JP2001249795A - Voice processing board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a voice processing board capable of outputting an arbitrary tone signal without increasing a circuit scale. SOLUTION: A command CD to designate frequency components and an output level constituting a voice signal AS to be outputted is applied from a PC 10 main body to a voice processing board 20A mounted on an extended slot. An arithmetic processing part 28 of the voice processing board 20A calculates the instantaneous value of the signal waveform of each output frequency component in each timing of a sampling signal SS according to the received command CD, and outputs the total value as sampling data SD. The sampling data SD are applied to a DAC 26, and converted into the analog voice signal AS, and outputted from an output terminal 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio processing board mounted in an expansion slot of a computer such as a personal computer (hereinafter, referred to as "PC").

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing an example of a conventional voice processing board. This voice processing board 20 is a PC1
The audio signal AS such as a tone signal is output according to a command CD provided from the PC 10 and used by being mounted in an expansion slot 0.

[0003] The PC 10 is a central processing unit (hereinafter referred to as "CP").
U ”), ROM (Read Only Memory) or RA
Main memory (MEM) such as M (Random Access Memory)
And an auxiliary storage device such as a hard disk drive (HDD) 13, which are interconnected via a system bus 14. The system bus 14 is further connected to a bus bridge 15 for connecting various processing boards mounted in the expansion slots.

On the other hand, the audio processing board 20 has a bus interface (hereinafter, referred to as "I / F") 21 for connecting to the PC 10 via an expansion slot. The control unit 22 is connected to the I / F 21. The control unit 22 decodes a command CD given from the PC 10 via the I / F 21 and controls the output of the audio signal AS of the designated frequency. The control unit 22 is supplied with a clock signal CK as a reference for a control operation from the timing circuit 23.

The timing circuit 23 further includes an audio signal A
A sampling signal SS serving as an S output timing is generated, and the sampling signal SS is supplied to the counter 24. The output side of the counter 24 is RO
It is connected to the lower address terminal AL of M25. RO
The output side of the control unit 22 is connected to the upper address terminal AH of M25. A data terminal DO on the output side of the ROM 25 is connected to a digital-to-analog converter (hereinafter referred to as “DA
C ”) 26). DAC2
The output side of 6 is connected to an output terminal 27, from which an audio signal AS is output.

The ROM 25 stores sampling data S1 of a tone signal based on a single frequency specified by a command CD given from the PC 10 or a combination of a plurality of frequencies.
D is stored in advance. That is, a signal SL for selecting the type of the tone signal is supplied to the upper address terminal AH of the ROM 25, and a signal CN for sequentially counting up at a constant sampling period is supplied to the lower address terminal AL, so that a desired signal is output from the data terminal DO. Are sequentially output. In such an audio processing board 20, the PC 1
0, when the command CD is given from the main unit, the control unit 22 decodes the command CD, and the type of the corresponding tone signal is set to the upper address terminal AH of the ROM 25 as the signal SL.
Given to.

On the other hand, from the timing circuit 23, for example, 8
The sampling signal SS of kHz is supplied to the counter 24. The counter 24 outputs a count value that counts up by one every 125 μs based on the sampling signal SS, and is provided to the lower address terminal AL of the ROM 25 as a signal CN. Thus, the sampling data SD of the tone signal sampled at 8 kHz is sequentially read from the ROM 25 and supplied to the DAC 26. The sampling data SD is converted into an analog voltage by the DAC 26 and output from the output terminal 27 as an audio signal AS.

[0008]

However, the conventional voice processing board 20 has the following problems. That is, the sampling data SD such as a tone signal is
Since it is necessary to store the tone signal in M25, an arbitrary tone signal cannot be output. In addition, there is a problem that the capacity of the ROM 25 increases as the number of types of tone signals to be output increases.

An object of the present invention is to solve the problems of the prior art and to provide an audio processing board capable of outputting an arbitrary tone signal without increasing the circuit scale.

[0010]

According to the present invention, there is provided an audio processing board which is mounted in an expansion slot of a computer and outputs an audio signal. An interface means for receiving an output instruction including one or more output frequency components and an output level; and an operation for calculating an instantaneous value of an output signal based on the received output instruction at each timing of a sampling signal given at a fixed period. And digital-to-analog conversion means for converting the instantaneous value of the output signal calculated by the calculation means into an analog audio signal and outputting the signal.

According to the present invention, since the audio processing board is configured as described above, the following operations are performed. When an output instruction is given from the computer to the audio processing board mounted on the expansion slot, the output instruction is received by the interface means. The received output instruction is decoded by the arithmetic means, and an instantaneous value of the output signal is calculated at each timing of the sampling signal based on the specified one or more output frequency components and the output level. The calculated instantaneous value of the output signal is converted into an analog audio signal by digital / analog conversion means and output.

[0012]

FIG. 1 is a block diagram of a voice processing board according to an embodiment of the present invention. Elements common to those in FIG. 2 are denoted by the same reference numerals. The audio processing board 20A has an interface unit (for example, I / F) 21 for connecting to a computer (for example, PC) 10 via an expansion slot. The I / F 21 is connected to, for example, a CPU, a ROM in which a processing program is stored, and a calculation means (for example, a calculation processing unit) 28 including a RAM for temporarily storing data of a calculation process. . The arithmetic processing unit 28 includes a timing circuit 2
3 is connected, and the timing circuit 23 supplies a clock signal CK as a reference for operation and a sampling signal SS as an output timing of the audio signal AS.

The arithmetic processing unit 28 receives an I / F from the PC 10 side.
21 is decoded, and sampling data SD of the tone signal of the designated frequency is
The calculation is performed at each timing of the sampling signal SS and is sequentially output. The output side of the arithmetic processing unit 28 is connected to the input side of a digital / analog conversion means (for example, DAC) 26. The output side of the DAC 26 is connected to an output terminal 27, from which an audio signal AS is output.

Next, the operation of FIG. 1 will be described. When a command CD is given from the PC 10, the command CD
Is received by the I / F 21 and passed to the arithmetic processing unit 28.
In the arithmetic processing unit 28, the given command CD is decoded, and output instructions of each output frequency component and output level constituting the audio signal AS to be output are extracted.

Further, in the arithmetic processing unit 28, for example, 8k
Hz (ie, at each timing of the sampling signal SS)
At a period of 125 μs), the instantaneous value of the signal waveform of each output frequency component of the extracted output instruction is calculated. Further, the sum of the instantaneous values of each signal waveform is calculated by the arithmetic processing unit 28 and output as sampling data SD. The sampling data SD is supplied to the DAC 26, converted into an analog voltage, and output from the output terminal 27 as an audio signal AS.

Here, an example of a calculation method in the calculation processing unit 28 will be described. (Example 1) When the output frequency is f0 [Hz] and the output level is 1, and the frequency of the sampling signal SS is fs (where fs> 2f0) [Hz], n (where n is an integer) ) Sampling data S of the result of the second calculation
D1 (n) is as follows. SD1 (n) = sin (2πnf0 / fs)

(Example 2) When the output frequency is f0, f1 [H
z], when the output level of each tone is A ₀ and A ₁ respectively, and the frequency of the sampling signal SS is fs (however, fs> 2f0, 2f1) [Hz], the n-th calculation result Sampling data SD2
(N) is as follows. _{SD2 (n) = A 0 sin} (2πnf0 / fs) + A 1
sin (2πnf1 / fs)

Similarly, when the output frequency is f0, f1,.
In multitone m [Hz], the output level of each _{A 0,} A 1 of each tone, ... in the case of _{A m,} n-th calculation result of the sampling data SDm (n) is as follows. SDm (n) = ΣA _i sin (2πnfi / fs)

(Example 3) The output frequency f0 [Hz] is set to fa.
(However, when amplitude modulation is performed with a modulation signal of fa << f0] [Hz], the sampling data SDa of the n-th calculation result
(N) is as follows. SDa (n) = sin (2πnfa / fs) sin (2
πnf0 / fs)

As described above, the audio processing board 20A of the present embodiment includes the arithmetic processing unit 28 that calculates the instantaneous value of the sampling data SD based on the command CD received from the PC 10, and converts the sampling data SD into analog data. It has a DAC 26 that converts it into an audio signal AS and outputs it. Thereby, there is an advantage that an arbitrary tone signal can be output without increasing the circuit scale.

The present invention is not limited to the above embodiment, but can be variously modified. For example, there are the following modifications (a) to (c). (A) The present invention is not limited to the audio signals of Examples 1 to 3, but can be applied to any audio signal as long as it can be calculated.

(B) In Examples 1 to 3, the calculation method has been described on the assumption that the DAC 26 has a linear characteristic.
For example, D with a conversion rule such as μ-law or A-law
It is also applicable to AC. However, in that case, the sampling data SD output from the arithmetic processing unit 28 is
It is necessary to set the value according to the conversion rule on the DAC 26 side.

(C) The frequency of the sampling signal SS is not limited to 8 kHz. Audio signal AS to be output
If the frequency is at least twice as high as the highest frequency component, the desired audio signal AS can be output.

[0024]

As described above in detail, according to the present invention, there is provided an arithmetic means for calculating an instantaneous value of an output signal at each timing of a sampling signal based on an output instruction received from a computer, and the output signal. Digital-to-analog conversion means for converting the instantaneous value to an analog audio signal and outputting the signal. This has the effect that an arbitrary tone signal can be output without increasing the circuit scale.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an audio processing board according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating an example of a conventional voice processing board.

[Explanation of symbols]

 Reference Signs List 10 PC (personal computer) 20A sound processing board 21 I / F (bus interface) 23 timing circuit 26 DAC (digital / analog converter) 28 arithmetic processing unit

Claims (1)

[Claims] 1. An audio processing board mounted on an expansion slot of a computer and outputting an audio signal, comprising:
An interface means for receiving an output instruction including one or more output frequency components and an output level; and an operation for calculating an instantaneous value of the output signal based on the received output instruction at each timing of a sampling signal given at a constant period. Means for converting an instantaneous value of the output signal calculated by the arithmetic means into an analog audio signal and outputting the analog audio signal.