JPS5819083A - Television sound receiver - Google Patents

Abstract

PURPOSE:To perform an excellent sound reproduction, by attenuating buzz only at the reception of sound multiplex signals, through the insertion of a filter circit attenuating the buzz component between a sound demodulation circuit and a sound amplifier/output circuit. CONSTITUTION:Filters 14, 16 and a filter switching circuits 15, 17 are provided between a sound demodulation circuit 6 and sound amplifier/output circuits 8 and 9. The characteristic of the filters 14 and 16 is that of steep attenuation near 1/2fh (horizontal synchronizing signal) and the filter switching circuits 15 and 17 pass a demodulation signal through the filters 14 and 16 at sound multiplex reception attenuate the frequency component of 1/2fh and in case of reception of the other broadcast, the signal does not pass through the filters and the circuit 6 and the circuits 8 and 9 are directly coupled. Thus, in the case of the reception other than the sound multiplex signals, an input signal is outputted as it is, and in case of the reception of the sound multiplex signals, the output signal characteristics with attenuated 1/2fh component can be obtained.

Description

[Detailed description of the invention] In addition to the video carrier wave, two
In a television receiver having two audio carrier waves, noise with a frequency component half the frequency of the horizontal synchronization signal appears during demodulation of the audio signal. If this noise component is large, the sound quality will deteriorate. The present invention aims to improve the sound quality of a television audio multiplex receiver by attenuating this noise component using a filter.

The West German TV audio multiplex receiver is constructed as shown in FIG. That is, the radio waves received by the receiving antenna (1) are tuned by the tuner (2), pass through the VIP (3), and are separated into SIF (4) and SIF (B) (5) and detected. The signal enters the audio multiplex demodulation circuit (6) and multiplex discrimination switching circuit (7), is demodulated into an audio signal, and is sent to the R channel (main) audio amplification output circuit (8) and the R channel (main) audio amplification output circuit (8).
Sub) Audio amplification output circuit (supplied to 91, R channel (main) audio output terminal 00 and R channel (sub) audio output terminal (11) K R channel and R channel audio signals are output. α2 is a video signal. In the amplifier circuit, σ3 is a video signal output terminal.

The signal spectrum of television radio waves is shown in Figure 2. In the figure, jp is the video carrier, fs is the first audio carrier, fs2 is the second audio carrier, /s is =
fp is +5.5MHz, and the frequency relationship between fsl and fs2 is fS2=fS engineering+31/2. fh However, fh is the horizontal synchronization signal frequency, 15.625
It is KHz. Therefore, fs2=fp+! 5.71121
It is 11575MHz.

Therefore, in S engineering F (4) and (5), the noise component called buzz (hereinafter referred to as buzz) is
Occurs within the audible frequency band as shown in . Same figure (a)
is the case of 5IF (4), and the buzz frequency is 5.5MH
z 10%fh= 5.711MHz -15X/h (S
I F (buzz component of (5)), the same figure (b) is S I
In the case of F (5), the buzz frequency is
) is the buzz component). Because of this mechanism, the sound quality of the reproduced audio signal deteriorates.

The present invention aims to attenuate this buzz component and realize reproduction of high-quality audio signals.

FIG. 4 shows a circuit configuration of an embodiment of the present invention.

In this figure, parts that are the same as those in FIG. 1 are designated by low symbols. From the antenna (1) to the multiplex selection switching circuit (7) t is the same as that described with reference to FIG. In the present invention, the filter α41. The characteristics of α(Q and filter switching circuit ('5!+Q7+) are added. This filter 04) and αG are % as shown in Figure 5 (C).
The characteristic pr is such that it attenuates steeply near fh,
In addition, the filter switching circuit 071 allows the demodulated signal to pass through the filters α4) and αG during voice multiplex reception:! When receiving other broadcasts by attenuating the 4fh frequency component, the signal is not passed through the filter (3) but instead is passed through the audio multiplexing/demodulation circuit (6) and the audio amplification/output circuit (
8'l, (9) are directly connected. Such a filter Q41. (t■ and filter switching circuit 05)
, α7j, the input signal as shown in FIG. 5(a) is output as is as shown in FIG. 5(b), except when an audio multiplex signal is received. Also, when receiving an audio multiplex signal, the %fh component is attenuated (as shown in the same figure)
The output signal characteristics will be as shown in .

In this way, according to the present invention, the components other than the audio multiplex reception section are completely the same as the conventional ones, and only during audio multiplex reception, the buzz is attenuated and high-quality audio reproduction can be obtained.

[Brief explanation of drawings]

8I! Figure 1 shows the configuration of the great two-carrier audio multiplex receiver circuit, and Figure 2 shows the configuration of the two-carrier audio multiplex receiver circuit.
Figure 3 is the spectrum of the SIF signal, Figure 4 is a diagram showing the circuit configuration of an embodiment of the present invention,
FIG. 5 is a diagram showing the frequency characteristics of each part in FIG. 4. (21-q-knee f, (3)・VIP, (4)
,・5IF(A). (5)...5IF(B), (6)...Audio multiplexing/demodulation circuit, (7)...Multiple (11) type discrimination switching circuit, (8)...L channel (main) amplification/ Output circuit, (91...R channel (sub) amplification Φ output circuit, 00...R channel audio output terminal,
Marshal: R channel audio output terminal, α2: Video amplification circuit, α411 head: Filter, Q, 51
．． α7j...filter switching circuit. Name of agent: Patent attorney Etsuji Yoshizaki Figure 1 Figure 2

Claims (1)

[Claims] In an audio multiplex television receiving device having two audio carrier waves, a first and a second audio carrier wave, in addition to a video carrier wave,
A television audio receiving device characterized in that a filter circuit for attenuating buzz components is inserted between an audio demodulation circuit and an audio amplification/output circuit.