JPH02299399A - High vision voice receiver - Google Patents

Abstract

PURPOSE:To make the size of a device small, to improve reliability and to reduce cost by providing a channel mix section comprising a digital multiplier and a digital adder or the like so as to synthesize a 3-1 system four-channel program into a two-channel program. CONSTITUTION:A four-channel digital audio signal inputted to a channel mix section 59 via a parabolic antenna 50, a MUSE tuner 51, an LPF 52, an A/D converter 53, a MUSE audio digital signal processing section 54 is applied prescribed equation arithmetic at a channel mix section 59. That is, a C channel signal and an S channel signal are subject to multiplication of a multiple of 0.7 at digital multipliers 55, 56, and the resulting signal is added to each of LF and RF channel signals at digital adders 57, 58. The synthesized 2-channel digital signals are converted into an analog signal at two D/A converters 60, 61 and LPFs 62, 63 and outputted from audio signal output terminals 64, 65. Thus, the 3-1 system channel program is synthesized into two-channel and reproduced, the small size, low cost and improved performance are attained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a high-definition receiver, and in particular to a channel mix circuit that synthesizes a 3-1 system (3 front channels, 1 rear channel) 4-channel stereo program into 2 channels. It is related to.

(Prior technology) Compared to NTSC televisions, high-definition television receivers have twice the number of scans, a wider screen, and five times the number of pixels, making it possible to achieve high-definition, large-screen displays. You can get a high visual sense of reality. On the other hand, a 3-1 system (3 channels in the front, 1 channel in the rear) and 4 channels of audio is being considered in order to obtain a high sense of realism.

In consideration of the case where multiple people are viewing the video, three channels are provided at the front to ensure good viewing over a wide range with little deviation between the video and audio images, and one independent channel at the rear to enhance the sense of spaciousness.

Let us now consider a method in which a 3-1 system four-channel program is played back by a conventional two-channel audio receiving device. rJAS Conference 88 Proceedings,
According to ``Hi-Vision Viewed from Audio,'' described on pages 220 to 225, the 3-1 method program is expressed as formula (1) L = LF + 0.7C + 0,7S... (1)
R=RF+0.7C+0.7S where LF is the front left channel C is the front center channel RF is the front right channel S is the rear channel.

According to the document, it is noted that if the signals are combined into two channels, there is no significant deterioration in sound quality and it is acceptable.

FIG. 3 is a block diagram showing the configuration of a two-channel audio reproduction dedicated vision system when formula (1) is realized in a simple manner. In the figure, 50 is a radio wave sent from a satellite ( 12GH2) and converts it into an IGHz signal, 51 is a parabolic antenna 50
Select the required channel from the signals sent from M
This is a MUSE tuner that outputs a USE baseband signal. What is MUSE here? (Multiple 5ub
-Nyquist Sampling Encodin
g), which refers to a band compression technology that allows high-definition information, which is five times more than NTSC transmission, to be delayed by one channel of satellite transmission.

The four audio channels are also compressed and time-base multiplexed during the vertical retrace interval of the video signal. 52 is a low-pass filter (hereinafter referred to as LPF) that removes signals outside the band, 53 is an A/D converter, and 54 is a time axis extension, error correction, and dinterleave that separates the audio signal from the video signal and converts it to the audio rate. , a 4-channel digital signal processing unit that performs decoding of the companding differential PCM during condensation, etc., 71 to 74 are D/A converters that convert audio digital signals to analog signals, 75 to 78 are LPFs,
79.80 is an attenuator that multiplies the C channel and R channel audio signals by 0.7, 81.82 is an analog adder, 83 is an L channel audio output terminal, and 84 is an R channel audio output terminal. Attenuators 79 and 80 and analog adders 81 and 82 constitute a circuit 85 that realizes the above equation (1).

Next, the operation will be explained. The radio waves from the satellite received by the parabolic antenna 50 are sent to MUSE tuner 51.
Converted to USE baseband signal, LPF52, A/
The D converter 53 converts it into a digital signal. The audio signal time-axis multiplexed in the retrace interval of the video signal is selected, and the MUSE audio digital signal processing unit 54 decodes the error correction, companding difference PCM during condensation, etc. /A converters 75 to 74 and LPFTs 5 to 78 convert to analog audio signals, and 0.7 times attenuators 79 and 80
, adders 81 and 82 realize equation (1), and two-channel audio outputs are obtained from audio output terminals 83 and 84.

In the conventional device shown in FIG. 4, when a 3-1 system 4-channel program is broadcast as described above, it is possible to combine and reproduce the 2-channel program according to equation (1).

[Problem to be solved by the invention]

The conventional high-television receiving device is configured as described above, and can combine and reproduce signals broadcasted in 3-1 format 4-channel programs into 2 channels according to equation (1), but this is difficult from a cost perspective. When considering the above, there are the following problems.

Although the method shown in Fig. 4 creates a two-channel audio receiving device, it requires four each of D/A converters 71 to 74 and LPFs 75 to 78, which are key parts of digital audio. In order to realize equation (1), a large number of analog components are required, which increases the cost of the audio output section and makes it difficult to downsize.

This invention was made in order to solve the above-mentioned problems, and it is an object to obtain at a low cost a compact, high-performance high-definition audio receiving device that can synthesize and reproduce a 3-1 channel program into 2 channels. With the goal.

[Means to solve the problem]

The high-definition receiving device according to the present invention includes: (1) a digital multiplier and a digital adder with a coefficient of 0°7 that perform the second calculation using digital signals as they are; and a bit shifter that level-shifts the bit length increased by the calculation; a D/A converter that D/A converts the shifted signal;
It is equipped with a level adjuster that adjusts the level of the /A converted signal.

[Effect]

In this invention, a digital multiplier and a digital adder are used to perform the calculation of equation (1) on the digital signal as it is, and the bit length increased by digital multiplication and addition with a coefficient of 0°7. Since the level of is shifted by a bit shifter and the level is increased by an analog signal level adjuster after D/A conversion, the bit length that occurs when formula (1) is simply calculated using the digital signal is An overflow does not occur due to an increase in the number of signals, and a high-definition receiving apparatus capable of reproduction without level fluctuation as a whole can be realized with an extremely simple configuration.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a basic configuration diagram of a high-definition receiver according to an embodiment of the present invention that performs the calculation of equation (1) using digital signals as they are, and corresponds to the conventional example shown in FIG. 3. Second
In the figure, 55.56 is a digital multiplier with a coefficient of 0.7, 57.58 is a digital adder, 59 is a channel mixer that implements equation (1) as a digital signal, and 60.61 is a D/A converter, 62.63 is LPF,
64 is an L channel audio output terminal, and 65 is an R channel audio output terminal.

Next, the operation will be explained. Parabolic antenna 50, M
USE tuner 51, LPF 52, A/D converter 53,
The 4-channel digital audio signal obtained through the MUSE audio digital signal processing section 54 is input to the channel mix section 51, and the C channel signal and the S channel signal are processed by the digital multiplier 55, which performs the calculation of equation (1).
．． 56 and multiplied by 0.7 and added to each of the LF channel signal and RF channel signal by digital adders 57.58. The 0-combined two-channel digital signal is then sent to two D/A converters 60, 61. The signal is converted into an analog signal by the LPF 62.63 and outputted from the audio signal output terminals 64 and 65.

Next, FIG. 1 shows a detailed diagram of the channel mixer and D/A converter. In FIG. 1, 1 is the Lr channel signal, 2 is the R channel signal, 3 is the C channel signal,
4 is each input terminal of the S channel signal, and each signal word length is 16 bits.

5.6 is a digital multiplier with a multiplication coefficient of 0.7 and an output word length of 16 bits. 7.8 is a 16-bit digital signal three-man digital adder, and in the calculation of equation (1), considering the case where the peak signals of all LF, RF, C, and S signals are output at the same time, 1+0 is calculated. .7+0.7=
2. 4 (times), and the addition output becomes 18 bits, an increase of 2 bits. 9 and 10 are 2-bit shift-down bit shifters, 11.12 are 2-man selectors for 16-bit digital signals controlled by the control signal 23, 17.18 are analog amplifiers with a gain of 4 times, and 19.20 is 11.12. an analog signal selector also controlled by the control signal 23;
23 is a control signal input terminal for switching between channel mixing and non-channel mixing.

Next, the operation will be explained. Since this is a case of channel mixing, a control signal is sent from the control signal input terminal 23, and the selectors 11, 12 and 19.20 are set to A.
Connect to the side. L input to input terminal 1゜2.3.4
Each 16-bit input signal of FIR, C, and S is first multiplied by 0.7 in a digital multiplier 5.6, and is then multiplied by 0.7 in a digital multiplier 5.6.
7. SXO.

7 is obtained, and then the digital adder 7.8 obtains the (1st
) expression is calculated. At this time, as already explained, the word length is increased by 2 bits, resulting in an 18-bit output.

The output signal of the 18-bit adder 7.8 passes through bit shifters 9 and 10 for 2-bit downshifting, becomes 16 bits (level becomes 1/4), and is sent to selectors 11 and 12, D/
It passes through A converters 60 and 61 and is converted into an analog signal.

Here, since the D/A converter has a 16-bit input, 2
If connected without downshifting the bits, an overflow will occur in the case of a high-level input signal such that a signal is generated in the upper two bits, causing distortion or abnormal noise to the auditory sense. D/A converter 60.6
The analog output of 1 passes through LPFs 62 and 63 and then enters analog amplifiers 17 and 18, where the level is multiplied by 4 and compensated for by 2 bits down by level shifters 9 and 10. It passes through the selector 19.20- and is output from the H audio output terminal 64.65.

On the other hand, when the signal at the control signal input terminal 23 is switched and the selectors 11, 12, 19, 20 are connected to the B side, the 16-bit input signals LF 1, Rr 2 pass through the selectors 11, 12 and are directly transferred to the D/A converter 60. ,61,
It becomes an analog signal through the LPFs 62 and 63, passes through the selector 19.20, and is output from the audio output terminal 64.65. In either case, the input signal to the D/A converter 60.61 has a maximum level of 16 bits and does not overflow, and the output signal level of the output terminal 64.65 is as shown in equation (1). Become.

In the above embodiment, the input signal word length is 16 bits, but other bit lengths (L bits; L is an integer) may be used. In order to prevent the signal from overflowing in the D/A converter (input word length is M bits, 2 M is an integer), a bit shift (2 (L*ri - M times)) is performed before D/A conversion. Afterwards, adjust the level using an analog amplifier by the amount of bit shift (2 (L''!
)-4 times) has the same effect as the above embodiment.

The above embodiment is a case where LM=16 (bits).

〔Effect of the invention〕

As described above, according to the present invention, in a two-channel high-definition audio receiver, a 3-1 channel program is synthesized into two channels as digital signals, so that the D/A converter and LPF are Only two channels are required for each, the number of analog components can be reduced, and since the synthesis is performed using a digital circuit, reliability and precision are good, and it is also suitable for LSI integration, resulting in lower total costs. There is.

[Brief explanation of drawings]

FIG. 1 is a detailed diagram of a channel mixer and D/A converter according to an embodiment of the present invention, and FIG. 2 is a configuration of the audio section of a two-channel audio high-visibility television receiver using a digital channel mixer circuit. FIG. 3 is a configuration diagram of an audio diagram of a two-channel audio high-definition television receiver using an analog channel circuit. 5.6 is a digital multiplier with a coefficient of 0.7, and 7°8 is a 3
Manual digital adder, 9. lO is a bit shifter, 6
0.61 is a D/A converter, and 17 and 18 are analog level adjusters. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) 3-1 system (3 front channels, 1 rear channel) 4 channel PCM audio program (quantized word length L
Bit: L is an integer) is expressed as equation (1) L=LF+0.7C+
0.7S R=RF+0.7C+0.7S...(1) LF: Front left channel, RF: Front right channel, C: Center channel, S: Surround channel, synthesizes into a 2-channel audio program and plays 2-channel audio. In a high-definition receiving device that performs Integer) D/A converter and 2^-^(^L^+^2^)^-^M times ({(L+2
)−M}>0) and a bit shifter of 2^(^L^+^2
^)^-^ M times the analog level adjuster, and the digital multiplier and the digital adder
), and then converts the synthesized 2-channel digital signal to D/A.
When converting into an analog signal, the 2^-^(^L^+^2) is input to the input of the D/A converter.
^)^-^M times a bit shifter and said 2^(^L^+^2^)^-^M times analog level adjuster are provided at the output of said D/A converter. High-definition receiver.