JPH09200053A - Signal transmission method and device - Google Patents

Abstract

(57) Abstract: Conventionally, when transmitting and recording 1-bit digital data, level information could not be displayed accurately in real time. A CPU 4 of a digital data transmission unit 1
Generates sub-data including level information related to the 1-bit audio data from the blocked data obtained by blocking the 1-bit audio data from the ΣΔ modulator 3 in units of a predetermined number. The multiplexer 5 is a CPU
A digital data string is generated by including the sub data from 4 and the blocked data. The data separating unit 21 of the digital data receiving unit 20 separates the main data and the sub data, which are blocked data, from the digital data string transmitted and recorded by the transmission recording unit 10. The CPU 24, which is a level information detection unit, detects level data from the sub data. The display unit 25 displays the level data as a numerical value, a geometrical display, or an envelope waveform display.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission method and apparatus for recording and transmitting sigma-delta modulated 1-bit digital data.

[0002]

2. Description of the Related Art As a method of digitizing a voice signal, a method called sigma delta (ΣΔ) modulation has also been known. (Journal of Acoustical Society of Japan, Vol. 46, No. 3 (199
0) pp. 251-257, "AD / DA converter and digital filter (Yoshio Yamazaki)", etc.).

The 1-bit audio data obtained by this ΣΔ modulation has a sampling frequency of 44.4 compared to multi-bit audio data having a sampling frequency of 44.1 KHz and a data word length of 16 bits, which has been used in conventional digital audio. It has a very high sampling frequency and a short data word length such that the data word length is 1 bit at 64 times 1 KHz, and is characterized by a wide transmittable frequency band. Even with a 1-bit signal by ΣΔ modulation, a high dynamic range can be secured in an audio band that is low with respect to an oversampling frequency of 64 times.
Utilizing this feature, it can be applied to high-quality sound recorders and data transmission.

This ΣΔ modulation circuit itself is not a new technology in particular, its circuit configuration is suitable for integration into an IC, and the accuracy of A / D conversion can be obtained relatively easily. It is often used inside.

The ΣΔ modulated signal can be returned to an analog audio signal by passing through a simple analog low pass filter.

[0006]

By the way, when transmitting / receiving, that is, transmitting the above-mentioned 1-bit audio data which is ΣΔ-modulated, unlike the conventional transmission in the case of multi-bit audio data, it is difficult to display the level information as it is. there were. Here, the level information is information indicating the output level of 1-bit audio data.

As a level display method for displaying the level information, down-sampling processing is performed on the 1-bit audio data to convert it into multi-bit audio data, and then the multi-bit audio data is used as level information (data) and numerical values are displayed. There is a method of performing level display by display, geometric display or envelope waveform display.
This method is embodied in a digital data transceiver 50 as shown in FIG.

In FIG. 6, an analog audio signal supplied from an input terminal 51 is converted into 1-bit audio data by a ΣΔ modulator 52, which is transmitted by a transmission recording section 50 which is a recording medium such as a compact disc and digitally transmitted. The data reception unit 54 is reached.

In the digital data receiving section 54, the 1-bit audio data is down-sampled by the decimation filter 57 to be level information. This level information has, for example, a sampling frequency of 4
The multi-bit data is 4.1 KHz and has a word length of 16 bits, and is supplied to the display unit 58 and displayed as a level. On the other hand, the 1-bit audio data is the D / A converter 5
The analog audio signal is also supplied to the output terminal 5 and output from the output terminal 56.

However, when displaying the level information as described above in real time, the number of taps of the decimation filter 57 and the word length of the filter coefficient are limited due to the limitation of the processing time, and an accurate level display cannot be expected. .

Further, if an attempt is made to display an accurate level, the number of taps of the decimation filter 57 and the word length of the filter coefficient become enormous, which makes it difficult to display the level in real time.

Further, if an accurate display is performed in real time, the circuit size of the decimation filter 57 becomes large and complicated, which is also disadvantageous in terms of cost.

The present invention has been made in view of the above circumstances, and provides a signal transmission method and apparatus capable of displaying level information accurately in real time when transmitting and recording 1-bit digital data. With the goal.

[0014]

In order to solve the above-mentioned problems, a signal transmission method according to the present invention adds level information relating to sigma-delta modulated 1-bit digital data to the 1-bit digital data. The level information is transmitted and reproduced, and the level information is detected and the level is displayed.

In the signal transmission method according to the present invention, the 1-bit digital data that has been sigma-delta modulated is divided into blocks by a predetermined number, and the obtained block data is obtained by downsampling in the level information generating step. Level information is added to the block data in a sub data format and transmitted and recorded, and on the reproducing side, a data separation processing step,
Also, the level information may be extracted by the level information detecting step.

Further, the signal transmission device according to the present invention is such that the level obtained by down-sampling processing by the level information generating means from the block data obtained by dividing the sigma-delta modulated 1-bit digital data into a predetermined number of blocks. Information is added to the block data in a sub-data format and transmitted and recorded. On the reproducing side, the data separation processing means and the level information detecting means extract the level information and display the level.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a signal transmission method and apparatus according to the present invention will be described below with reference to the drawings.

As shown in FIG. 1, this embodiment is a digital data transmitter / receiver 30 comprising a digital data transmitter 1, a transmission recorder 10 and a digital data receiver 20.

The digital data transmitter / receiver 30 includes
The 1-bit audio data that has been sigma delta (ΣΔ) modulated by the digital data transmission unit 1 is transmitted and recorded via the transmission recording unit 10 and received by the digital data reception unit 20. Level information is generated from the bit audio data, and the level information is transmitted and recorded by the transmission recording unit 10 together with the 1-bit audio data. Further, the digital data receiving section 20 separates the level information from the 1-bit audio data and displays the level information in a numerical display, a geometrical display, an envelope waveform display, or the like.

The digital data transmitter 1 has an input terminal 2
From the analog audio signal supplied from the ΣΔ modulator 3 and 1-bit audio data from the ΣΔ modulator 3 is divided into blocks by a predetermined number of units. ) From the central processing unit (C) for generating sub data including level information related to the 1-bit audio data.
PU) 4 and a multiplexer 5 for generating a digital data string including the sub data from the CPU 4 and the blocked data.

As shown in FIG. 2, the CPU 4 performs a downsampling process on the blocked data to generate the level information, a downsampling processing unit 6, and a fundamental frequency supplied from the level data and the input terminal 7. The sub-data generating unit 8 generates sub-data based on the information and the emphasis information.

The downsampling processing section 6 is composed of, for example, a decimation filter. The generation of level data by the downsampling processing unit 6 is
Since the processing is performed by the digital data transmission unit 1, it is not necessary to consider the processing method with respect to the limitation of the processing time.

The digital data receiving unit 20 further includes a data separating unit 21 for separating blocked data (main data) and the sub data from the digital data string transmitted and recorded by the transmission recording unit 10, and the main data. D / A converter 22 for converting the analog audio signal into an analog audio signal and outputting it from the output terminal 23, and a level information detection unit (CPU) 24 for detecting level data from the sub data.
And a display unit 25 for displaying the level data by numerical display, geometric display or envelope waveform display.

The multiplexer 5 of the digital data transmission unit 1 synthesizes the block data and the sub data to generate a digital data string composed of, for example, 2048 bytes as shown in FIG. This digital data string has 8
It consists of a byte synchronization signal, 3 bytes of sub data, 2048 bytes of main data (blocked data), and 16 bytes of error correction signal.

Here, in the sub-data, as shown in FIG. 4, 4-bit level information has a 4-bit sampling frequency f.
It is stored with _S , 1-bit emphasis and 15-bit accompanying data.

The input analog signal supplied from the input terminal 2 is ΣΔ modulated to output 1-bit audio data ΣΔ
The modulator 3 is configured as shown in FIG. In FIG. 5, the input analog signal from the input terminal 2 is the adder 1
1 to the integrator 12. The signal from the integrator 12 is supplied to the comparator 13, is compared with the midpoint potential of the input signal, is subjected to 1-bit quantization processing for each sample period, and is output as 1-bit audio data.

The 1-bit audio data, which is the quantized data, is supplied to the 1-sample delay unit 14 and delayed by 1 sample period. This delay data is converted into an analog signal by the 1-bit D / A converter 15 and added to the adder 1
1 and is added to the input analog signal from the input terminal 2. Then, the 1-bit audio data output from the comparator 13 is divided into blocks by a predetermined number unit, and is output to the multiplexer 5 via the output terminal 16 as blocked data.

The 1-bit audio data output from the ΣΔ modulator 3 has a conventional sampling frequency, for example.
Compared to multi-bit data with 44.1kHz and 16-bit data word length, it has a very high sampling frequency and a short data word length (for example, the sampling frequency is 64 times 44.1kHz and the data word length is 1 bit). It features a wide transmission frequency band. In addition, even with 1-bit audio data, a high dynamic range can be ensured in the audio band, which is a low band with respect to the oversampling frequency of 64 times, by the sigma-delta modulation process. Utilizing this feature, it can be applied to high-quality sound recorders and data transmission.

The multiplexer 5 synthesizes, for example, a predetermined number n of the 1-bit audio data, which is the blocked data, with the sub-data shown in FIG. 4 generated by the CPU 4 to generate the digital data string shown in FIG. To generate.

Here, the CP of the digital data transmitter 1
Since the downsampling processing unit 6 in U4 can perform the downsampling processing for generating the level information without being restricted by the processing time, it is not necessary to limit the number of taps or the word length of the filter coefficient, Accurate level information (level data) can be generated.

Then, the digital data string is transmitted to the digital data receiving section 20 by the transmission recording section 10.

The data separating unit 21 of the digital data receiving unit 20 separates the digital data string into main data and sub data. Here, the separated main data is converted into an analog audio signal by the D / A converter 22 and output from the output terminal 23. On the other hand, the separated sub-data is the level information detection unit (CPU) 2
4 and the level information detection unit (CPU) 24 extracts the level data. Then, the level data is supplied to the display unit 25 and displayed as a level by numerical display, geometric display or envelope waveform display.

Therefore, the digital data receiving section 20 can obtain accurate level information only by a simple separation process by the data separating section 21, and can further display the level information in real time.

As described above, the digital data transmitting / receiving apparatus 30 according to the embodiment of the present invention generates the multi-bit accurate level information from the 1-bit audio data by the down-sampling process in the digital data transmitting unit 1, and calculates ΣΔ in advance. After being added to the modulated 1-bit audio data, the transmission / recording unit 10 transmits the data, and the digital data receiving unit 20 separates the main data consisting of 1-bit audio data and the level information by D / Accurate level information of the analog audio signal output from the A converter 22 is displayed in real time on the display unit 25.
Can be displayed with.

The transmission recording unit 10 may be a communication cable or a recording medium such as a magnetic tape and a magneto-optical disk.

[0036]

According to the signal transmission method of the present invention, the level information related to the sigma-delta-modulated 1-bit digital data is added to the 1-bit digital data for transmission, and the level information is detected during reproduction. Since the level is displayed, the level information can be accurately displayed in real time when the 1-bit digital data is transmitted and recorded.

Further, the signal transmission device according to the present invention adds the level information obtained by the level information generating means from the sigma-delta-modulated 1-bit digital data to the 1-bit digital data in a sub-data format for transmission recording. Since the level information is extracted by the data separation processing means and the level information detecting means on the receiving side, the level information can be accurately displayed in real time when the 1-bit digital data is transmitted and recorded.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital data transmitting / receiving apparatus as an embodiment of a signal transmission method and apparatus according to the present invention.

FIG. 2 is a C used in the digital data transmitter / receiver.
It is a block diagram which shows the detailed structure of PU.

FIG. 3 is a format diagram of a digital data string generated by a digital data transmission unit that constitutes the digital data transmission / reception device.

FIG. 4 is a format diagram of sub-data forming the digital data string.

FIG. 5 is a block diagram showing a detailed configuration of a sigma-delta modulation circuit used in the digital data transmission unit.

FIG. 6 is a block diagram showing a schematic configuration of a conventional digital data transmitting / receiving apparatus.

[Description of Codes] 1 Digital Data Transmitter 3 Sigma Delta Modulator 4 Central Arithmetic Processor 5 Multiplexer 10 Transmission Recorder 20 Digital Data Receiver 21 Data Separator 22 D / A Converter 24 Central Arithmetic Processor 25 Display

Claims (5)

[Claims] 1. A signal transmission method for transmitting sigma-delta modulated 1-bit digital data, wherein level information related to the 1-bit digital data is added to the 1-bit digital data and transmitted, and the level information is reproduced at the time of reproduction. A signal transmission method characterized by detecting the level and displaying the level. 2. From the block data obtained by dividing the 1-bit digital data into blocks by a predetermined number,
Including the level information generation step of generating level information related to bit digital data by down-sampling processing, the sub data generation step of generating sub data including the level information, and the sub data and the blocked data. A digital data string generating step of generating a digital data string, a data separating step of receiving the digital data string to separate blocked data and sub-data, and a level information detecting step of detecting level information from the sub-data. The signal transmission method according to claim 1, further comprising: 3. A level information generating means for generating level information related to the 1-bit digital data from blocked data obtained by blocking the sigma-delta modulated 1-bit digital data in units of a predetermined number, and including the level information. Sub data generating means for generating sub data, digital data sequence generating means for generating a digital data sequence including the sub data and the blocked data, and transmission recording means for transmitting and recording the digital data sequence, A signal transmission device comprising: a data separation means for separating the digital data string through the transmission / recording means into blocked data and sub data; and level information detection means for detecting level information from the sub data. . 4. The signal transmission device according to claim 3, wherein the level information detecting means generates the level information by downsampling processing. 5. The signal transmission device according to claim 3, wherein the level information detected by the level information detecting means is displayed on the display means.