JPH05103399A - Digital audio signal processor - Google Patents

Abstract

PURPOSE:To easily add a function to a digital signal processor. CONSTITUTION:An additional unit 25 can be loaded or unloaded on or from a digital signal processor 21. DSP circuits 30, 35 give acoustic effects, such as control of sound fields, variation of frequency characteristics, etc., by performing arithmetic processing on acoustic signals converted into digital signals. When the additional unit 25 is added to the processor 21, the DSP circuit 35 is also added and the number of functions which can be realized by digital signal processing is increased. The circuit 35 does not require any conversion circuit for converting the digital signals into analog signals, because the other DSP circuit 30 inputs and outputs the digital signals in the processor 21. A microcomputer 33 detects the presence/absence of the unit 25 and switches a change-over switch 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio digital signal processing apparatus for applying an acoustic effect by performing a digital operation on an audio reproduction signal in an audio apparatus or the like.

[0002]

2. Description of the Related Art FIG. 5 shows the configuration of a conventional audio digital signal processing apparatus. The analog signal for sound reproduction from the analog reproduction device 2 such as a tape recorder is given to the digital signal processing device 1. The output from the digital signal processing device 1 drives the speaker 4 via the output amplifier 3. An additional unit 5 can be connected between the digital signal processing device 1 and the output amplifier 3.

In the digital signal processing apparatus 1, a digital signal processing (hereinafter abbreviated as "DSP") circuit 10, an analog / digital conversion (hereinafter abbreviated as "A / D") circuit 11, a digital / analog conversion ( A circuit 12, a microcomputer 13, an operation input circuit 14, and the like are included. The DSP circuit 10 is A /
The digital signal from the D circuit 11 is arithmetically processed, and the arithmetic result is given to the D / A circuit 12. The A / D circuit 11 converts the sound reproduction analog signal from the analog reproduction device 2 into a digital signal. The microcomputer 13 follows the instruction given to the operation input circuit 14, and the DSP circuit 1
Control 0.

The additional unit 5 includes a DSP circuit 15, A
A / D circuit 16 and a D / A circuit 17 are included. DSP
15 is controlled by the microcomputer 13 in the digital signal processing apparatus 1, and D in the digital signal processing apparatus 1 is controlled.
Digital signal processing is further performed on the acoustic signal processed by the SP circuit 10.

The DSP circuits 10 and 15 realize functions such as a digital filter by software including high-speed arithmetic processing and perform various kinds of processing on reproduced signals. The processing includes sound field control and frequency characteristic change. Since the DSP circuits 10 and 15 realize various functions by high-speed software processing, the number of functions that can be realized is limited. Therefore, when a lot of processing is required, the DSP unit 10,
It is necessary to add 15.

[0006]

In the conventional audio digital signal processing apparatus, when it is desired to increase the function of digital signal processing, it is necessary to add an additional unit 5 as shown in FIG. However, in the configuration in which such an additional unit 5 is added, the analog output from the D / A circuit 12 in the digital signal processing device 1 is
The A / D circuit 16 in the additional unit 5 needs to be converted into a digital signal. The state of the analog signal between the D / A circuit 12 and the A / D circuit 16 is easily affected by noise or the like. At the time of digital conversion by the A / D circuit 16,
Quantization noise may occur.

As described above, in the conventional audio digital signal processing device, if an additional unit or the like is used to increase the function, the quality of the audio reproduction signal may deteriorate. Further, the digital signal processing requires the unnecessary D / A circuit 12 and A / D circuit 16, which increases the cost of the audio digital signal processing device.

An object of the present invention is to provide an audio digital signal processing device to which a digital signal processing function can be easily added.

[0009]

SUMMARY OF THE INVENTION According to the present invention, in a digital audio signal processing apparatus for performing digital arithmetic processing on a signal to be reproduced acoustically to add a desired acoustic effect, a digital signal for arithmetic processing is directly input. A processing device body that can output and that can be attached to and detached from the processing device body. When attached to the processing device body, the processing device digital signal from the processing device body is subjected to arithmetic processing, and a digital signal representing the calculation result is output to the processing device body. It is detected whether the additional processing device to be attached to the processing device and whether the additional processing device is installed in the processing device main body.When the additional processing device is not installed, digital processing is performed only by the processing device main body, and the additional processing device is installed. And a control means for controlling the main body of the processing device and the additional processing device so as to perform the digital arithmetic processing. A.

[0010]

According to the present invention, the audio digital signal processing device includes the processing device main body, the additional processing device, and the control means, and the signal for reproducing the sound is subjected to digital arithmetic processing to add the sound effect. To do. Digital signals for arithmetic processing can be directly input / output to / from the processing apparatus main body. The additional processing device can directly input / output digital signals to / from the processing device main body. The control means detects that the additional processing device is attached to the processing device main body, and controls the processing device main body and the additional processing device to perform digital arithmetic processing. When the additional processing device is not attached, the control means controls the processing device main body to perform digital arithmetic processing.
As a result, it is possible to easily add the function of the digital arithmetic processing only by mounting the additional processing device on the processing device main body.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an audio digital signal processing apparatus according to an embodiment of the present invention. A reproduction acoustic signal from the analog reproduction device 22 is given to the digital signal processing device 21, which is the main body of the processing device. Examples of the analog reproducing device include a magnetic tape recorder and an FM broadcast receiving tuner. The output from the digital signal processing device 21 is power-amplified by the output amplifier 23, and the speaker 2
4 is driven to make it sound. The function of the digital signal processing device 21 can be increased by mounting an additional unit 25 which is an additional processing device. The digital signal processing device 21 is provided with an analog input terminal 26, and a signal for sound reproduction is given from the analog reproduction device 22 through a signal line 27. The digital signal processing device 21 is also provided with a digital input terminal 28, and can input digital signals from, for example, a compact disc (abbreviation “CD”) or a digital audio tape (abbreviation “DAT”). From the output terminal 29 of the digital signal processing device 21, the acoustic signal subjected to the digital arithmetic processing is output as an analog signal.

In the digital signal processor 21, a DSP is provided.
A circuit 31, an A / D circuit 31, a D / A circuit 32, a microcomputer 33 and an operation input circuit 34 are included.
The DSP circuit 30 is provided with input terminals 30i and 30j, output terminals 30f and 30r, and a control terminal 30c.
An input signal input from the analog input terminal 26 and converted into a digital signal by the A / D circuit 31 is applied to the input terminal 30i. The input signal from the digital input terminal 28 is applied to the input terminal 30j. Signals from the output terminals 30f and 30r of the DSP circuit 30 are applied to the input terminal 35i of the DSP circuit 35 included in the additional unit 25. The output terminal 35o of the DSP circuit 35 is
It is connected to the individual contact 36a of the changeover switch 36. The other individual contact 36b of the changeover switch 36 is connected to the output terminals 30f and 30r of the DSP circuit 30. The common contact 36c of the changeover switch 36 is connected to the input of the D / A circuit 32.

The DSP circuit 30 is controlled by a signal from a microcomputer 33, which is a control means, via a control line 37. The DSP circuit 35 is controlled by a signal from the microcomputer 33 via the control line 38. The changeover switch 36 is changed over by a signal from the microcomputer 33 through the changeover line 39. The microcomputer 33 can detect whether or not the additional unit 25 is attached via the control line 38, and when the additional unit 25 is attached, the common contact 36c of the changeover switch 36 via the changeover line 39. Is switched to be connected to the individual contact 36a side. When the additional unit 25 is not mounted, the common contact 36c of the changeover switch 36 is switched to the individual contact 36b side. The connection between the digital signal processing device 21 and the additional unit 25 is a DS of the digital signal processing device 21.
Between the P output terminal 41 and the DSP input terminal 42 of the additional unit 25, between the DSP output terminal 43 of the additional unit 25 and the D / A input terminal 44 of the digital signal processing device 21, and control of the digital signal processing device 21. Input / output terminal 45
And the control input terminal 46 of the additional unit 25.

FIG. 2 shows the function of the DSP circuit 30 shown in FIG. The DSP circuit 30 has a function as shown in FIG. 2A according to a predetermined program.
The input terminals 30i and 30j have switch circuits 50i and 50j.
j are connected respectively. Switch circuits 50i, 50j
Are commonly connected and given to the early reflection sound generation circuit 51, the reverberation sound generation circuit 52 and the mixing circuit 53. The switch circuits 50i and 50j are switched according to an input signal applied to the digital signal processing device 21. The outputs from the initial reflected sound generation circuit 51 and the reverberation sound generation circuit 52 are given to the mixing circuits 53 and 54. The front side output is derived from the mixing circuit 53 via the output terminal 30f. The rear side output is derived from the mixing circuit 54 via the output terminal 30r. 2 (2) is shown in FIG.
(1) Shows a sound field reproduction function realized by the illustrated configuration. When the original sound is generated at time t0, times t1 and t
The initial reflected sound is generated at 2, t3, and t4, and the reverberant sound is generated from time tm to tn. By setting these output levels and time intervals, it is possible to simulate the sound field of a concert hall or the like, and adjust the atmosphere during music reproduction to increase the sense of presence.

FIG. 3 shows a schematic configuration of the DSP circuit 30,
The function realized by this is shown. 3 (1) shows a schematic configuration, FIG. 3 (2) shows a tone control function, FIG. 3 (3) shows a parametric equalizer function, and FIG. 3 (4) shows a graphic equalizer function. These functions are realized by IIR type and FIR type digital filters.

The DSP circuit 35 shown in FIG. 3A includes an arithmetic circuit 55, a random access memory (hereinafter abbreviated as "RAM") 56, a backup battery 57, and the like. The arithmetic circuit 55 arithmetically processes the signal input from the input terminal 35i according to the parameter set in the RAM 56, and derives the signal from the output terminal 35o. The parameters given via the control terminal 35c are set in the RAM 56. The contents stored in the RAM 56 are held by the backup battery 57.

FIG. 3 (2) shows the tone control function realized by the configuration of FIG. 3 (1). With the tone control function, the gain level Ll is variable at low frequencies below the frequency fl, and at high frequencies above the frequency fh,
The gain level Lh is variable.

FIG. 3C shows the function of the parametric equalizer realized in FIG. 3A. In the parametric equalizer, the center frequency f ₀ is variable like F and the gain is also shown as L. It is variable, and Q representing the shape of the characteristic curve is also variable.

FIG. 3 (4) shows the function of the graphic equalizer realized in FIG. 3 (1). In the graphic equalizer, the frequency and the shape of the characteristic curve are fixed,
The gain can be changed. The graphic equalizer shown in FIG. 3 (4) divides one octave into 1/3 bands,
It is adjustable at each frequency.

FIG. 4 shows the external structure of the embodiment shown in FIG. For example, in an in-car audio device, a digital signal processing device 21 is provided in a trunk room or the like, and a reproduction signal is given via a signal line 27 from an analog reproduction device 22 provided in a dashboard or the like near the driver's seat. .. The additional unit 25 can be inserted by opening the lid of the digital signal processing device 21.

In a car audio system, etc.,
With the configuration shown in FIG. 4, a tuner or the like as the analog reproducing device 22 can be provided with operation input means for controlling the digital signal processing device 21.

A digital signal processing device 2 as shown in FIG.
Various functions can be realized by adding the additional unit 25 to 1. For example, when the digital signal processing device 21 alone realizes only the tone control function, the additional unit 25 can be added to realize the function of the graphic equalizer.
Further, in the digital signal processing device 21 alone, when the front side 3 band and rear side 4 band parametric equalizers are realized, by adding the additional unit 25, the front side and rear side 7 band parametric equalizers are added. Can be realized. According to the present embodiment, it is easy to add a function as needed by the user and not include an unnecessary function.
Multiple functions can be realized in a limited space. Even when the additional unit 25 is added, the function of the additional unit may be switched between active and inactive by a switch.

[0023]

As described above, according to the present invention, it is possible to increase the functions realized by the digital arithmetic processing only by mounting the additional device on the main body of the processing device. An arithmetic processing digital signal can be directly input / output from the processing apparatus main body, and the additional processing apparatus performs arithmetic processing on the arithmetic processing digital signal from the processing apparatus main body and gives a digital signal representing the result to the processing apparatus main body. The control means detects whether or not the additional processing device is mounted, and when the additional processing device is mounted, performs digital signal processing using the processing device main body and the additional processing device. Can be easily increased. Further, the processing apparatus main body can directly input / output the arithmetic processing digital signal, and the additional processing apparatus performs arithmetic processing on the arithmetic processing digital signal from the processing apparatus main body, and gives the processing apparatus main body a digital signal representing the arithmetic result. Therefore, it is not necessary to convert the signal into an analog signal on the way, and the cost and noise can be reduced by simplifying the configuration.

Further, according to the present invention, the digital signal processing can be performed only by the processing apparatus main body, and the function can be increased by adding the additional processing apparatus. By preparing multiple types of additional processing device functions and selecting them as necessary, you can select the combination that realizes many types of functions, including the specifications of the processing device itself, and efficiently select the required functions. Can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic electrical configuration of an embodiment of the present invention.

2 is a diagram showing an equivalent configuration and function of a DSP circuit 30 shown in FIG.

3 is a diagram showing an equivalent configuration and function of a DSP circuit 35 shown in FIG.

4 is a perspective view of the embodiment shown in FIG. 1. FIG.

FIG. 5 is a block diagram showing a schematic configuration of a conventional audio digital signal processing device.

[Explanation of symbols]

 21 Digital Signal Processing Device 22 Analog Reproducing Device 23 Output Amplifier 24 Speaker 25 Addition Unit 30, 35 DSP Circuit 31 A / D Circuit 32 D / A Circuit 33 Microcomputer 34 Operation Input Circuit 51 Initial Reflection Sound Generation Circuit 52 Reverberation Sound Generation Circuit 53, 54 mixed circuit 55 arithmetic circuit 56 RAM

Claims (1)

[Claims] 1. A digital audio signal processing apparatus for performing digital arithmetic processing on a signal to be reproduced acoustically to add a desired acoustic effect, and a processing apparatus body capable of directly inputting and outputting an arithmetic processing digital signal, An additional processing device that is detachable from the processing device main body and, when attached to the processing device main body, performs arithmetic processing on the arithmetic processing digital signal from the processing device main body and gives a digital signal representing the calculation result to the processing device main body; Detects whether or not an additional processing device is installed in the main body of the device. When the additional processing device is not installed, digital arithmetic processing is performed only by the processing device main body. When the additional processing device is installed, the processing device main body and the addition are added. A digital signal processing device for audio, comprising: a control unit that controls the processing device to perform digital arithmetic processing.