JPH05218981A - Voice signal transmitter - Google Patents

Abstract

PURPOSE:To provide the voice signal transmitter in which the scale of the circuit is small and its propagation delay time is small by adopting delta modulation. CONSTITUTION:An analog voice signal is subjected to delta sigma modulation by a delta modulator 102 and 3MHz sampling/quantization to be converted into 1-bit digital signal. The digital signal is converted into an optical signal by an electric/optic converter 103 and sent through an optical fiber 104. A optic/electric converter 105 converts the optical signal from the optical fiber 104 into an electric signal. Then the electric signal is converted into an original analog signal by a delta demodulator 108 via an AC coupling amplifier 106 and a timing extract circuit 107. Since the delta modulator 102 and the delta demodulator 108 are realized with simple circuits, the configuration of the entire transmitter is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice signal transmission device for digitally transmitting an analog voice signal using an optical fiber.

[0002]

2. Description of the Related Art In recent years, there have been active developments of devices capable of digital audio signal processing, such as amplifiers capable of inputting and outputting digital signals and digital audio tape recorders. Along with this, digital audio signal transmission technology for connection between devices has been developed.

Under such circumstances, there is a voice signal transmission apparatus which uses the digital voice signal transmission technique as described above and whose input and output are analog signals and whose transmission is a digital signal. For example, a transmission device applied to a hall sound system or the like.

An example of a conventional audio signal transmission device will be described below. FIG. 8 is a block diagram showing the structure of a conventional audio signal transmission device. In FIG. 8, 80
1, 802 are analog audio signal input terminals, 803, 80
4 is an analog / digital converter, 805 is a multiplex circuit,
Reference numeral 806 is a bi-phase mark encoding circuit, 807 is an electric / optical converter, 808 is an optical fiber, 809 is an optical / electrical converter, 810 is an AC coupling amplifier, 811 is a timing extraction circuit, and 812 is a bi-phase mark composite circuit. , 81
3 is a separation circuit, 814 and 815 are digital / analog converters, and 816 and 817 are analog audio signal output terminals.

The operation of the audio signal transmission apparatus configured as described above will be described below.

Analog voice signal input terminals 801, 802
The analog audio signal input from the
The digital converters 803 and 804 convert the digital audio signals with a sampling frequency of 48 kHz and a quantization bit number of 16 bits. These two channels of digital audio signals are frame processed / multiplexed by a multiplexing circuit 805,
It is converted into a 1-bit serial signal (3.072 Mbps). In the bi-phase mark encoding circuit 806, the output signal of the multiplexing circuit 805 is coded using a 6.144 MHz clock so that the mark rate becomes 50% regardless of the input digital audio signal, and a 1-bit signal is output. Is being output. Bi-phase mark encoding circuit 80
The electrical signal which is the output of No. 6 is converted into an optical signal by the emission intensity modulation by the electrical / optical converter 807, and the optical fiber 808
Is output to. The optical signal transmitted by the optical fiber 808 is converted into an electric signal by the optical / electrical converter 809 and input to the AC coupling amplifier 810. The AC coupling amplifier 810 converts the input electric signal into an electric logic level (T
It is amplified to TL level). The timing extraction circuit 811 extracts the transmission clock component from the output signal of the AC coupling amplifier 810, and discriminates the electrical logic level between “H” and “L” at the timing of this clock. The output signal of the timing extraction circuit 811 is subjected to a decoding process of a biphase mark code in a biphase mark decoding circuit 812 and converted into a serial signal of 3.072 Mbps. In the separation circuit 813, frame detection is performed from the output signal of the biphase mark decoding circuit 812,
A 48 kHz sampling, 16-bit, 2-channel digital audio signal is output. Separation circuit 813
The 2-channel digital audio signal output from
The digital / analog converters 814 and 815 convert the analog audio signals into analog audio signals, which are output to the analog audio signal output terminals 816 and 817, respectively.

In this conventional example, the mark ratio of the transmission data is set to 50%, which is the optical / electrical converter 809.
This is because the output signal of 1 is amplified by the AC coupling amplifier 810. If the mark rate is not 50%,
Since there is a DC component in the transmission data, it is necessary to use a DC coupling circuit configuration to transmit and receive the DC component information so as not to be lost. Further, since an automatic gain control circuit for keeping the output constant according to the increase / decrease of the optical signal is required and the circuit configuration becomes complicated, the mark ratio is set to 50% before the electric / optical conversion is performed. ..

[0008]

However, in the above-mentioned conventional configuration, an analog / digital converter or a digital / analog converter having a large number of quantization bits, and further encoding for making the mark rate of serial data 50%. There is a problem that a circuit and a decoding circuit are required and the circuit scale is large.

Further, since a low sampling frequency of 48 kHz and a large number of quantization bits of 16 bits are used, the time required for digital signal processing for multiplexing / demultiplexing is long, and the mark rate of serial data is 5%.
There is also a problem that the propagation delay time is long because digital signal processing for encoding / decoding to achieve 0% is also required.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an audio signal transmission apparatus in which the circuit scale is reduced and the propagation delay time is reduced.

[0011]

In order to achieve this object, a voice signal transmission apparatus of the present invention comprises: (1) a delta modulator that delta-modulates an analog voice signal and outputs a 1-bit digital signal; The 1-bit signal output from the timing extraction circuit is demodulated by delta modulation to output an analog audio signal.

(2) k pieces (k is 2) that delta-modulates an analog voice signal and outputs a 1-bit digital signal.
(The above integers) delta modulators, k electrical / optical converters that convert the output electrical signals of each of the k delta modulators into optical signals of different wavelengths, and k electrical / optical converters Optical multiplexer that multiplexes the optical signal that is the output of, the optical demultiplexer that demultiplexes the optical signal transmitted by the optical fiber into k kinds of optical signals according to the optical wavelength, and the outputs of the k timing extraction circuits The k-delta demodulators that perform delta modulation demodulation from each of the 1-bit signals and output an analog audio signal are configured.

(3) A delta modulator group consisting of n delta modulators for delta-modulating analog audio signals of n channels (n is an integer of 2 or more) and outputting a 1-bit digital signal, and delta modulation A multiplexer circuit that multiplexes the output signals of the group of devices to output a 1-bit serial electric signal, a separation circuit that separates the 1-bit signal output from the timing extraction circuit into an n-channel signal, and the output of the separation circuit. A delta demodulator group consisting of n delta demodulators that perform delta modulation demodulation from each signal and output an analog audio signal is configured.

(4) A first delta modulator group consisting of m delta modulators for delta-modulating analog audio signals of m channels (m is an integer of 1 or more) and outputting a 1-bit digital electric signal. And a second delta modulator group consisting of m delta modulators for respectively delta-modulating m channel analog audio signals different from the first delta modulator group and outputting a 1-bit digital electric signal. , A first inverter group consisting of m inverters that invert the respective logics of the output signals of the second delta modulator group, an output signal of the first inverter group and an output signal of the first delta modulator group A multiplexing circuit for multiplexing and outputting a 1-bit serial electric signal, and a separation circuit for separating the 1-bit signal output from the timing extraction circuit into a 2m channel signal, From the output signals of the second inverter group consisting of m inverters each of which logically inverts the signal of the m channel corresponding to the channel of which the logic is inverted in the output signal of the separation circuit, Delta modulation demodulation is performed to demodulate delta modulation from each of the first delta demodulator group consisting of n delta demodulators that output an analog audio signal and the non-inverted signal of the output of the separation circuit, And a second delta demodulator group consisting of n delta demodulators that output analog audio signals.

[0015]

According to the present invention, by using the above-described structure, a delta modulator that directly outputs a 1-bit quantized signal and a delta demodulator that performs a demodulation process are used. / Analog converter becomes unnecessary. Further, since the voice signal having no DC component information is subjected to delta modulation, the voice delta modulation signal has a mark rate of almost 50%, and an encoding circuit for making the mark rate of serial data 50%. And a decoding circuit are unnecessary, and the circuit scale is reduced.

Further, since a delta modulation signal of 1-bit quantization is handled at a sampling frequency higher than 48 kHz, the time required for digital signal processing of multiplexing / demultiplexing is small,
Further, since the digital signal processing for encoding / decoding for setting the mark ratio of the serial data to 50% is not necessary, the propagation delay time becomes short.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An audio signal transmission apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an audio signal transmitting apparatus according to the first embodiment of the present invention. In FIG. 1, 101 is an analog audio signal input terminal, 102 is a delta modulator, 103 is an electric / optical converter, 104 is an optical fiber, 105 is an optical / electrical converter, 106 is an AC coupling amplifier, 107 is a timing extraction circuit. , 108 are delta demodulators, and 109 is an analog audio signal output terminal.

The operation of the audio signal transmission apparatus of this embodiment having the above configuration will be described below.

The audio signal input from the analog audio signal input terminal 101 is delta-sigma modulated, which is a kind of delta modulation, by the delta modulator 102 and converted into a 3 MHz sampling / quantized 1-bit digital signal. The electrical signal output from the delta modulator 102 is converted by the electrical / optical converter 103 into an optical signal by emission intensity modulation and output to the optical fiber 104. The optical signal transmitted by the optical fiber 104 is converted into an electric signal by the optical / electrical converter 105 and input to the AC coupling amplifier 106. The AC coupling amplifier 106 amplifies the input electric signal to an electric logic level. Timing extraction circuit 1
In 07, the transmission clock component is extracted from the output signal of the AC coupling amplifier 106, and the electrical logic level "H" or "L" is identified at the timing of this clock. The output signal of the timing extraction circuit 107 is the delta demodulator 10
At 8, demodulation processing of delta sigma modulation is performed and output to the analog audio signal output terminal 109.

Here, the delta modulation will be briefly described. For details, see Chapter 6 of "Electronic Science Series" PCM Communication Technology; Hisashi Kaneko;
p129-141.

Delta modulation is a simple form of the differential PCM system, in which the input signal is compared with the signal obtained by locally demodulating the delta-modulated code, and the error signal is positive or negative at the next sampling time. It is something that will be identified. Delta sigma modulation is one type of such delta modulation.

FIG. 2 is a circuit diagram showing an example of a single integral type delta sigma modulator, and FIG. 3 is a circuit diagram showing an example of a delta sigma demodulator. In FIG. 2, 201 is a modulated signal input terminal, 202 and 205 are capacitors, and 203 and 207.
Is a resistor, 204 is a D flip-flop, 206 is a sampling clock input terminal, and 208 is a delta-sigma modulation signal output terminal. In FIG. 3, 301 is a delta sigma modulation signal input terminal, 302 is a resistor, 303 is a capacitor, and 304 is a delta sigma demodulation signal output terminal.

As shown in FIG. 3, the demodulation of the delta-sigma modulated signal can be realized by a simple integrating circuit. Further, delta-sigma modulation can also be realized by a simple circuit as shown in FIG.
The analog voice signal input from the modulated signal input terminal 201 has a direct current component removed by the capacitor 202,
It is integrated by the integrating circuit composed of the resistor 203 and the capacitor 205. On the other hand, the D flip-flop 204 is a quantizer and outputs a delta-sigma modulated signal.
The inverted output of the D flip-flop 204 is integrated by the integrating circuit including the resistor 207 and the capacitor 205, and is added to the integrated waveform of the analog audio signal. However, since this addition processing uses the inverted output of the D flip-flop 204, it means that the local demodulated signal of the delta-sigma modulated signal and the integrated waveform of the analog audio signal are compared.
This compared error signal is the D of the D flip-flop 204.
The sampling clock cycle identifies whether the potential is higher or lower than the input threshold. The resulting 1-bit digital signal is a delta-sigma modulated signal.

In general, the delta modulator / delta demodulator has a feature that the structure is simple and that a 1-bit quantization requires a higher clock frequency than a normal PCM.

As described above, according to this embodiment, by using the delta modulator 102 and the delta demodulator 108 having a simple circuit configuration, an analog / digital converter or a digital / analog converter having a large number of quantization bits can be obtained. Became unnecessary. In addition, by delta-modulating the audio signal having no DC component, the mark rate is almost 50% at the time of the 1-bit delta-modulated signal, and the mark rate is 50%.
An encoding circuit and a decoding circuit for achieving the above are unnecessary, and the circuit scale can be reduced.

Further, by using the 1-bit quantization delta modulation, direct serial transmission is possible, and the multiplexing / separation processing is not required. Therefore, the circuit scale can be reduced and the propagation delay time from the input of the audio signal to the analog audio signal input terminal 101 to the output of the analog audio signal output terminal 109 can be reduced.

Next, an audio signal transmission device (k = 2) according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram showing the structure of an audio signal transmitting apparatus according to the second embodiment of the present invention. In FIG. 4, 401 and 402 are analog audio signal input terminals and 4
03, 404 are delta modulators, 405, 406 are electric /
Optical converter, 407 is an optical multiplexer, 408 is an optical fiber, 4
09 is an optical demultiplexer, 410 and 411 are optical / electrical converters, 4
12, 413 are AC coupling amplifiers, 414, 415 are timing extraction circuits, 416, 417 are delta demodulators, 41
Reference numerals 8 and 419 are analog audio signal output terminals.

The operation of the audio signal transmission apparatus of this embodiment constructed as above will be described below.

Analog audio signal input terminals 401, 402
The audio signals input from the respective delta modulators 40
Delta-sigma modulation is performed at 3,404, and 3 MHz sampling / quantization is converted into a 1-bit digital signal.
The electric signal output from the delta modulator 403 is converted into an optical signal by the electric / optical converter 405 by light emission intensity modulation by a light source having a wavelength of 1300 nm. The electric signal output from the delta modulator 404 is converted into an optical signal by the electric / optical converter 406 by light emission intensity modulation by a light source having a wavelength of 810 nm. The optical signal output from the electrical / optical converter 405 and the optical signal output from the electrical / optical converter 406 are multiplexed by the optical multiplexer 407 and output to the optical fiber 408. The optical signal transmitted by the optical fiber 408 is transmitted by the optical demultiplexer 409 to the wavelength 1300 nm component and the wavelength 8
The signals are demultiplexed into optical signals of 10 nm component and output to the optical / electrical converter 410 and the optical / electrical converter 411, respectively. light/
The electric converters 410 and 411 convert the input optical signals into electric signals. Optical / electrical converter 410,
The electric signal output from 411 is amplified to the electric logic level by the AC coupling amplifiers 412 and 413, respectively. The timing extraction circuits 414 and 415 extract the transmission clock components from the output signals of the AC coupling amplifiers 412 and 413, respectively, and discriminate between "H" and "L" of the electrical logic level at the timing of this clock. The output signals of the timing extraction circuits 414, 415 are demodulated by delta sigma modulation by the delta demodulators 416, 417, respectively, and output to the analog audio signal output terminals 418, 419.

As described above, according to this embodiment, the number of quantization bits can be increased by using the delta modulators 403 and 404 and the delta demodulators 416 and 417 having a simple circuit structure even for audio signals of a plurality of channels. The need for large analog / digital converters and digital / analog converters has been eliminated. In addition, by delta-modulating the audio signal having no DC component, the mark rate is almost 50% at the time of the 1-bit delta-modulated signal, and the mark rate is 50%.
Therefore, an encoding circuit and a decoding circuit for achieving the above are unnecessary, and the circuit scale can be reduced.

Further, by using the 1-bit quantization delta modulation, direct serial transmission is possible, and the multiplexing / separation processing is not required. Therefore, the circuit scale becomes smaller, and the analog audio signal output terminal 41 is connected to the analog audio signal input terminals 401 and 402 after the audio signal is input.
It was possible to reduce the propagation delay time until output to 8,419.

Next, an audio signal transmission device (n = 8) according to the third embodiment of the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram showing the structure of an audio signal transmitting apparatus according to the third embodiment of the present invention. In FIG. 5, 501 is an analog audio signal input terminal group consisting of 8 channel terminals, 502 is a delta modulator group consisting of 8 delta modulators, 503 is a multiplex circuit, and 504 is electrical / electrical
An optical converter, 505 is an optical fiber, 506 is an optical / electrical converter, 507 is an AC coupling amplifier, 508 is a timing extraction circuit, 509 is a separation circuit, 510 is a delta demodulator group consisting of eight delta demodulators, and 511 is It is an analog audio signal output terminal group including terminals of 8 channels.

The operation of the audio signal transmission apparatus of this embodiment having the above-mentioned configuration will be described below.

The 8-channel analog audio signals input from the analog audio signal input terminal group 501 are delta-sigma modulated by the delta modulator group 502, and each is converted into a digital signal of 3 MHz sampling / quantization 1 bit. The 8-channel output signal of the delta modulator group 502 is added / multiplexed with frame bits by the multiplexing circuit 503 and converted into a serial signal having a frame structure as shown in FIG. 6A. The 1-bit electric signal output from the multiplexing circuit 503 is converted into an optical signal by the electric / optical converter 504 by light emission intensity modulation and output to the optical fiber 505. The optical signal transmitted by the optical fiber 505 is converted into an electric signal by the optical / electrical converter 506.
The electrical signal output from the optical / electrical converter 506 is amplified to an electrical logic level by the AC coupling amplifier 507. The timing extraction circuit 508 extracts the transmission clock component from the output signal of the AC coupling amplifier 507, and discriminates the electrical logic level between “H” and “L” at the timing of this clock. The serial signal output from the timing extraction circuit 508 is subjected to frame detection by the separation circuit 509 and separated into 8-channel signals. Separation circuit 508
The 8-channel signal output from the delta demodulator group 51
At 0, demodulation processing of delta sigma modulation is performed, respectively, and output to the analog audio signal output terminal group 511.

As described above, according to this embodiment, by using the delta modulator 502 and the delta demodulator 510 having a simple circuit configuration even for audio signals of a plurality of channels,
The analog / digital converter and digital / analog converter with a large number of quantization bits are no longer required. Further, by delta-modulating an audio signal having no DC component, the mark rate becomes almost 50% at the time of a 1-bit delta-modulated signal, and an encoding circuit and a decoding circuit for making the mark rate 50%. The circuit was not required, and the circuit scale could be reduced.

Furthermore, by using a high sampling frequency and delta modulation of 1-bit quantization, signal multiplexing and demultiplexing can be processed in a short time, and the analog audio signal input terminal group 501 can be used after analog signals have been input. The propagation delay time until output to the audio signal output terminal group 511 could be reduced.

Generally, when performing digital signal processing such as multiplexing / demultiplexing and digital filtering, the processing time is shorter and the propagation delay time is shorter when the sampling frequency of the data to be handled is higher. For example, when parallel audio signals of 48 kHz sampling / quantization 16 bits are multiplexed into 8 channels and framed, 128 bits (= 16 bits x
Information of 8 channels is 20.8 μs (= 1/48 kH)
z) must be remembered and held for 20.8
A delay time of μs occurs. On the other hand, in the present embodiment, since the audio signal of 3 MHz sampling / quantization 1 bit is multiplexed on 8 channels, 8 bits (1 bit × 1 bit ×
Information of 8 channels is 0.33 μs (= 1/3 MH)
Memory retention of the time of z) is sufficient, and the delay time becomes small.

Here, the mark ratio of the delta modulation signal will be described in more detail. It has been described above that the mark rate is almost 50% at the time of the 1-bit delta modulation signal by delta-modulating the audio signal having no DC component, but in reality, the mark rate is rarely 50%. In the delta sigma modulator of FIG. 2, if the D flip-flop 204 is composed of a CMOS transistor and operates at a power supply voltage of + 5V, the threshold level of the D input terminal of the D flip-flop 204 is 2 .
At 5 V, the mark ratio is 50% in an ideal state where the P-channel and N-channel on-resistances of the inverting output transistors are the same. However, in reality, the threshold level of the D input terminal is less than 2.5 V, and the ON resistances of the P channel and N channel of the inverting output transistor are often different, so the mark ratio of the delta-sigma modulated signal is 50%. It will fall off.

Therefore, in the audio signal transmission device of the present invention,
The object is to stably operate the AC coupling signal processing even if the mark ratio of the delta modulation signal deviates from 50%.

An audio signal transmission device (m = 4) according to the fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 7 is a block diagram showing the structure of an audio signal transmitting apparatus according to the fourth embodiment of the present invention. In FIG. 7, 701 is an analog audio signal input terminal group including terminals for 8 channels, 702 is a first delta modulator group including four delta modulators, and 703 is a second delta modulation including four delta modulators. Group, 704 is a first inverter group consisting of four inverters, 705 is a multiplex circuit,
706 is an electric / optical converter, 707 is an optical fiber, 708
Is an optical / electrical converter, 709 is an AC coupling amplifier, 710 is a timing extraction circuit, 711 is a separation circuit, 712 is a second inverter group consisting of four inverters, and 713 is 4
A first delta demodulator group consisting of two delta demodulators, 71
Reference numeral 4 is a second delta demodulator group including four delta demodulators, and 715 is an analog audio signal output terminal group including eight channel terminals.

The operation of the audio signal transmitting apparatus of this embodiment constructed as above will be described below.

The 8-channel analog audio signals input from the analog audio signal input terminal group 701 are respectively delta-sigma modulated by the first delta modulator group 702 and the second delta modulator group 703, and each sampled at 3 MHz. It is converted into a quantized 1-bit digital signal. The 4-channel digital signal output from the second delta modulator group 703 is output to the first inverter group 704.
Logic is inverted by each. A 4-bit output signal of the first inverter group 704 and a 4-channel output signal of the first delta modulator group 702 are frame-bit added / multiplexed by a multiplexing circuit 705.
It is converted into a serial signal having a frame structure as shown in (b). The 1-bit electric signal output from the multiplexing circuit 705 is converted into an optical signal by the electric / optical converter 706 by light emission intensity modulation and output to the optical fiber 707. The optical signal transmitted by the optical fiber 707 is converted into an electric signal by the optical / electrical converter 708. Optical / electrical converter 70
The electrical signal which is the output of 8 is amplified to an electrical logic level by the AC coupling amplifier 709. Timing extraction circuit 71
At 0, the transmission clock component is extracted from the output signal of the AC coupling amplifier 709, and the electrical logic level "H" or "L" is identified at the timing of this clock. The serial signal output from the timing extraction circuit 710 is subjected to frame detection by the separation circuit 711 and separated into 8-channel signals. Of the 8-channel signals output from the separation circuit 711, 4-channel signals corresponding to the channels that have passed through the first inverter group 704 are logically inverted by the second inverter group 712. Separation circuit 711
The remaining four channels of the signals of (1) are demodulated by delta sigma modulation in the first delta demodulator group 713 and output to the analog audio signal output terminal group 715. The 4-channel output signals of the second inverter group 712 are also demodulated by delta sigma modulation in the second delta demodulator group 714 and output to the analog audio signal output terminal group 715.

As described above, according to this embodiment, for example,
Even if the mark ratios of the respective delta modulator outputs in the first delta modulator group 702 and the second delta modulator group 703 are 48%, half of the delta modulator signals are logically processed by the inverter group 704. Since it is inverted, the mark rate of the signal after being multiplexed is 50%.

Further, by using a delta modulator or a delta demodulator having a simple circuit configuration for audio signals of a plurality of channels, an analog / digital converter or a digital / analog converter having a large number of quantization bits becomes unnecessary. The encoding circuit and the decoding circuit for making the mark rate 50% are unnecessary, and the circuit scale can be reduced.

Furthermore, by using the high sampling frequency and the delta modulation of 1-bit quantization, the multiplexing and demultiplexing of signals can be processed in a short time, and the analog audio signal input terminal group 701 receives an analog audio signal after the analog audio signal is input. The propagation delay time until output to the audio signal output terminal group 715 could be reduced.

[0050]

As described above, according to the present invention, the circuit scale can be reduced and the propagation delay time can be shortened by providing the delta modulator, the AC coupling amplifier and the delta demodulator. it can. Moreover, its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an audio signal transmission device according to a first embodiment (claim 1) of the present invention.

FIG. 2 is a circuit diagram showing an example of a single integral delta sigma modulator according to the embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a delta-sigma demodulator according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an audio signal transmission device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an audio signal transmission device according to a third embodiment of the present invention.

FIG. 6A is a schematic diagram showing a transmission frame configuration of an audio signal transmission device according to a third embodiment of the present invention. (B) A schematic diagram showing a transmission frame configuration of an audio signal transmission device according to a fourth embodiment of the present invention. Figure

FIG. 7 is a block diagram showing a configuration of an audio signal transmission device according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of an audio signal transmission device in a conventional example.

[Explanation of symbols]

102, 403, 404 Delta modulator 103, 405, 406, 504, 706 Electric / optical converter 104, 408, 505, 707 Optical fiber 105, 410, 411, 506, 708 Optical / electrical converter 106, 412, 413 , 507, 709 AC coupling amplifier 107, 414, 415, 508, 710 Timing extraction circuit 108, 416, 417 Delta demodulator 407 Optical multiplexer 409 Optical demultiplexer 502 Delta modulator group 503, 705 Multiplexing circuit 509, 711 Separation Circuit 510 Delta demodulator group 702 First delta modulator group 703 Second delta modulator group 704 First inverter group 712 Second inverter group 713 First delta demodulator group 714 Second delta demodulator group

Claims (4)

[Claims] 1. A delta modulator that delta-modulates an analog audio signal and outputs a 1-bit digital signal; an electro-optical converter that converts an electric signal output from the delta modulator into an optical signal; An optical fiber that transmits an optical signal that is the output of the electrical / optical converter, an optical / electrical converter that converts the optical signal transmitted by the optical fiber into an electrical signal, and an output of the optical / electrical converter that is electrically coupled. Coupling amplifier for amplifying to a logical level, a timing extraction circuit for extracting a clock and data discrimination from the output of the AC coupling amplifier, a 1-bit signal output from the timing extraction circuit for demodulating delta modulation, and an analog signal. An audio signal transmission device including a delta demodulator that outputs an audio signal. 2. A k-number (k is an integer of 2 or more) delta modulator that delta-modulates an analog audio signal and outputs a 1-bit digital signal, and output electric signals of each of the k delta modulators. Of k electric / optical converters for converting optical signals of different wavelengths, an optical multiplexer for multiplexing optical signals output from the k electric / optical converters, and An optical fiber that transmits an optical signal that is an output, an optical demultiplexer that demultiplexes the optical signal transmitted by the optical fiber into k types of optical signals according to an optical wavelength, and k types of light of the optical demultiplexer K optical / electrical converters for converting each signal into an electric signal, k AC coupling amplifiers for amplifying the outputs of the k optical / electrical converters to electric logic levels, and the k Clock extraction from each output of AC coupling amplifier There are k timing extraction circuits that perform data identification, and k delta demodulators that perform delta modulation demodulation from each of the 1-bit signals output from the k timing extraction circuits and output an analog audio signal. The configured audio signal transmission device. 3. A delta modulator group consisting of n delta modulators which respectively delta-modulates analog audio signals of n channels (n is an integer of 2 or more) and outputs a 1-bit digital signal, and the delta modulation. Circuit that multiplexes the output signals of the device group and outputs a 1-bit serial electric signal, an electric / optical converter that converts the electric signal that is the output of the multiplexing circuit into an optical signal, and the electric / optical converter An optical fiber that transmits an optical signal that is an output of the optical fiber, an optical / electrical converter that converts the optical signal transmitted by the optical fiber into an electrical signal, and an output of the optical / electrical converter is amplified to an electrical logic level. An AC coupling amplifier, a timing extraction circuit that performs clock extraction and data identification from the output of the AC coupling amplifier, and an n-channel signal from the 1-bit signal output from the timing extraction circuit. And a delta demodulator group consisting of n delta demodulators for outputting analog audio signals by performing delta modulation demodulation from each signal output from the separation circuit. Audio signal transmission equipment. 4. A first delta modulator group consisting of m delta modulators for delta-modulating analog audio signals of m channels (m is an integer of 1 or more) and outputting a 1-bit digital electric signal. A second delta modulator group consisting of m delta modulators for respectively delta-modulating m channel analog audio signals different from the first delta modulator group and outputting a 1-bit digital electric signal. A first inverter group consisting of m inverters that inverts the logic of each of the output signals of the second delta modulator group; and an output signal of the first inverter group and a first delta modulator group. A multiplexing circuit that multiplexes the output signals and outputs a 1-bit serial electrical signal; an electrical / optical converter that converts the electrical signal output from the multiplexing circuit into an optical signal; An optical fiber for transmitting an optical signal which is an output of the converter, an optical / electrical converter for converting the optical signal transmitted by the optical fiber into an electric signal, and an output of the optical / electrical converter at an electrical logic level An AC coupling amplifier that amplifies to, a timing extraction circuit that performs clock extraction and data identification from the output of the AC coupling amplifier, a separation circuit that separates a 1-bit signal output from the timing extraction circuit into a 2m channel signal, A second inverter group composed of m inverters each logically inverting a signal of m channels corresponding to a channel whose logic is inverted in the output signal of the separation circuit, and an output of the second inverter group. First delta demodulator group consisting of n delta demodulators for demodulating a signal by delta modulation and outputting an analog audio signal Demodulates the delta modulation from each of the non-inverted signal of the output of the separation circuit, and a second delta demodulator group of n delta demodulator for outputting an analog audio signal,
An audio signal transmission device composed of.