JPH099236A - Audio output circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] The audio of the program to be recorded in the VTR is directly taken out from the audio demodulation unit. [Structure] After the cursor is moved to a corresponding program position and an instruction is given, when an enter key provided on the remote controller 34 is pressed, the internal sound source unit 1 that generates an operation click sound and the sound demodulation unit 4 generate the click sound. A mixing unit 2 for mixing with a sound of a program or the like to be supplied, a channel selecting unit 3 for receiving and decoding a digital signal of the program or the like supplied by a request,
For example, a voice demodulation unit 4 for demodulating an analog stereo voice from a PCM decoded signal or the like of the channel selection unit 3, and the mixing unit 2
Of the sound output from the sound demodulation section 4 and a ground switch 6 for grounding the output of the internal sound source section 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio output circuit of a set top box (tuner) used for receiving an interactive service in a CATV system or the like.

[0002]

[Prior Art] CATV (Community Antenna Televisi)
on) is a cable television that distributes video programs, video / audio services, etc. to each home by wire. Recently, with the spread of CATV system, which is a more advanced type and provides interactive services, has spread. It's starting. FIG. 3 shows an example of a CATV system that provides interactive services. Reference numeral 30 is a CA that delivers video programs and services composed of images and sounds such as moving images in response to requests from homes.
It is a TV center. 31 is installed in each household, and C
A set top box (STB: tuner) that is connected to the ATV center 30 by wire, requests video programs and services, and receives, decodes, and demodulates images and sounds delivered as a result. Reference numeral 32 is a television that displays video and audio. Reference numeral 33 is a VTR for recording the delivered image / audio. 34 inputs a request,
For example, it is a remote controller or a mouse for operating the STB 31 itself.

In the CATV system, when the STB 31 is activated and a service is selected, for example, a VOD (Video On Demand) service menu screen as shown in FIG. 4 can be displayed on the television 32. Further, when the program is selected by pointing the cursor from the remote controller 34 (in the example of FIG. 4, the title B is designated), as shown in FIG.
For example, by making a request from the BTV 31 to the CATV center 30 for a program selected on the "uplink" configured by a telephone line or the like, the "downlink" from the CATV center 30 side to the STB 31 side, for example, QAM
Supplies video and audio that has been signal-compressed by (Quadrature Amplitude Modulation).

By the way, the received and demodulated video and audio are
Not only is it viewed on the television 32, but it is often recorded on the VTR 33. FIG. 5 is a block diagram of a conventional STB audio output circuit. Reference numeral 1 denotes an internal sound source section that generates an operation click sound when a video program or the like is selected on the menu screen, after moving the cursor to the corresponding program position and instructing, for example, when the Enter key of the remote controller 34 is pressed. is there. Two
Is a mixing unit for mixing the click sound with the sound of a program or the like supplied by the sound demodulation unit 4. Reference numeral 3 denotes a channel selection unit for receiving and decoding a digital signal such as a program supplied by a request. Reference numeral 4 is a voice demodulation unit of the channel selection unit 3 that demodulates an analog stereo voice from a PCM decoded signal or the like.

However, when a video program or the like is recorded in the VTR 33, the conventional audio output circuit shown in the block diagram of FIG. 5 is in a state in which noise from the internal sound source unit 1 is added to PCM decoded audio with high sound quality. Since this is a circuit for recording voice, the S / N of recorded voice is deteriorated.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an audio output circuit capable of recording the S / N of transmitted and demodulated sound without degrading it.

[0007]

In order to achieve the above object, an internal sound source section for generating an operation click sound and the like, a channel selection section for receiving and decoding a supplied signal, and a channel selection section supplied by the channel selection section. In a voice output circuit including a voice demodulation unit that demodulates voice from a decoded signal and the like, and a mixing unit that mixes the click sound and the demodulated voice, the sound output by the mixing unit and the voice demodulation unit And a switch for selecting the sound from.

[0008]

With the above construction, referring to FIG. 1, for example, when selecting a program, the sound output from the mixing section 2, that is, the demodulated sound and the click sound can be heard simultaneously through a speaker such as a television. it can. Further, in the case of voice recording with a good S / N, by selecting the sound from the voice demodulation unit 4 with the switch 5, it is possible to record only the sound of the program or the like independently demodulated in the VTR.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The audio output circuit according to the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 is a block diagram of a first embodiment of an audio output circuit according to the present invention. 1 is an operation click when the enter key provided on the remote controller 34 is pressed after moving the cursor to the corresponding program position and instructing, for example, when activating the STB and selecting a video program etc. on the menu screen. It is an internal sound source that generates sound. Reference numeral 2 is a mixing unit for mixing the click sound with the sound of a program or the like supplied by the sound demodulation unit 4. Reference numeral 3 denotes a channel selection unit for receiving and decoding a digital signal such as a program supplied by a request. 4 is, for example, P of the tuning unit 3.
A voice demodulation unit that demodulates analog stereo voice from a CM decoded signal or the like. 5 is a sound output from the mixing unit 2,
A switch for selecting the sound from the voice demodulation unit 4. Reference numeral 6 is a ground switch for grounding the output of the internal sound source section 1.

The operation of the present invention is shown in FIGS. 1, 3 and 4.
Follow the explanation below. When the STB 31 is activated, a menu screen as shown in FIG. 4 is first displayed on the television 32, and the remote control 34 is used to instruct the cursor to select the corresponding program. As shown in FIG. 3, STB31 to CAT
For example, by making a request to the V center 30 for a selected program via an “uplink” configured by a telephone line or the like, the “downlink” from the CATV center 30 side to the STB 31 side, for example, , QAM (Quadra
ture Amplitude Modulation) is used to supply video and audio signals that have been signal compressed. At this time, the internal sound source unit 1
Generates an operation click sound for each input operation from the remote controller 34 and outputs the operation click sound to the mixing unit 2. Also, the tuning section 3
Receives and decodes the digital modulation signal transmitted from the CATV center 30 side, and the voice demodulation unit 4 operates the channel selection unit 3
The analog stereo sound is demodulated from the decoded signal supplied by and is output to the terminal B and the mixing unit 2. The mixing section 2 mixes the operation click sound supplied by the internal sound source section 1 and the analog stereo sound supplied by the sound demodulation section 4, and outputs the mixed sound to the terminal A. The switch 5 has the terminal A
Alternatively, any one of the terminals B is selected.

A more specific operation of the audio output circuit according to the present invention will be described. For example, when a program is selected, the sound output by the mixing unit 2 to the A terminal, that is, the demodulated sound and the click sound can be simultaneously heard through a speaker such as a television after performing necessary amplification. If you want to record the sound of your favorite program with good S / N, switch 5
By selecting the sound from the audio demodulation section 4, only the sound of the independently demodulated program or the like can be recorded in the VTR. Also,
In FIG. 1, the switch 5 is not provided (the circuit in which the ground switch 6 is provided in FIG. 5), and when the program is selected, the ground switch 6 is opened, and when recording, the ground switch 6 is used.
A similar operation is obtained by closing the.

FIG. 2 is a block diagram of a second embodiment of the audio output circuit according to the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the present invention, the first output system of the mixing section 2 and the second output system of the audio demodulation section 4 are provided independently. Therefore, if the sound of the first output system is used, the demodulated sound and the click sound can be heard at the same time by a speaker such as a TV after performing necessary amplification. Also, by using the sound of the second output system, the sound of a favorite program or the like can be recorded in the VTR with a good S / N.

[0013]

As described above, the present invention provides an audio output circuit capable of recording the S / N of transmitted and demodulated sound without degrading it. Therefore, for example, there is an advantage that high quality PCM decoded voice can be recorded with good S / N.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of an audio output circuit according to the present invention.

FIG. 2 is a block diagram of a second embodiment of an audio output circuit according to the present invention.

FIG. 3 is an example of a CATV system that provides interactive services.

FIG. 4 is a diagram showing a VOD service menu screen.

FIG. 5 is a block diagram of a conventional STB audio output circuit.

[Explanation of symbols]

 1 Internal sound source section 2 Mixing section 3 Tuning section 4 Voice demodulation section 5 Switch 30 CATV center 31 Set top box (STB: tuner) 32 Television 33 VTR 34 Remote control or mouse, etc.

Claims (3)

[Claims] 1. An internal sound source section for generating an operation click sound and the like, and a channel selection section for receiving and decoding a supplied signal.
In a voice output circuit including a voice demodulation unit that demodulates voice from a decoded signal or the like supplied by the channel selection unit, and a mixing unit that mixes the click sound and the demodulated voice, the sound output by the mixing unit And an audio output circuit provided with a switch for selecting the sound from the audio demodulation unit. 2. An internal sound source section for generating an operation click sound and the like, and a channel selection section for receiving and decoding a supplied signal,
In a voice output circuit including a voice demodulation unit that demodulates voice from a decoded signal or the like supplied by the channel selection unit, and a mixing unit that mixes the click sound and the demodulated voice, the sound output by the mixing unit An audio output circuit in which a system for outputting the sound and a system for outputting the sound from the sound demodulation unit are independently provided. 3. An internal sound source section for generating an operation click sound and the like, and a channel selection section for receiving and decoding a supplied signal,
In the audio output circuit including an audio demodulation unit that demodulates audio from a decoded signal or the like supplied by the channel selection unit, and a mixing unit that mixes the click sound and the demodulated audio, the internal sound source unit outputs A voice output circuit with a switch for grounding sound.