JPH06104833A - Signal transmission system - Google Patents

Abstract

PURPOSE:To provide the signal transmission system to send an analog signal through an optical fiber. CONSTITUTION:A sender side is provided with a modulation means 1, which converts an input analog signal into a signal comprising a pulse train, with an electrooptic conversion means 2 to convert the signal comprising the pulse train into an optical signal and the optical signal is sent through an optical fiber 3. A receiver side is provided with an optoelectric conversion means 4, which converts the received optical signal into an electric signal, with a demodulation means 5 converting the pulse train of the electric signal into the original analog signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission system, and more particularly to a signal transmission system for transmitting an analog signal using an optical fiber.

In the field of signal transmission, an analog signal such as voice or video is transmitted through a transmission path, and the receiving side restores the original information such as voice or video, thereby transmitting the signal. Try to achieve the purpose.

As one form of such signal transmission,
There is a need to be able to transmit analog signals over optical fibers.

[0004]

2. Description of the Related Art Conventionally, when an electric signal consisting of an analog signal is transmitted through an optical fiber, the analog signal is directly converted into an optical signal by using an electric / optical (E / O) converter using a laser diode. A method of converting a signal and transmitting it through an optical fiber is generally used.

[0005]

In the conventional signal transmission system as described above, conversion is performed based on the non-linear characteristic of the laser diode used in the E / O conversion unit for converting an electric signal into an optical signal. There is a limit to the dynamic range of possible analog signals.

Therefore, when the level of the input signal is large and exceeds the range of the linear characteristic of the laser diode, adaptive control is performed on the input level in order to keep it within the required range. Was necessary.

The present invention is intended to solve such a problem of the prior art, and in a signal transmission system for transmitting an analog signal using an optical fiber, a prescribed dynamic range is obtained at the time of E / O conversion. An object of the present invention is to provide a signal transmission system that does not require an operation such as adaptively controlling the level of an input analog signal in order to make it fit.

[0008]

[Means for Solving the Problems]

(1) The present invention includes, on the transmission side, a modulation means 1 for converting an input analog signal into a signal consisting of a pulse train, and an electric / optical conversion means 2 for converting the signal of the pulse train into an optical signal. A signal is transmitted through the optical fiber 3, and an optical / electrical converting means 4 for converting the received optical signal into an electric signal and a demodulating means 5 for converting a pulse train of the electric signal into an analog signal are provided on the receiving side. It is a thing.

(2) Further, in the present invention according to (1), the Δ modulation section 11 for converting the analog signal into the Δ modulation signal by the modulation means 1
The demodulation means 5 comprises a Δ demodulation section 15 for converting the Δ modulated signal into an analog signal.

(3) Further, in the present invention according to (1), the modulation means 1 comprises a ΔΣ modulation section 16 which converts an analog signal into a ΔΣ modulation signal, and the demodulation means 5 converts the ΔΣ modulation signal into an analog signal. The demodulator 17 is included.

(4) Further, in the present invention, in any one of (1) to (3), a frequency converting means 6 for converting a high frequency signal into a lower frequency signal is provided, and the converted low frequency signal is supplied. The signal is converted into a signal composed of a pulse train.

[0012]

In the present invention, as shown in the principle configuration of FIG. 1, the analog signal input is Δ-modulated or ΔΣ-modulated on the transmitting side to be converted into a pulse series signal. Then, the pulse sequence is subjected to electrical / optical conversion, and the converted optical signal is transmitted through the optical fiber.

On the receiving side, the pulse train of light transmitted through the optical fiber is received and converted into a pulse train of electrical signals by performing optical / electrical conversion. In the case of a Δ modulated signal, this pulse train is time-converted. Is integrated, and in the case of a ΔΣ modulated signal, the original analog signal is reproduced by temporally integrating and differentiating this pulse train.

In the Δ modulation or ΔΣ modulation method, an input analog signal is converted into a pulse train type signal having a constant amplitude. That is, depending on the amplitude of the original analog signal,
The frequency of pulse generation is changed.

As described above, since the input analog signal is Δ-modulated or ΔΣ-modulated and converted into a pulse series signal, the form of the signal to be transmitted by the optical fiber is a pulse train having a constant amplitude. Therefore, the range of the signal input to the conversion unit that performs the electrical / optical conversion is a constant value determined from the amplitude of the input pulse, and does not change temporally (dynamically).

Therefore, according to the signal transmission system of the present invention,
There is no restriction on the dynamic range of the signal to be transmitted. Further, in order to fit within the specified dynamic range, the operation of adaptively controlling the level of the analog signal becomes unnecessary.

[0017]

FIG. 2 shows a first embodiment of the present invention. 11 is a delta modulator, 12 is electrical / optical conversion (E /
O) part, which constitutes the transmitting side. Thirteen
Is an optical fiber. 14 is optical / electrical conversion (O / E)
Reference numeral 15 denotes a Δ demodulation unit, which constitutes a receiving side.

On the transmitting side, the Δ modulator 11 generates a pulse series signal by subjecting an input analog signal, which is an electric signal, to Δ modulation. E / O section 12
Converts the pulse series signal from the Δ modulator 11 into an optical signal by performing electrical / optical conversion. The optical signal composed of the generated pulse sequence is sent to the receiving side via the optical fiber 13.

On the receiving side, the O / E section 14 performs optical / electrical conversion on the received optical signal to convert it into a pulse sequence consisting of an electric signal. Δ demodulator 15
Reproduces the original analog signal by temporally integrating the pulse series signal from the O / E unit 14.

Therefore, according to the embodiment shown in FIG. 2, an electric signal composed of an analog signal can be transmitted using an optical fiber. At this time, since the Δ modulated signal is converted into a pulse series signal and transmitted, there is no restriction on the dynamic range due to the non-linear characteristics of the electrical / optical conversion unit.

FIG. 3 shows a second embodiment of the present invention, in which the same components as those in FIG. 2 are designated by the same reference numerals, and 16 is a Δ for modulating an analog signal into a ΔΣ modulation signal.
The Σ modulation unit 17 is a ΔΣ demodulation unit that demodulates the ΔΣ modulation signal into an analog signal.

On the transmitting side, the ΔΣ modulation section 16 generates a pulse series signal by subjecting an input analog signal consisting of an electric signal to ΔΣ modulation. The E / O unit 12 converts the pulse-series signal from the ΔΣ modulation unit 16 into an optical signal by performing electrical / optical conversion. The optical signal composed of the generated pulse sequence is sent to the receiving side via the optical fiber 13.

On the receiving side, the O / E section 14 performs optical / electrical conversion on the received optical signal to convert it into a pulse sequence consisting of an electric signal. ΔΣ demodulation unit 17
Reproduces the original analog signal by temporally performing integration and differentiation operations on the pulse series signal from the O / E unit 14.

Therefore, according to the embodiment shown in FIG. 3, an electric signal composed of an analog signal can be transmitted using an optical fiber. At this time, as the ΔΣ modulated signal is converted into a pulse series signal and transmitted, there is no restriction on the dynamic range due to the non-linear characteristics of the electrical / optical conversion unit.

FIG. 4 shows a third embodiment of the present invention, in which the same components as those in FIG. 2 are designated by the same reference numerals, and 18 is a signal from a high frequency band to a signal in a lower frequency band. A frequency conversion unit for converting into
A modulator for performing Σ modulation, and a demodulator 20 for performing Δ demodulation or ΔΣ demodulation.

On the transmitting side, the frequency converter 18 performs frequency conversion on an analog signal having an information signal in a high frequency band such as a radio signal, and converts it into an analog signal in a lower frequency band. The modulator 19 includes the frequency converter 1
A pulse series signal is generated by subjecting the output signal of 8 to Δ modulation or ΔΣ modulation. E / O part 1
2 performs electrical / optical conversion on the pulse series signal from the modulator 19 to convert it into an optical signal. The optical signal composed of the generated pulse sequence is sent to the receiving side via the optical fiber 13.

On the receiving side, the O / E section 14 performs optical / electrical conversion on the received optical signal to convert it into a pulse sequence consisting of an electric signal. The demodulation unit 20
The pulse series signal from the O / E unit 14 is temporally integrated in the case of a Δ modulated wave, and temporally integrated and differentiated in the case of a ΔΣ modulated wave to obtain the original analog signal. Play the signal.

Therefore, according to the embodiment shown in FIG. 4, after converting an electric signal composed of an analog signal in a high frequency band into an analog electric signal in a lower frequency band, Δ modulation or ΔΣ modulation is performed, By converting it into a pulse series signal, it can be transmitted using an optical fiber.

[0029]

As described above, according to the present invention, since an analog signal is converted into a pulse series signal by Δ modulation or ΔΣ modulation and then converted into an optical signal, an analog electric signal is converted into an optical signal. An analog signal with a wide dynamic range can be transmitted using an optical fiber without being affected by the non-linear characteristics of the electro-optical conversion unit, and in order to keep the analog signal within the specified dynamic range, The operation of adaptively controlling the signal level becomes unnecessary. Further, at this time, even an analog signal in a high frequency band can be similarly transmitted by using an optical fiber by converting it into a signal in a lower frequency band.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

FIG. 2 is a diagram showing a first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Modulation means 2 Electric / optical conversion means 3 Optical fiber 4 Optical / electrical conversion means 5 Demodulation means 6 Frequency conversion means 11 Δ modulation section 15 Δ demodulation section 16 ΔΣ modulation section 17 ΔΣ demodulation section

Claims (4)

[Claims] 1. The transmitting side is provided with a modulation means (1) for converting an input analog signal into a signal consisting of a pulse train, and an electrical / optical conversion means (2) for converting the signal of the pulse train into an optical signal, Transmitting the optical signal through an optical fiber (3),
An optical signal for converting the received optical signal to an electric signal on the receiving side
A signal transmission system characterized in that an electric converting means (4) and a demodulating means (5) for converting a pulse train of the electric signal into an analog signal are provided. 2. The modulation means (1) outputs an analog signal Δ
2. The Δ modulation section (11) for converting into a modulation signal, and the demodulation means (5) comprises a Δ demodulation section (15) for converting the Δ modulation signal into an analog signal. Signal transmission method. 3. The modulation means (1) outputs an analog signal Δ
The ΔΣ modulation section (16) for converting into a Σ modulation signal, and the demodulation means (5) comprises a ΔΣ demodulation section (17) for converting the ΔΣ modulation signal into an analog signal. Signal transmission method. 4. The signal transmission system according to claim 1, further comprising a frequency conversion means (6) for converting a high frequency signal into a lower frequency signal, the converted low frequency signal A signal transmission method, wherein a signal of a frequency is converted into a signal composed of the pulse train.