JPH03218185A - Receiver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial field of application] Stereo audio for overseas audio multiplex compatible television receivers, etc.
This invention relates to a second audio (SAP) signal processing circuit.

[Prior art]

As shown in FIG. 2, the audio multiplexed composite signal l is separated into a stereo synthesized audio signal A and a secondary audio signal B of the second audio (SAP) by a low-pass filter 2 and a band-pass filter 8, respectively. The synthesized audio signal A is passed through a low-pass filter 3 and connected to one input of a matrix circuit 7 as a sum signal (L+R) of stereo left and right audio, and the stereo synthesized audio signal A is further AM-demodulated by a stereo demodulator 5 to generate a stereo signal. The left and right audio difference signal (L-R) and the sub-audio signal obtained by FM demodulating the SAP sub-audio signal B by the SAP demodulator 9 are connected to the stereo/SAP signal switching circuit 12, and the signal switching circuit 12 output (L -R)/SAP to the other input of the matrix circuit 7; In the case of stereo audio input, the stereo/SAP signal switching circuit 12 is automatically or manually switched to the stereo side, and the stereo left and right audio difference signal (L-R) output from the stereo demodulator 5 and the stereo output from the low-pass filter 3 are output. A sum signal (L+R) of left and right audio is input to a matrix circuit 7, and the matrix circuit 7 outputs stereo left and right audio signals L and R.

In addition, in the case of SAP audio input, the stereo/SAP signal switching circuit 12 is automatically or manually switched to the SAP side, and the S
Input the sub-audio signal output from the AP demodulator 9 and the main channel signal output from the low-pass filter 3 to the matrix circuit 7,
The matrix circuit 7 outputs SAP main and sub audio signals M and S. Therefore, the stereo audio signal and the SAP audio signal cannot be output simultaneously.

[Problem to be solved by the invention]

The present invention has been made in view of the prior art, and provides a circuit for simultaneously outputting stereo audio broadcasts and second audio (SAP) broadcasts when both broadcasts are simultaneously broadcast.

[Means to solve the problem]

The present invention uses a sum (L+R) signal circuit of stereo left and right audio as a common circuit for the main channel of stereo audio broadcasting and second audio (SAP) broadcasting, and makes the difference (L- R) Signal circuit and SAP
The feature is that the auxiliary audio signal circuit for audio signals is separated, and the output matrix circuit is also independent.

[Effect]

In FIG. 1, a voice multiplexed composite signal 1 is passed through a band-pass filter 8 to extract a third voice signal B of a second voice (SAP), and the sub-voice signal B is demodulated by a SAP demodulator 9.

On the other hand, the audio multiplexed composite signal 1 is passed through a low-pass filter 2 to obtain a stereo composite signal A in which the S=AP audio signal is deleted, the main channel signal is passed through a low-pass filter 3, and the sub-channel signal is By the stereo demodulator 5,
Matrix circuit 7 as a sum signal (L + R) of stereo left and right audio and a difference signal (L-R) of stereo left and right audio, respectively.
and outputs stereo left and right audio signals L and R.

Furthermore, the SAP sub-audio signal output from the SAP demodulator 9 and the sum signal (L+R) of the stereo left and right audio are input to the matrix circuit 11, and the SAP main and sub-audio signals M and S are combined with the stereo left and right audio signals L and R. Output simultaneously.

〔Example〕

BACKGROUND ART In the United States, television audio multiplex broadcasting, particularly at CATV stations, etc., is implementing simultaneous broadcasting of stereo audio broadcasting and independent second audio (SAP) broadcasting. As shown in FIG. 1, the audio multiplexed composite signal 1 output from an audio detection circuit (not shown) is passed through low-pass filters 2 and 5 fx with a cutoff frequency of 50 KHz.
(fN horizontal scanning frequency) band-pass filter 8 separates the stereo audio synthesis signal A and the SAP sub-audio signal B. The SAP sub-audio signal B separated by the bandpass filter 8 is FM demodulated by the SAP demodulator 9, and the SAP signal is
Connect to the noise reduction circuit 10 of BX-Tν. Furthermore, the separated stereo audio synthesis signal A is divided by the low-pass filter 2, and one is connected to the de-emphasis circuit 4 through the low-pass filter 3 with a cutoff frequency of 15 KHz as a sum signal (L+R) of the stereo left and right audio of the main channel. death,
The other is AM demodulated by the stereo demodulator 5 and output as a difference signal (L-R) between the stereo left and right audio of the sub-channel to dBx-TV.
is connected to the noise reduction circuit 6. Stereo audio broadcast and S
At the time of simultaneous broadcasting of AP audio broadcast, the stereo audio signal is a sum signal (L+R) of the output of the de-emphasis circuit 4 and a difference signal (L-R) of the output of the noise reduction circuit 6, respectively.
The stereo left and right audio L and R are outputted from the matrix circuit 7. At the same time, the SAP audio signal is inputted to the second matrix circuit 11 by inputting the output signal of the de-emphasis circuit 4 of the main channel and the SAP sub-audio signal of the output of the noise reduction circuit 10, respectively. Output audio signals M and S. By simultaneously outputting the stereo audio signal and the SAP audio signal, it is possible to record the SAP audio while listening to the stereo audio, or conversely, record the stereo audio while listening to the SAP audio.

〔Effect of the invention〕

As described above, the present invention provides the sum of stereo left and right audio (L+R
) The signal circuit is a common circuit for the main channel of the stereo audio broadcast and the second audio (SAP) broadcast, and the stereo audio difference (L-R) signal circuit of the sub channel and the SAP sub audio signal circuit are separated and made independent. By connecting to a matrix circuit, it is possible to simultaneously output stereo audio and SAP audio, and it can also be used to record background audio.

[Brief explanation of drawings]

FIG. 1 shows a stereo sound and a second
Block Diagram of Audio (SAP) Processing Circuit FIG. 2 is a block diagram of a conventional example of the same processing circuit. l is an audio multiplexed composite signal, 2 and 3 are low-pass filters, 4
is a de-emphasis circuit, 5.9 is a demodulator, 610 is a noise reduction circuit, 7 and 11 are matrix circuits, 8 is a band pass filter, 12 is a switch for switching between stereo and second audio, A is a stereo synthesized audio signal, B is a sub-audio signal of the second audio.

Claims (1)

[Claims] In overseas audio multiplex compatible TV receivers, etc., the audio multiplexed composite signal is filtered into a stereo synthesized audio signal and a second audio signal.
The synthesized stereo audio signal is separated and demodulated into a sum signal of the stereo left and right audio of the main channel and a difference signal of the stereo left and right audio of the sub channel, and the same signal is obtained as the sum signal of the stereo left and right audio. A difference signal between the stereo left and right audio is connected to a first matrix circuit, and a sum signal of the same stereo left and right audio and a demodulated sub-audio signal of the sub-audio signal of the second audio output from the filter are connected to a second matrix circuit. 1. A receiver, wherein said receiver is connected to said first matrix circuit and outputs stereo left and right audio signals and a main and sub audio signal of a second audio simultaneously from said first matrix circuit output and said second matrix circuit output, respectively.