KR960009858Y1 - A circuit for preventing stereo mis-action - Google Patents

Abstract

No content.

Description

Stereo malfunction prevention circuit during mono broadcasting reception

1 is a sound processing circuit diagram of a conventional TV.

FIG. 2 is a pilot signal waveform diagram detected by the pilot signal detector of FIG.

FIG. 3 is an explanatory diagram for explaining a voice processing procedure of the voice processing shown in FIG.

4 is a waveform diagram for explaining the case where the pilot signal detector of FIG. 1 discriminates noise components in stereo.

5 is a stereo malfunction prevention circuit when the mono broadcast reception of the present invention.

* Explanation of symbols for main parts of the drawings

100: voice intermediate wave detection unit 101, 102: first and second de-emphasis unit

103: pilot signal detector 104: voice processor

105: noise canceling unit

The present invention relates to a stereo malfunction prevention circuit when receiving a mono broadcast in a TV. In particular, a noise component in mono sound is detected by incorrect detection of a noise component in a NICAM mono broadcast or a mono broadcast by stereo or dual broadcast. The present invention relates to a stereo malfunction prevention circuit when receiving a mono broadcast to prevent noise from being introduced.

The conventional TV's voice processing circuit includes a voice intermediate frequency detector 100 for detecting a main frequency and a sub voice intermediate frequency at a received high frequency, as shown in FIG. The first de-emphasis unit 101 for outputting the intermediate frequency of the high frequency emphasized main voice (5.5MHZ) obtained in (100) to a predetermined level and outputting the high frequency emphasized sub-voice obtained in the voice intermediate frequency detector 100 (5.74). Detects the pilot signal at the intermediate frequency of the high-definition sub-negative (5.74MHZ) obtained by the second de-emphasis unit 102 for outputting the intermediate frequency of MHZ by a predetermined level and outputting the negative intermediate frequency detector 100. The voice signal processing unit 104 for processing the voices obtained by the first and second de-emphasis units 101 and 102 according to the pilot signal detector 103 and the signal output from the pilot signal detector 103. It consisted of

In this case, the voice processor 104 may include a pilot signal discrimination unit 104a for determining a pilot signal obtained by the pilot signal detector 103 and the first and second signals according to the signal obtained by the pilot signal discrimination unit 104a. It is composed of a voice matrix unit 104b for matrixing and processing the voice signals obtained from the de-emphasis unit 101 and 102.

The operation of the conventional voice processing circuit configured as described above will be described in detail with reference to FIGS. 2 and 3.

In the broadcast signal received through the tuner (not shown in the drawing), the voice intermediate frequency detector 100 detects the voice intermediate frequency.

In this case, the voice intermediate frequency 100 separates and splits a voice frequency into a main voice (5.5 MHZ) and a sub voice (5.74 MHZ) when receiving a stereo or multiple broadcast, and outputs the respective output ports AF1 and AF2. ) To separate output.

First, the voice intermediate frequency of the main voice (5.5MHZ) output from the output port AF1 decreases the high frequency component emphasized at the front end in the first de-emphasis unit 101, which is characterized by the following equation (1). Degrades.

The voice intermediate frequency whose frequency characteristics are deteriorated in this way is an AC component through the coupling capacitor C4 and is input to the coat P1 of the voice matrix number 104b in the voice processing unit 104.

In addition, the voice intermediate frequency of the negative voice (5.74MHZ) output from the output pose AF2 lowers the high frequency component emphasized at the front end in the second de-emphasis unit 102, which is deteriorated in frequency characteristics by the following equation (2). do.

In this way, the voice intermediate frequency of which the frequency characteristic is deteriorated becomes an AC component through the coupling capacitor C5 and is input to the port P2 of the voice matrix unit 104b in the voice processing unit 104.

On the other hand, the intermediate frequency of the sub-negative (5.74MHZ) output from the output port AF2 of the voice intermediate frequency detector 100 is a pilot signal detector 103 through a resistor (R3) and a capacitor (C3) which is a high frequency filter ) Is entered.

Accordingly, the pilot signal detector 103 detects the envelope signal of the amplitude modulated (AMPLITIDE MODUALTION) by 54.68KHZ carrier component at the input frequency, and shows (a) and (b) shown in FIG. We detect a pilot signal of 117.5HZ, 274.1HZ.

The detected pilot signal is input to the pilot signal discrimination unit 104a in the speech processing unit 104.

Accordingly, the pilot signal determining unit 104a determines that the received voice signal is stereo when the pilot signal inputted as shown in (a) is 117.5HZ, and discriminates by voice multiplication when it is 274.1HZ as shown in (b). do.

When the voice signal is determined as described above, a signal corresponding thereto is applied to the input port P3 of the voice matrix unit 104b.

When the voice discrimination signal is input through the input port P3, the voice matrix unit 104b combines the voice signals input to the ports P1 and P2 and outputs them through the channel R and the channel L. The explanation is as follows.

First, in stereo, the audio signal L + R / 2 component input to the port P1 becomes the L + R component 3-2 through the multiplier 3-1 as shown in FIG. The 2R component, which is the audio signal input to P2, becomes an R component through the 1/2 multiplier (3-4) and is output to the R channel.

On the other hand, in monophony, the L + R / 2 component, which is the audio signal input to the port P1, becomes the L + R component 3-2 through the multiplier 3-1 and is output to the L channel.

In the figure of FIG. 3, the switch 3-6 is switched in accordance with the output value of the pilot signal discriminating unit 104a input to the input port P3.

However, these conventional voice processing circuits operate normally during stereo broadcasting or multicasting. However, when monocasting in NICAM broadcasting, noise components are incorrectly detected in stereo or dual broadcasting, and noise components are introduced into the mono voice. There was a problem that occurred.

For example, in the case of mono broadcasting in Nikcam broadcasting, only the main voice of 5.5 MHZ is vertical, but the Nikam carrier component is loaded at 5.85 MHZ, resulting in a bandwidth of 5.85 MHZ ± 250 KHZ.

As a result, the Nikcam carrier component is detected in the 5.74 MHZ negative speech circuit in the intermediate frequency detector, and this is a noise component, and the pilot signal detector detects the stereo signal of 117.5 HZ as shown in FIG.

In this way, if the noise component is incorrectly detected in the stereo of 117.5HZ by the pilot signal detector, the pilot signal discriminator may be identified as stereo. Since the noise is matrixed and output, the speaker generates instantaneous noise.

In addition, when noise is introduced into the main voice even during pure mono broadcasting, it is also identified as stereo by the false detection as described above, and thus instantaneous noise is generated in the speaker as described above.

Therefore, an object of the present invention is to detect a stereo component in a stereo broadcast or a mono broadcast by receiving a stereo component or multi-broadcast, so that a noise component is introduced into the mono sound to prevent noise from occurring. In providing.

This is achieved by high-pass filtering a negative voice intermediate frequency of the object of the present invention and switching according to the filtered frequency to remove noise applied to a pilot signal detector at a later stage. When described in detail based on the accompanying drawings as follows.

5 is a schematic diagram of a mono-broadcast stereo malfunction prevention circuit of the present invention. As shown in FIG. 5, a voice intermediate frequency detector 100 for detecting a voice intermediate frequency of a main voice and a negative voice at a received high frequency and the voice intermediate frequency are shown. The first de-emphasis unit 101 for lowering and outputting the intermediate frequency of the high frequency emphasized main voice (5.5MHZ) obtained by the detector 100 to a predetermined level, and the high frequency emphasized section obtained by the voice intermediate frequency detector 100. The second de-emphasis unit 102 for lowering and outputting the intermediate frequency of the voice (5.74MHZ) to a predetermined level and the negative frequency obtained by the voice intermediate frequency detector 100 are high-pass filtered and the filtered frequency. A noise canceling unit 105 for removing noise of the sub-negative intermediate frequency and a pie signal for detecting a pilot signal at a main audio intermediate frequency output from the voice intermediate frequency detector 100 The first signal according to the output signal from the bit detection unit 103, the pilot signal detection section 103. The audio processing unit 104 processes the audio obtained by the second de-emphasis unit 101 (102).

Herein, the voice processing unit 104 includes the pilot signal discriminating unit 104a obtained by the pilot signal detecting unit 103 and the first and second de-emphasis unit 101 according to the signals obtained by the pilot signal discriminating unit 104a. Speech matrix obtained from the speech signal 102 is composed of a speech matrix portion 104 for matrixing and processing the speech signal.

The same parts as in the prior art are given the same reference numerals.

Referring to the operation and effect of the stereo malfunction prevention circuit when receiving the present invention mono broadcasting configured as described in detail as follows.

In the broadcast signal received through the tuner (not shown), the voice intermediate frequency detector 100 detects the voice intermediate frequency.

Here, the voice intermediate frequency detector 100 separates and detects the voice intermediate frequency into the main voice (5.5 MHZ) and the sub voice (5.74 MHZ) during stereo or multicast reception, and detects each of the output ports AF1 and AF2. Through separate output.

First, the voice intermediate frequency of the main voice (5.5MHZ) output from the output port AF1 lowers the high frequency component emphasized at the front end in the first de-emphasis unit 101, which is represented by the following equation (3). Lowers.

In this way, the voice intermediate frequency of which the frequency characteristic is deteriorated becomes an AC component through the coupling capacitor C4 and is input to the port P1 of the voice matrix unit 10b in the voice processing unit 104.

In addition, the voice intermediate frequency of the sub-negative (5.74MHZ) output from the output port AF2 lowers the high frequency component emphasized at the front end in the second de-emphasis unit 102, which is characterized by the following equation (4). Lowers.

The inter-voice frequency in which the frequency characteristic is deteriorated in this way is an AC component through the coupling capacitor C5 and is input to the port P2 of the voice matrix unit 104b in the voice processing unit 104.

On the other hand, the intermediate frequency of the negative note (5.74MHZ) output from the pull port (AF2) of the voice intermediate frequency detector 100 is filtered through a resistor (R3), a capacitor (C3), which is a high-frequency filter pilot signal detector It is input to 103.

Accordingly, the pilot signal detector 103 detects a pilot signal that is amplitude-modulated (AMPLITUDE MODUALTION) with a carrier component of 54.68 KHZ at an input frequency.

The detected pilot signal is input to the pilot signal discriminating unit 104a in the speech processing unit 104.

Accordingly, when the detected pilot signal is 117.5KHZ, the pilot signal discrimination unit 104a determines that the received voice signal is stereo. The voice matrix unit 104 is inputted through the input port P3 of the unit 104.

The voice matrix unit 104 outputs the main voice and the sub-audio input to the ports P1 and P2 according to the pilot signal discrimination signal input in this manner and outputs them to the R channel and the L channel.

On the other hand, if the voice intermediate frequency detector 100 detects the negative sound according to the inflow of noise during the Nikammon broadcast or broadcast, the detected intermediate frequency is the high frequency filter in the noise canceling unit 105 (C7). After filtering with a resistor (R5), it is applied to the base of the switching element (Q1).

At this time, when noise is introduced into the negative negative frequency, the switching element Q1 is conducted by the intermediate frequency into which the noise generated 0.7V lower based on the power supply voltage Vcc is introduced.

When the switching device Q1 is turned on, the power supply voltage Vcc is smoothed through the switching device to the capacitor C8 to turn on the switching device Q2.

When the switching element Q2 is turned on, a negative negative frequency into which the noise from the resistor R3 and the condenser C3 flows flows to the ground through the emitter of the switching element Q2 to detect a pilot signal. Negative intermediate frequency is not applied to the unit 103.

As a result, the pilot signal discriminating unit 104A determines that the received broadcast is mono, and applies the corresponding signal to the voice matrix unit 104B to process the received voice signal as mono.

In addition, when the stereo or dual multi-negative intermediate frequency is normal without noise, the 117.5 Hz or 274.1 Hz pilot signal in the 54.68 KHz carrier component of the negative intermediate frequency consists of a capacitor (C7) and a resistor (R5). It is blocked by the high pass filter.

Accordingly, the power supply voltage Vcc is applied to the base of the switching element Q1 through the resistor R5 in a high state, and the switching element Q1 is turned off.

As the switching element Q1 is turned off, the base applied voltage of the switching element Q2 also becomes low and the switching element Q2 is also turned off.

Therefore, when the negative intermediate frequency through the resistor R3 and the condenser C3 is input to the pilot signal detector 103 and the pilot signal is detected, the subsequent operation is the same as the normal operation described above.

As described in detail above, the present invention can remove noise introduced into the sub-negative intermediate frequency during nicamono broadcasting or pure mono broadcasting. As a result, the pilot signal detector can perform normal operation. There is an effect that can prevent.

Claims (2)

A voice intermediate frequency detecting means for detecting a main voice and a sub voice intermediate frequency from the received broadcast signal, and a noise removing means for removing noise at the sub voice intermediate frequency output from the intermediate frequency detecting means. A pilot signal checking means for detecting a pilot signal at a negative negative intermediate frequency output from the intermediate frequency detecting means according to the operation of the noise removing means, and obtained by the voice intermediate frequency detecting means according to a pilot signal obtained from the pilot signal detecting means. A stereo malfunction preventing circuit during mono broadcasting reception, characterized in that it comprises voice processing means for processing main and sub audio. 2. The noise canceling means according to claim 1, wherein the noise removing means includes a capacitor C7 and a resistor R5 for high-pass filtering the negative negative intermediate frequency output from the intermediate detection means, and a frequency filtered by the capacitor C7 and a resistor R5. A first switching element switched by the first switching element, a resistor R6 (R7) for dividing the voltage obtained by the first switching element, and a smoothing capacitor C8 for smoothing the voltage divided by the resistors R6 and R7. And a second switching element which switches according to the voltage obtained by the smoothing capacitor C8 and removes the noise of the negative negative frequency applied to the pilot signal detecting means. .