, 4 is an audio signal output terminal, and 5 is an interference signal removal filter.

In the present invention, as shown in FIG. 2, since the interference signal removal filter 5 is connected before the signal level detector 3, only the audio signal is supplied to the signal level detector 3, thereby preventing malfunction of the noise reduction device. It disappears.

Note that in the interference signal removal filter 5, the reduced pass filter is constituted by a band removal filter. In the case of a band rejection filter, the frequency is set so that only interference waves of a specific frequency are removed. In the case of a reduced pass filter, for example, the horizontal synchronization signal frequency of a television signal is 1! i, 75K
J'3U may be set to remove high frequency signals including Hz.

Effects of the Invention As explained above, 11 of the present invention? '7 Reduction Le;, Equipment J: During recording, the low-level audio signal is amplified and recorded, and during playback, the amplification degree of the endogenous signal amplifier is controlled according to the level of the playback signal to amplify it during recording. I: The gain of the reproduction system is lowered to take out 1 (sound reduction γ' I tF-sign Y-J), and the reproduction
Since an interference signal removal filter is provided before the signal level detector that detects the signal level, there is no possibility that the frequency characteristics of the i5 voice signal to be recorded will be damaged in any way. ``The r reduction device IS1 can be prevented from operating, and the cylinder is closed without permission.''/>
Is it possible to faithfully record and re-record Prevision's Voice Tayubutsugu etc. in 4M format? It is something that can be done.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional noise reduction device. FIG. 2 is an embodiment of a noise reduction device according to the present invention. - There is a block diagram C shown. 1...Sound 1'4 (ffi @input terminal, 2...Electric control increase*: 4 devices, 3...Signal level detector, 4...
・Name 7" T-output terminal f, 5... Interfering signal removal filter

Claims (1)

[Claims] 1. During recording, the low-level audio signal is amplified and recorded, and during playback, the amplification degree of the playback signal amplifier is controlled according to the level of the playback signal, and the gain of the playback system is lowered by the amount that was strengthened during recording to reduce noise. configured to extract the signal, and
A noise reduction device comprising an interference signal removal filter provided at a stage upstream of a signal level detector that detects the level of the recording/reproducing signal.