JPH07319499A - Voice signal recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide an automatic answering telephone using a semiconductor memory and a facsimile equipment with an automatic answering telephone function capable of making reproduced sound volumes at every message uniform without using an analog AGC circuit. CONSTITUTION:An analog/digital converter 1a quantizes a voice signal to make it voice data. A level calculating unit 2b calculates levels of voice data. A RAM 3 stores voice data encoded by a voice encoder 2a and also data of levels. A voice decoder 2c elongates and decodes encoded voice data read out from the RAM 3. An amplifier 2d shifts levels of voice data based on levels read out from the RAM 3. A digital/analog converter 1b restores voice data to an analog voice signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio signal recording / reproducing apparatus using a semiconductor memory, which is used in an answering machine, a facsimile machine with an answering machine function, and the like. The present invention relates to an audio signal recording / reproducing device which is made to be the same in each case to make it easier to hear.

[0002]

2. Description of the Related Art In recent years, answering machines having a semiconductor memory instead of a cassette tape as a recording medium have been commercially available. The adoption of the semiconductor memory is excellent in reliability because no mechanical structure is required, and it is convenient in order to make the answering machine multifunctional. Further, due to the progress of voice compression coding technology, more messages can be recorded with less memory capacity.

By the way, the signal level of a message recorded by an answering machine varies depending on various factors. The signal level varies depending on not only the loudness of the speaker's voice but also the gain of the amplifier of the speech network of the other party's telephone, the performance of the central office switching equipment, the length of the line between the central office switching equipment and the answering machine. If there is such a change in the signal level, the volume reproduced for each message will be different, making it difficult for the operator to hear.

Conventionally, AGC (Automatic Gain Control) has been used as a means for solving such a variation in the signal level of a message.
There is a method of using a circuit to make the level of a recorded audio signal uniform. FIG. 3 shows a recording / reproducing apparatus provided with such an AGC circuit.

Reference numeral 11a denotes an analog / digital converter, which converts an analog voice signal at a predetermined sampling cycle.
For example, it is converted into an 8-bit digital signal. An encoder 12b compresses the audio data digitized by an appropriate compression encoding method. The compressed audio data is stored in the semiconductor memory (RAM) 13.

On the other hand, 12c is a speech decoder. The audio decoder 12c reads the audio data stored in the semiconductor memory 13 and decompresses the read data. The decompressed and decoded audio signal data is restored to an analog audio signal by the digital / analog converter 11b. The analog voice signal is converted into voice by a speaker (not shown) and enters the ear of the operator.

The AGC circuit 15 enters in front of the analog / digital converter 11a and adjusts its gain so that the level of the analog audio signal becomes uniform. That is,
The AGC circuit 15 is a typical analog circuit, and has a configuration in which, for example, an audio signal is integrated by an integrator and the gain of the amplifier is adjusted based on the integrated value.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the circuit, the tracking of the gain of the amplifier has some delay with respect to the fluctuation of the audio signal level. That is, since the delay is generated in the integrator, the tracking of the gain of the amplifier is delayed accordingly. Then, there occurs a section in which the level of the audio signal is not appropriate.

Further, the voice recording / reproducing circuit shown in FIG. 3 is constituted by a digital circuit such as a digital signal processor (hereinafter referred to as DSP), but it is necessary to provide an analog AGC circuit 15 outside the DSP. Therefore, there is a problem that the number of parts increases and the cost of the device also rises.

The present invention has been made in view of the above, and an object of the present invention is to provide an audio signal recording / reproducing apparatus which does not use an external analog AGC circuit and can reduce the cost of the apparatus.

[0011]

In order to solve the above problems, an audio signal recording / reproducing apparatus according to a first aspect of the present invention includes an encoding / decoding means for encoding / decoding an audio signal and an encoding / decoding means for encoding / decoding the audio signal. In a voice signal recording / reproducing apparatus provided with a storage means for storing voice data, a level detecting means for detecting the level of the voice signal during recording, and a level of the voice signal decoded based on the detected level during playback. And a level adjusting means for adjusting.

According to a second aspect of the present invention, in the first aspect of the invention, the analog / digital converting means for converting an analog voice signal into a digital signal and outputting the digital signal to the encoding / decoding means, and the decoding by the code / decoding means. And a digital / analog conversion means for converting the generated digital signal into an analog voice signal.

According to a third aspect of the present invention, in the second aspect, the level detecting means detects two or more peak values from the digital signal from the analog / digital converting means,
Determine the average value of these peak values as level data,
The voice data is stored in the storage means.

According to a fourth aspect of the present invention, in the second or third aspect of the invention, the level adjusting means reads the level stored in the storage means at the time of reproduction, and adjusts the audio data decoded based on the level. And output to the digital / analog conversion means.

[0015]

According to the invention of claim 1, the level of the recorded audio signal is detected and stored together with the encoded audio data, and the size of the audio data decoded during reproduction is stored. The level data is adjusted to make the reproduced audio signal uniform in size. Unlike the case where an analog AGC circuit is used at the time of recording, since there is no time delay in adjusting the level of the audio data, the audio signal is reproduced at an appropriate level during reproduction.

According to a second aspect of the present invention, the invention of the first aspect can be realized by digital signal processing.
The present invention can be easily implemented by a digital circuit such as P.

According to the third aspect of the invention, the peak value of the quantized audio data is detected as a method of detecting the level of the audio signal. By applying this peak value, the peak value of the reproduced audio signal can be set to a predetermined value, and the levels of the audio signal can be made uniform.

According to a fourth aspect of the present invention, the adjustment value is determined based on the level data of the detected voice signal, and the decoded voice signal is digitally multiplied by this adjustment value so that the levels of the voice signal become uniform. To adjust.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram illustrating a circuit configuration of an audio signal recording / reproducing apparatus according to an embodiment. The audio signal recording / reproducing apparatus according to the embodiment is roughly composed of an analog front end 1, a digital signal processing unit 2, and a random access memory (hereinafter referred to as RAM) 3.

The analog front end 1 is analog /
Digital converter 1a and digital / analog converter 1b
Is included. Further, the digital signal processing unit 2 includes a level calculation circuit 2a, a voice encoding circuit 2b, and a voice decoding circuit 2
c, and amplifier 2d.

The analog / digital converter 1a quantizes the analog audio signal on the signal line 4a in a predetermined cycle.
The number of bits for this quantization is a fixed number of about 8 to 10. The voice data of the analog / digital converter 1a is output to the voice encoding circuit 2b and the level calculation circuit 2a.

The voice encoding circuit 2b compresses voice data by an appropriate method to reduce the data amount. Various methods such as PARCOR and CELP have been proposed as such methods, and an appropriate method may be selected according to the purpose and price of the apparatus. The encoded voice data output from the voice encoding circuit 2b is stored in the RAM 3.

On the other hand, the level calculation circuit 2a detects the peak value from the audio data. This peak is detected by detecting the peak value P within the recording period as shown in FIG.
These average values (Pm = (ΣPi) / n) are stored as level data in the RAM 3 together with the encoded voice data.

The voice decoding circuit 2c reads the encoded voice data from the RAM 3 and decompresses it. Voice decoding circuit 2c
The audio data from is input to the amplifier 2d. The amplifier 2d is a multiplier, which multiplies the input by an adjustment value based on the level data stored in the RAM 3.

As the adjustment value, the simplest value (F / Pm) is used so that the average Pm of the peak values of the audio data becomes the optimum transmission level F. Of course, the method of calculating the adjustment value is not limited to this, and another method can be adopted as appropriate.

The level-adjusted audio data output from the amplifier 2d is converted into an analog signal by the digital / analog converter 1b and output from the signal line 4b to the outside. Since the level of this analog audio signal is adjusted by the amplifier 2d, the level is uniform for each recording, which makes it easy for the operator to hear.

The digital signal processing section 2 may be composed of dedicated hardware or a DSP. The RAM 3 is the digital signal processing unit 2 as in the embodiment.
It may be externally attached, or dedicated hardware or DSP
It may be built in. Further, it is also possible to connect other microcomputer application equipment without directly connecting the RAM 3 to the digital signal processing unit 2 and store the encoded voice data and the level data in a storage device such as a RAM or a hard disk of the microcomputer. it can.

Regarding the calculation of the level, peaks are calculated and stored for each constant period during one recording, and each peak value is read out for each period during reproduction.
The level of the audio signal may be adjusted. By doing so, it is possible to deal with the fluctuation of the audio signal level during one recording.

[0029]

As described above, the invention of claim 1 has an advantage that the audio signal level can be made uniform without using an analog external AGC circuit. Also,
According to the second aspect of the invention, since the audio signal level is made uniform by digital signal processing, the present invention can be realized by a digital circuit such as a DSP.

Further, according to the third aspect of the present invention, since the audio signal level is adjusted based on the average value of the peaks, it is possible to properly equalize the audio signal level. In addition, according to the invention of claim 4, the adjustment of the level of the audio data can be easily realized by digital multiplication.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a circuit configuration of an audio signal recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining peak detection of an audio signal recording / playback device according to an embodiment.

FIG. 3 is a block diagram illustrating a circuit configuration of a conventional audio signal recording / reproducing device.

[Explanation of symbols]

 1 analog front end 1a analog / digital converter 1b digital / analog converter 2 digital signal processing unit 2a level calculation circuit 2b voice encoding circuit 2c voice decoding circuit 2d amplifier 3 RAM

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 13, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

Reference numeral 11a denotes an analog / digital converter, which converts an analog voice signal at a predetermined sampling cycle.
For example, it is converted into an 8-bit digital signal. 12b is sound
This is a voice encoding circuit , which compresses voice data digitized by an appropriate compression encoding method. The compressed audio data is stored in the semiconductor memory (RAM) 13.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

On the other hand, 12c is a speech decoding circuit . The voice decoding circuit 12c reads the voice data stored in the semiconductor memory 13 and decompresses the read data.
The decompressed and decoded audio signal data is restored to an analog audio signal by the digital / analog converter 11b. The analog voice signal is converted into voice by a speaker (not shown) and enters the ear of the operator.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The AGC circuit 15 enters in front of the analog / digital converter 11a and adjusts its gain so that the level of the analog audio signal becomes uniform. That is,
The AGC circuit 15 typically includes an integrator, and the audio signal is integrated by the integrator and the gain of the amplifier is adjusted based on the integrated value.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Delete

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010] The present invention has been made in view of the above, AG
Eliminate the influence of the delay of the C circuit and adjust the level of the audio signal.
The purpose is to provide a proper audio signal recording / reproducing device.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

[0029]

As described in the foregoing, a first aspect of the invention, without Rukoto affected delay of the AGC circuit has the advantage of equalizing the speech signal level. Further, according to the invention of claim 2, since the audio signal level is made uniform by the digital signal processing, the present invention can be realized by a digital circuit such as a DSP.

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (4)

[Claims] 1. An audio signal recording / reproducing apparatus comprising an encoding / decoding means for encoding / decoding an audio signal and a storage means for storing audio data encoded by the encoding / decoding means. An audio signal recording / reproducing apparatus comprising: a level detecting means for detecting a signal level; and a level adjusting means for adjusting a level of a decoded audio signal based on the detected level during reproduction. 2. An analog / digital converting means for converting an analog voice signal into a digital signal and outputting it to the encoding / decoding means, and a digital / digital converting means for converting the digital signal decoded by the encoding / decoding means into an analog voice signal. The audio signal recording / reproducing apparatus according to claim 1, further comprising an analog converting means. 3. The level detecting means detects two or more peak values from the digital signal from the analog / digital converting means, determines the average value of these peak values as level data, and stores the voice data in the storing means. The audio signal recording / reproducing device according to claim 2, which is stored together with the audio signal recording / reproducing device. 4. The level adjusting means reads the level data stored in the storage means during reproduction, multiplies audio data decoded based on the level data by an adjustment value, and causes the digital / analog converting means to perform the multiplication. Claim 2 to output
Alternatively, the audio signal recording / reproducing apparatus according to the item 3.