JPH11234068A - Digital sound broadcasting receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital sound broadcasting receiver capable of reproducing sound which is adapted to actual reception environment and which is easy to listen to, through the use of dynamic range control data transmitted as additional data of digital sound broadcasting. SOLUTION: A dynamic range control(DRC) data extraction means 11, a DRC operation means 16, a coefficient generation means 15 for generating a coefficient in accordance with the output of the DRC operation means 16, a multiplication means 14 for multiplying the output of the DRC data extraction means 11 by the coefficient and a sound amplifier 8 for adjusting sound volume setting based on the multiplied result are provided. The strength of DRC can be increased/decreased so that the sound is adapted to the actual reception environment through the operation of a listener.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention mainly relates to ITU-R
Recommendation BS. No. 774, which relates to a receiver compatible with digital audio broadcasting, in particular, the level of a reproduced audio signal is dynamically controlled by additional information transmitted from a broadcasting station, so that it is easy to hear even in an environment where ambient noise is relatively large. The present invention relates to a dynamic range control function capable of reproducing sound.

[0002]

2. Description of the Related Art Digital audio broadcasting has a transmission method of OF.
Adopts DM (Orthogonal Frequency Division Multiplex) and adds a powerful error correction function to enable high-speed digital data transmission to mobiles with large radio wave propagation problems such as multipath and fading. It is possible. In addition, the adoption of the MPEG audio compression method enables simultaneous transmission of a plurality of high-quality audios equivalent to a CD. However, when a high-quality sound with a wide dynamic range is reproduced in a noisy environment such as an automobile, there is a problem that a weak sound portion is masked by ambient noise and becomes difficult to hear. For this reason,
In the ETS300401 DAB standard, sound volume adjustment data is added to each transmission frame (24 ms unit) of audio data and transmitted.
By adjusting the volume according to this data at the receiver and raising the volume of the low-pitched sound part, a rule for solving the above problem is provided. Since the operation based on this rule controls the dynamic range of the audio signal, the DRC
(Dynamic Range Control). In the following description, this function is described as DRC.

FIG. 5 shows a configuration of a conventional digital audio broadcasting receiver. In the figure, 1 is an antenna, 2 is an RF amplifier, 3 is an A / D converter, 4 is a data demodulator, 5 is an error correction code decoder, 6 is an MPEG audio decoder, 7 is D / A
Converter, 8 is an audio amplifier, 9 is a speaker, 10 is a control device, 11 is DRC data extraction means, 12 is a gate circuit,
Reference numeral 13 denotes a DRC on / off switch.

[0004] In the receiver configured as described above,
The broadcast wave received by the antenna 1 is amplified by the RF amplifier 2, unnecessary components such as adjacent channel waves are removed, and converted into a baseband signal by quadrature demodulation.
It is provided to the D converter 3. The signal sampled by the A / D converter 3 is demodulated by the data demodulator 4. The demodulated data is sequentially output to the error correction code decoder 5 according to the carrier order rule when performing modulation on the transmission side.

[0005] The error correction code decoder 5 cancels time interleaving over a plurality of transmission symbols performed on the transmission side and decodes convolutionally coded and transmitted data. At this time, error correction of data generated in the transmission path is performed. Of the decoded data from the error correction code decoder 5, the audio data is transmitted to the MPEG audio decoder 6 and the DRC data extraction means 11 by the contents of the transmission data,
The configuration data indicating the configuration is output to the control device 10, respectively.

The MPEG audio decoder 6 uses an ISO / MP
The digital broadcast audio data compressed according to the rules of the EG audio layer 2 is expanded and applied to the D / A converter 7. D
The audio signal analog-converted by the / A converter 7 is reproduced from the speaker 9 through the audio amplifier 8.

[0007] The control device 10 controls the RF according to the operation of the listener.
It controls the amplifier 2 to perform tuning control for receiving the DAB broadcast appropriately, and performs fine tuning frequency control for the RF amplifier 2 based on the synchronization signal given from the data demodulator 4. Further, the data demodulator 4 performs fine data demodulation timing control. The control device 10
Decodes the configuration data from the error correction code decoder 5, determines the service to be actually decoded and reproduced from a plurality of services to be transmitted, displays information such as the service name, and displays error correction information. The code decoder 5 performs settings necessary for decoding this service and outputting it to the MPEG audio decoder 6. Further, the control device 10 sets the volume of the audio amplifier 8 according to the operation of the listener.

The DRC extraction means 11 extracts volume adjustment data to be added and transmitted for each transmission frame (24 ms unit) of MPEG audio data, and outputs the volume control input to the audio amplifier 8 through the gate circuit 12. Given as FIG. 6 shows the DR shown in the ETS300401 DAB standard.
It shows the correspondence between the additional data for C control and the volume adjustment data to be controlled. As described above, since there is a one-to-one relationship between the added data for DRC control and the volume adjustment amount, the audio amplifier 8 is provided with a volume adjustment control input of 0.25 dB unit by a binary number to extract the DRC data. DRC control can be performed by giving the DRC control data extracted by the means 11 to this.

Here, the gate circuit 12 supplies the DRC control data from the DRC data extraction means 11 to the audio amplifier 8 as it is in accordance with the state of the DRC on / off switch 13 when the DRC on is instructed, thereby enabling the DRC operation. When DRC off is instructed, fixed control data corresponding to normal volume adjustment of 0 dB is supplied to the audio amplifier 8 to stop the DRC operation.

[0010]

As described above, a conventional digital audio broadcasting receiver performs DRC based on data transmitted from a broadcasting station. However,
The DRC data transmitted from the broadcast station assumes a certain ambient noise, and does not correspond to an actual listening environment. For this reason, when the ambient noise level in the actual reception environment is higher than this assumption, a problem arises in that the weak sound portion of the audio signal becomes difficult to hear. Also, since the DRC data transmitted from the broadcasting station assumes a certain constant average playback volume, if the actual average playback volume is lower than this assumption, the ambient noise level is almost as expected. However, there still arises a problem that the weak sound portion of the audio signal becomes difficult to hear.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a digital audio broadcast receiver capable of reproducing an easily audible sound adapted to actual listening environment conditions and a listener's feeling. Aim.

[0012]

A digital audio broadcasting receiver according to the present invention comprises: a DRC data extracting unit;
DRC operating means for adjusting the strength of the
Coefficient generating means for generating a coefficient according to the output of the operating means, multiplying means for multiplying the output of the DRC data extracting means by the coefficient, and an audio amplifier configured to adjust the volume setting based on the result of the multiplication. It is provided.

[0013] The apparatus further comprises DRC data extraction means, coefficient generation means for generating a coefficient in accordance with a volume set value to the audio amplifier, and multiplication means for multiplying the output of the DRC data extraction means by the coefficient. .

The DRC data extracting means, the ambient noise level detecting means for detecting the ambient noise level, the coefficient generating means for generating a coefficient according to the output of the ambient noise level detecting means, and the output of the DRC data extracting means. A multiplying means for multiplying the coefficient; and an audio amplifier configured to adjust a volume setting based on a result of the multiplication.

When the DRC data is not added to the audio data and transmitted, the DRC data extracting means may be provided with a predetermined fixed D
It is configured to output RC data.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In a digital audio broadcasting receiver according to an embodiment of the present invention, when the noise level in an actual reception environment is different from the assumption in a broadcasting station, the operation of a listener or volume setting information, Alternatively, by changing the DRC data at an appropriate ratio based on the detected ambient noise level, sound reproduction suitable for the reception environment at that time, which is easy for the listener to hear, is performed.

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. FIG. 1 shows a block diagram of a digital audio broadcast receiver according to Embodiment 1 of the present invention. In the figure, 1 is an antenna, 2 is an RF amplifier, 3 is an A / D converter, 4 is a data demodulator, 5 is an error correction code decoder, 6 is an MPEG audio decoder, 7 is a D / A converter, and 8 is An audio amplifier, 9 a speaker, 10 a control device, 11 a DRC data extraction unit, 14 a multiplication unit, 15 a coefficient generation unit,
Reference numeral 16 denotes a DRC operation unit.

Next, the operation will be described. The broadcast wave received by the antenna 1 is amplified by an RF amplifier 2, an unnecessary component such as an adjacent channel wave is removed, and converted into a baseband signal by quadrature demodulation, and supplied to an A / D converter 3. The signal sampled by the A / D converter 3 is demodulated by the data demodulator 4. The demodulated data is
The signals are sequentially output to the error correction code decoder 5 according to the carrier order rule when performing modulation on the transmission side.

The error correction code decoder 5 performs time de-interleaving over a plurality of transmission symbols performed on the transmission side, and decodes convolutionally encoded and transmitted data. At this time, error correction of data generated in the transmission path is performed. Of the decoded data from the error correction code decoder 5, the audio data is output to the MPEG audio decoder 6 and the DRC data extraction means 11, and the configuration data indicating the content and configuration of the transmission data is output to the control device 10.

The MPEG audio decoder 6 uses an ISO / MP
The digital broadcast audio data compressed according to the rules of the EG audio layer 2 is expanded and applied to the D / A converter 7. D
The audio signal analog-converted by the / A converter 7 is reproduced from the speaker 9 through the audio amplifier 8.

The control device 10 controls R according to the operation of the listener.
The F amplifier 2 is controlled to perform tuning control for receiving a DAB broadcast appropriately, and based on a synchronization signal given from the data demodulator 4, fine tuning frequency control is performed for the RF amplifier 2. Further, the data demodulator 4 performs fine data demodulation timing control. Control device 1
“0” decodes the constituent data from the error correction code decoder 5, determines the service to be actually decoded and reproduced from a plurality of services to be transmitted, displays information such as the service name, and displays error information. The correction code decoder 5 performs settings necessary for decoding this service and outputting it to the MPEG audio decoder 6. Further, the control device 10 sets the volume of the audio amplifier 8 according to the operation of the listener.

The DRC extraction means 11 extracts the volume adjustment data to be added and transmitted for each transmission frame (24 ms unit) of the MPEG audio data, and outputs the data to the multiplication means 14.
The multiplication means 14 multiplies the output of the DRC data extraction means 11 and the output of the coefficient generation means 15 and performs rounding so that one step corresponds to a volume adjustment of 0.25 dB as in the conventional example. Give to control input. The coefficient generating means 15 generates coefficient data to be given to the multiplying means 14 according to the state of the DRC operating means 16. Also D
The RC operation means 16 includes (1) DRC off, (2) DRC
ON +/- 0, (3) DRC ON +, (4) DRC ON-, four states are provided.

The coefficient generating means 15 calculates the numerical value "0" when (1) DRC is off, (2) numerical value "1" when DRC on +/- 0, and (3) numerical value "1.
5 ", (4) When the DRC is ON, an output corresponding to the numerical value" 0.5 "is given to the multiplying means 14. Thus, when the coefficient value “0” is given (1) In the DRC off state, the output of the multiplication means 14 becomes 0 irrespective of the data given from the DRC data extraction means 11, and the DRC operation is stopped. Also, a coefficient value “1” is given (2) DR
In the state of C on +/- 0, the output of the multiplication means 14 is DR
Since the data itself is provided from the C data extracting means 11, the same DRC operation as in the related art is performed.

Further, when the coefficient value “1.5” is given (3) When the DRC is ON +, the output of the multiplication means 14 is at the above ratio (1.5) with respect to the data given from the DRC data extraction means 11. Since it is always large, the DRC operation is performed stronger than before. Further, when the coefficient value “0.5” is given (4) When the DRC is ON, the output of the multiplying means 14 is
Is always smaller at the above ratio (0.5) with respect to the data given from, the DRC operation is performed weaker than in the prior art.

FIG. 2 shows this state as the input / output characteristics of the audio amplifier 8. In FIG. 2, reference numeral 100 denotes a characteristic when DRC is not performed, and the relationship between the input level and the output level is a straight line having a slope of 1. This figure 2
In the figure, the fixed gain in the audio amplifier 8 is not shown, but the relationship is the same when there is a fixed gain. Next, reference numeral 101 denotes a DR based on transmission data from a broadcast station.
It shows static input / output characteristics when the C operation is performed. Here, the difference between the characteristic 101 and the characteristic 100 indicated by an arrow 104 in the figure becomes the DRC data transmitted from the broadcasting station. As shown in the figure, the characteristics of the normal DRC are such that the larger the input signal level, the smaller the volume adjustment amount, and the smaller the input signal level, the larger the volume adjustment amount. Therefore, the smaller the slope of the average input / output characteristic is, the stronger the DRC is applied.

The effect of the DRC is that the more it is applied, the more the masking of the weak sound portion of the audio signal is less likely to occur even when the ambient noise level is higher, and it is possible to reproduce a sound that is easy to hear. , Narrowing the range of artistic expression. For this reason, it is desirable that the DRC be reduced to the minimum necessary according to the ambient noise level of the reproduction environment.

A characteristic 102 indicates the input / output characteristic in the state of (3) DRC ON +, and a characteristic 103 indicates the input / output characteristic in the state of (4) DRC ON-.
Thus, in each case, the DRC is (2) DRC ON +
It can be seen that the characteristic is moderately strong and moderately weak compared to the characteristic 101 in the case of / -0. Because of this, the listener
By operating the operation means 16, it is possible to appropriately select the strength of the DRC according to the surrounding noise situation at each time.

Embodiment 2 FIG. 3 shows a block diagram of a digital audio broadcast receiver according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, respectively, and the difference from the first embodiment is that the coefficient generation means 15 outputs the status signal from the DRC operation means 16 and the control device 10 The point is that the volume setting given to the audio amplifier 8 is given and the generated coefficient is controlled. Hereinafter, an operation of a portion different from the first embodiment will be described.

First, when the DRC operation is instructed by the DRC operating means 16, the coefficient generating means 15 outputs a numerical value 0 to the multiplying means 14. As a result, the output of the multiplication means 14 becomes "0" regardless of the data supplied from the DRC data extraction means 11, and the DRC operation is stopped.

Next, when the DRC operation is instructed by the DRC operating means 16, the coefficient generating means 15 becomes "1" for the volume setting which is considered to be the most common, and when the volume setting is larger than this, it becomes "1". If the volume setting is smaller than “1” and the volume setting is smaller than this, a coefficient value larger than “1” is generated. The coefficient value is converted into a numerical value of a number of steps having an appropriate step and provided to the multiplying means 14. The multiplication means 14
The coefficient value is multiplied by the DRC data, rounded, and given to the audio amplifier 8.

According to the second embodiment, when the volume setting is low and the reproduction volume is low, the coefficient generating means 1
Since the coefficient generated by 5 becomes large and the DRC operation is performed strongly, it becomes possible to reproduce a sound that is more audible at the time of reproducing a small volume that is easily affected by ambient noise. Further, in a situation where the volume setting is large and the reproduction volume is large, the coefficient generated by the coefficient generating means 15 becomes small,
Since the DRC operation is also performed weakly, unnecessary dynamic range compression is avoided and sound reproduction more faithful to the original sound can be performed.

Embodiment 3 FIG. FIG. 4 shows a block diagram of a digital audio broadcast receiver according to Embodiment 3 of the present invention. In the drawing, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts, respectively, and reference numeral 18 denotes a sensor, and 19 denotes an ambient noise level detector.

Next, an operation different from that of the second embodiment will be described. When DRC off is instructed by the DRC operating means 16, the coefficient generating means 15 outputs a numerical value 0 to the multiplying means 14. As a result, the output of the multiplication means 14 becomes DRC
Since the value becomes 0 irrespective of the data supplied from the data extracting means 11, the DRC operation is stopped.

Next, when the DRC operation is instructed by the DRC operating means 16, the coefficient generating means 15 becomes "1" for the volume setting considered to be the most general, and "1" when the volume setting is more severe. If the volume setting is smaller than this, a volume correction coefficient value larger than "1" is generated. At the same time, the coefficient generating means 15 is "1" for a noise level that is relatively wide and is likely to be used as a broadcast station assumption, and is larger than "1" when the noise level is higher than this. When the noise level is smaller than this, a noise correction coefficient value smaller than “1” is generated. The coefficient generating means 15 multiplies these two coefficient values, that is, the volume correction coefficient value and the noise correction coefficient value, to generate a final coefficient value. The coefficient value is converted into a numerical value of a number of steps having an appropriate step and provided to the multiplying means 14. The multiplication means 14 multiplies the coefficient value by the DRC data, performs rounding, and provides the result to the audio amplifier 8.

In the third embodiment, the coefficient generated by the coefficient generating means 15 increases as the volume setting and the reproduction volume are lower and the ambient noise level is higher, and the DRC operation is performed more strongly. At the time of low-volume reproduction that is easily affected by ambient noise, when the level of ambient noise is higher than an expected level, sound reproduction that is easy to hear can be performed. Also, as the volume setting and the reproduction volume are higher and the level of the ambient noise is lower, the coefficient generated by the coefficient generator 15 becomes smaller, and the DRC operation is also performed weakly, so that unnecessary compression of the dynamic range is avoided. As a result, sound reproduction more faithful to the original sound can be performed.

In the description of the state embodiment, only the case where the DRC data is transmitted from the broadcasting station has been described. However, the content of the broadcast originally has a dynamic range such as an announcement, a popular song, and some popular music. Since there are audio contents that are so narrow that the effect is not so significant even when DRC is performed, the DRC data may not be transmitted for such a program.

However, even in such a situation where the DRC data is not transmitted, when the DRC operation means 16 is operated, the effect on the voice as a response to these operations is obtained similarly to the case where the DRC data is transmitted. Being present is of practical importance in showing the listener that these controls are working properly.

As a method for realizing this, when the DRC data is transmitted from the DRC data extracting means 11 to the above-mentioned average level of the audio content having a relatively narrow dynamic range, the DRC data is transmitted. It is effective to output a value assumed to be fixed in a fixed manner. In this case, the selection of the strength of the DRC in the first embodiment and the effect on the change of the ambient noise level in the third embodiment are effective. Also, the listener can feel the effect as a change in the reproduction volume.

The value output from the DRC data extracting means 11 is such that the average level of the audio contents having a relatively narrow dynamic range is -15 to-
Since it is about 20 dB, it is equivalent to an adjustment gain of about +2 dB when derived with reference to FIG.

In the first embodiment, for convenience of explanation, the state that can be designated by the DRC operating means is 4 (DR
The control stage of C was set to 3).
It is possible to have a wider (or narrower) DRC variation range. Appropriate restrictions can also be added so that the volume increase due to DRC is not excessive.

In the above description, the DRC data extraction means 11, the multiplication means 14, and the coefficient generation means 15 have been independent means. However, when a microcomputer is used for the control device 10, for example, It is also possible to realize by a program processing as a part of the function.

[0042]

Since the present invention is configured as described above, it has the following effects.

While using DRC data assuming a constant playback volume and noise level transmitted from a broadcasting station,
In accordance with the operation of the listener, it becomes possible to perform the DRC operation that matches the actual listening environment conditions and the listener's feeling. In addition, by using the DRC data transmitted from the broadcasting station, an audio signal level detection circuit, which is indispensable when the receiver independently creates the DRC data, becomes unnecessary, so that the receiver can be configured at low cost. . In addition, by processing based on the transmission data from the broadcasting station, DRC
Compared to the case of creating data, more musically appropriate processing can be performed.

Further, while using DRC data that is assumed to have a constant playback volume and noise level transmitted from a broadcasting station, a DRC that automatically responds to a change in the actual playback volume is used.
The operation can be performed.

Further, it is possible to perform a DRC operation automatically corresponding to a change in an actual ambient noise level while using DRC data which is assumed to have a constant reproduction volume and noise level transmitted from a broadcasting station, This makes it possible to maintain a sound quality that is always easy to hear without bothering the listener.

In addition, even when the DRC data is not transmitted from the broadcasting station, the volume is appropriately increased or decreased, so that it is possible to eliminate an uncomfortable operation. Further, since the volume adjustment amount is automatically increased or decreased based on the detection of the ambient noise, it is possible to always maintain a sound volume that is easy to hear without bothering the listener.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital audio broadcast receiver according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment.

FIG. 3 is a block diagram of a digital audio broadcast receiver according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a digital audio broadcast receiver according to a third embodiment of the present invention.

FIG. 5 is a block diagram of a conventional digital audio broadcast receiver.

FIG. 6 is a diagram showing correspondence between DAB standard additional data for DRC control and volume adjustment data to be controlled;

[Explanation of symbols]

1 antenna, 2 RF amplifier, 3 A / D converter, 4
Data demodulator, 5 error correction code decoder, 6 MPEG
Audio decoder, 7 D / A converter, 8 audio amplifier, 9
Speaker, 10 control device, 11 DRC data extraction means, 14 multiplication means, 15 coefficient generation means, 16 DR
C operation means, 18 sensors, 19 ambient noise level detector.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takahiro Namba 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Masakazu Morita 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd.

Claims (4)

[Claims] 1. DRC transmitted in addition to audio data
DRC data extraction means for extracting data, DRC operation means for adjusting the strength of the DRC, coefficient generation means for generating a coefficient in accordance with the output of the DRC operation means, and output of the DRC data extraction means A digital audio broadcast receiver comprising: a multiplication means for multiplying the coefficient; and an audio amplifier configured to adjust a volume setting based on a result of the multiplication. 2. DRC transmitted in addition to audio data
DRC data extraction means for extracting data, an audio amplifier, coefficient generation means for generating a coefficient according to a volume setting value for the audio amplifier, and multiplication means for multiplying the output of the DRC data extraction means by the coefficient. A digital audio broadcast receiver, comprising: a volume setting of the audio amplifier is adjusted based on a result of multiplication by the multiplication means. 3. DRC transmitted in addition to audio data
DRC data extracting means for extracting data, ambient noise level detecting means for detecting an ambient noise level, coefficient generating means for generating a coefficient according to the output of the ambient noise level detecting means, and an output of the DRC data extracting means. A digital audio broadcast receiver comprising: a multiplication means for multiplying the coefficient; and an audio amplifier configured to adjust a volume setting based on a result of the multiplication. 4. When the DRC data is not added and transmitted to the audio data, the DRC data extracting means performs a predetermined fixed DRC
The digital audio broadcast receiver according to claim 1, wherein the digital audio broadcast receiver is configured to output data.