JPH05291981A - Digital signal processor - Google Patents

Abstract

PURPOSE:To make a signal with a small bit number by dividing an input analog signal into an adjusted output signal with a small dynamic range and a detection signal to be converted into the 1st and 2nd digital signals through A/D conversion. CONSTITUTION:An input analog signal S1 is divided into a compression analog signal S3 with a small dynamic range and a detection signal S2 based on a detection signal S2 detected from an input analog signal S1. Then, the signals S3 and S2 are converted into a compression digital signal S5 and a coefficient digital signal S4 by means of the 1st and 2nd A/D conversion means 8 and 9. Thus, the input analog signal S1 can be converted into a digital signal by means of the A/D conversion means 8 and 9 having the remarkably small resolution.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems (FIGS. 1 and 3) Action (FIG. 2) Example (FIGS. 1 to 3)

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal processing device, and is suitable for application to, for example, a device for processing a digital signal obtained by converting an analog signal whose dynamic range varies greatly.

[0003]

2. Description of the Related Art Conventionally, a lot of raw information in the natural world and social life is generated as analog signals, but digital signals are used for recording and transmitting information because of its excellent calculation accuracy and reproducibility in signal processing. Widely used.

[0004]

By the way, in order to improve calculation accuracy and reproducibility in signal processing using these digital signals, it is necessary to convert the original information into digital signals as faithfully as possible.

Therefore, it is necessary to use an analog / digital conversion circuit or a digital / analog conversion circuit having a high bit resolution, which requires a high level of technology, and a technical problem in the signal processing circuit increases rapidly. Atsuta

For example, when an analog signal having a wide dynamic range such as a voice signal is converted into a digital signal, the dynamic range of the voice signal which is the original information is 1
Since it is about 00 [dB] to 120 [dB], it can be used as an analog / digital conversion circuit or digital / analog conversion circuit.
A resolution of 7 to 20 bits was required.

The present invention has been made in consideration of the above points, and uses a low-resolution analog / digital conversion circuit or digital / analog conversion circuit that has few technical problems and achieves a much lower data rate than the conventional one. An object of the present invention is to propose a digital signal processing device capable of executing processing such as recording and transmitting information.

[0008]

In order to solve such a problem, according to the present invention, an analog / digital conversion processing unit 2 for sequentially converting an input analog signal S1 into a digital signal and a digital signal for sequentially reproducing an analog signal S7. In the digital signal processing device 1 having the digital / analog conversion processing unit 4, the analog / digital conversion processing unit 2 includes a signal level detection unit 7 that sequentially detects the average signal level of the input analog signal S1, and a signal level detection unit. The first signal amplitude control means 6 for expanding or compressing the signal amplitude of the input analog signal based on the detection signal S2 output from 7 and the signal level detecting means 7 and the first signal amplitude adjusting means 6 Output detection signal S
2 and the compressed analog signal S3 are converted into a coefficient digital signal S5 and a compressed digital signal S4, respectively, and first and second analog / digital conversion means 9 and 8 are provided, and the digital / analog conversion processing unit 4 includes a compressed digital signal. The digital / analog conversion means 10 for sequentially converting the signal S4 into a reproduced analog signal S6 and the reproduced analog signal S6 are input, and the signal amplitude of the reproduced analog signal S6 is compressed or expanded based on the coefficient digital signal S5. Second signal amplitude adjusting means 11 for reproducing S1
And have it.

[0009]

The input analog signal S1 is divided into a compressed analog signal S3 and a detection signal S2 whose dynamic range is narrowed based on the detection signal S2 detected from the input analog signal S1, and the compressed analog signal S3 and the detection are performed. By converting the signal S2 into the compressed digital signal S5 and the coefficient digital signal S4 by the first and second analog / digital conversion means 8 and 9, respectively, the analog / digital signal having a remarkably smaller resolution than the conventional one can be obtained. The input analog signal S1 can be converted into a digital signal by the digital converting means 8 and 9. Also, the number of bits of the digital signal converted by this is much smaller than that of the conventional one.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a digital signal transmission device as a whole, which converts sequentially input analog signals into a digital signal in a transmission device 2 and transmits the digital signal to a reception device 4 via a transmission line 3. It is done like this.

Here, the transmitter 2 receives the input analog signal S
1 is input to the automatic gain adjustment amplifier 6 and the average level detection circuit 7 via the input amplifier 5 having a buffer amplifier configuration. The automatic gain adjustment amplifier 6 adjusts and outputs the dynamic range of the input analog signal S1. There is.

That is, the automatic gain adjustment amplifier 6 receives the average level detection signal S2 input from the average level detection circuit 7.
The amplitude of the input analog signal S1 is adjusted based on the above, and the output analog signal S3 having the adjusted signal amplitude is supplied to the analog / digital conversion circuit 8.

Incidentally, the automatic gain adjustment amplifier 6 reduces the gain and compresses the amplitude when the amplitude of the input analog signal S1 is large, and increases the gain and expands the amplitude when the amplitude is small and outputs the output. It is designed to do.

On the other hand, the average level detection circuit 7 has an input analog signal S1 whose dynamic range changes every moment.
The average signal level of the input analog signal S1 is detected, and the average signal level is supplied to the automatic gain adjustment amplifier 6 and the analog / digital conversion circuit 9 as the average level detection signal S2.

Further, the analog / digital conversion circuits 8 and 9 have an output analog signal S3 and an average level detection signal S.
2 is converted into 8-bit digital data and 4-bit digital data, and the compressed data S4 and the compression coefficient data S5 are output to the transmission line 3.

On the other hand, the receiving device 4 converts the compressed data S4 input through the transmission line 3 into the received analog signal S6 again by the digital / analog conversion circuit 10 and inputs it to the digital variable amplifier 11. Has been done.

When the compression coefficient data S5 is input through the transmission line 3, the digital variable amplifier 11 restores the signal amplitude of the received analog signal S6 by a processing procedure reverse to that of the automatic gain adjustment amplifier 6, and reproduces the reproduced analog signal. The output is made as S7.

In the above configuration, the digital signal transmission apparatus 1 inputs the audio signal whose dynamic range changes drastically as shown in FIG. 2 (A).
Is supplied to the average level detection circuit 7 via the input amplifier 5, and the average signal level of the input analog signal S1 is sequentially detected.

Here, since the dynamic range of the input analog signal S1 becomes smaller in the order of the periods T1, T2 and T3, the average level detecting circuit 7 outputs the average level detecting signal S2 which draws a downward-sloping curve to the automatic gain adjusting circuit 6 and the automatic gain adjusting circuit 6. analog/
It is supplied to the digital conversion circuit 9 (FIG. 2 (C)).

At this time, when the automatic gain adjusting circuit 6 receives the average level detection signal S2, the dynamic range is wide in the period T1, so that the input analog signal S1 is compressed to narrow the band and output to the analog / digital conversion circuit 8. (FIG. 2 (B)).

In the following periods T2 and T3, the automatic gain adjusting circuit 6 expands the waveform in contrast to the period T1 because the dynamic range of the input analog signal S1 becomes narrower in order, and outputs it to the analog / digital conversion circuit 8.

As a result, the digital signal transmission device 1 is
Two kinds of signals representing the average signal level and the shape of the signal waveform can be converted from the input analog signal S1 into 4-bit and 8-bit digital data by the analog / digital conversion circuits 9 and 8, and the input analog signal S1 Can be converted into a smaller number of bits as compared with the case of converting directly into a digital signal.

On the side of the receiving device 4, the 8-bit compressed data S4 input via the transmission line 3 is converted into an analog signal via the digital / analog conversion circuit 10, and then the dynamics are calculated based on the compression coefficient data S5. When the range is expanded or compressed, a reproduced analog signal S7 is output from the digital variable amplifier 11 to reproduce the original signal waveform (FIG. 2 (D)).

According to the above configuration, the input analog signal S
1 is divided into two signals of the compressed data S4 and the compression coefficient data S5 and transmitted.
A wide dynamic range signal requiring data of up to 20 bits can be transmitted at a total of 12 bits, and the transmission rate can be further improved as compared with the conventional case.

In the above embodiment, the case where the reproduced analog signal S7 is reproduced from the received analog signal S6 by using the digital variable amplifier 11 has been described, but the present invention is not limited to this, and as shown in FIG. The present invention can be widely applied to the case where the reproduced analog signal S7 is reproduced from the received analog signal S6 by using the analog variable amplifier 21.

In this case, the digital signal transmission device 20 converts the compression coefficient data S5 into the digital / analog conversion circuit 2.
The reproduction analog signal S7 may be reproduced by converting it into the compression coefficient signal S21 via 2 and multiplying the reception analog signal S6 by the compression coefficient signal S21.

In the above embodiment, the case where the compressed data S4 and the compression coefficient data S5 are transmitted to the receiving device 4 via the transmission line 3 has been described, but the present invention is not limited to this, and is recorded in a recording medium. The present invention can also be applied to the case of inputting to a digital signal processing circuit or the like, and in this case, the recording density and the processing speed can be further improved as compared with the conventional case.

Further, in the above-mentioned embodiment, the case where the audio signal is inputted as the input analog signal S1 has been described, but the present invention is not limited to this, and the case where the video signal is inputted or the seismic wave having the log scale signal waveform is inputted. It is particularly effective in the case of a signal that can reproduce a rough signal waveform.

Further, in the above-mentioned embodiment, the case where the output analog signal S3 is converted into 8-bit digital data and the compression coefficient data S5 is converted into 4-bit digital data has been described, but the present invention is not limited to this. , It can also be applied when allocating other bit numbers.

[0031]

As described above, according to the present invention, the input analog signal is divided into the adjusted output signal and the detection signal having the narrowed dynamic range based on the detection signal detected from the input analog signal, The adjustment output signal and the detection signal are first converted by analog / digital conversion.
And the second digital signal, the input analog signal can be converted into the digital signal by the analog / digital conversion means having a remarkably smaller resolution than the conventional one, and also compared with the conventional one. It can be converted into a digital signal with a small number of bits.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digital signal processing device according to the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation.

FIG. 3 is a block diagram for explaining another embodiment.

[Explanation of symbols]

1, 20 ... Digital signal transmission device, 2 ... Transmission device, 3 ... Transmission line, 4 ... Reception device, 5 ... Input amplifier, 6 ... Automatic gain adjustment amplifier, 7 ... Average level detection circuit, 8, 9 ... Analog / digital conversion circuit, 1
0,22 …… Digital / analog converter, 11 ……
Digital variable amplifier, 21 ... Analog variable amplifier.

Claims (2)

[Claims] 1. A digital signal processing apparatus comprising: an analog / digital conversion processing unit for sequentially converting an input analog signal into a digital signal; and a digital / analog conversion processing unit for sequentially converting the digital signal into a reproduced analog signal. The analog / digital conversion processing unit enlarges the signal amplitude of the input analog signal based on the detection signal output from the signal level detection unit and the signal level detection unit that sequentially detects the average signal level of the input analog signal. First signal amplitude control means for compressing and outputting, and the detection signal and the compressed analog signal output from the signal level detection means and the first signal amplitude control means are converted into a coefficient digital signal and a compressed digital signal, respectively. The first and second analog / digital conversion means The digital / analog conversion processing unit receives the digital / analog conversion means for sequentially converting the compressed digital signal into a reproduced analog signal and the reproduced analog signal, and outputs the reproduced analog signal based on the coefficient digital signal. A digital signal processing device comprising: a second signal amplitude control means for compressing or expanding a signal amplitude to reproduce the input analog signal. 2. A digital signal processing apparatus comprising: an analog / digital conversion processing unit for sequentially converting an input analog signal into a digital signal; and a digital / analog conversion processing unit for sequentially converting the digital signal into a reproduced analog signal. The analog / digital conversion processing unit enlarges the signal amplitude of the input analog signal based on the detection signal output from the signal level detection unit and the signal level detection unit that sequentially detects the average signal level of the input analog signal. First signal amplitude control means for compressing and outputting, and the detection signal and the compressed analog signal output from the signal level detection means and the first signal amplitude control means, respectively, into a coefficient digital signal and a compressed digital signal, respectively. First and second analog / digital conversion means for converting The digital / analog conversion processing section has a first digital / analog conversion means for sequentially converting the compressed digital signal into a reproduced analog signal, and a second digital / analog conversion means for sequentially converting the coefficient digital signal into a coefficient analog signal. Digital / analog conversion means, second signal amplitude control means for inputting the reproduced analog signal, compressing or expanding the signal amplitude of the reproduced analog signal based on the coefficient analog signal, and reproducing the input analog signal A digital signal processing device having.