JPS6218842A - Optical communication transmission equipment - Google Patents

Abstract

PURPOSE:To easily perform electric conversion and to perform carry out transmission simultaneously by providing an optical switch which intermits the output light of a light emitting element with a digital signal which has a higher frequency than an electric signal and contains a small number of succeeding '0's. CONSTITUTION:An analog signal input is converted into an analog light signal, which is outputted by the light emitting element. This output light is supplied to the optical switch 3. Further, a digital signal input is supplied as a on-off signal to the optical switch 3 through a driving circuit 4. A receiver shown in a figure is usable so as to regenerate a light signal on a reception side. A light receive signal is converted into an electric signal by an optoelectric converting element 5, e.g. APD. This conversion output is amplified by an automatic gain adjusting amplifier 6. Its signal is discriminated by a comparator 7 having a discrimination level Vth and led out as a digital signal. Part of the output of the amplifier 6 is detected by a peak detector 8 and led out as an analog signal through a low-pass filter 9.

Description

[Detailed Description of the Invention] [Summary] An optical communication transmission device that performs electro-optical conversion, an optical switch that can switch a low-speed optical signal with a relatively high-speed digital electrical signal.

By intermittent.

This allows two types of electrical signals to be transmitted simultaneously as optical signals through one transmission line.

[Industrial application field]

The present invention relates to improvements in optical communication transmitting devices used in optical communication systems.

An optical communication transmitting device converts an electrical signal into an optical signal using an electro-optic converter, and sends it to a transmission line as a strong/weak light or an intermittent optical signal.

Optical communication systems can simultaneously transmit a large amount of signals through one transmission path, but it is desirable to be able to transmit the above-mentioned strong and weak optical signals and intermittent optical signals at the same time, as this would further enable multiplexing.

[Conventional technology]

In optical communication systems, digital signals and analog signals are distinguished from each other, and a system in which they are transmitted simultaneously is not used.

Furthermore, when optically transmitting two types of signals, such as a high-speed data signal and a low-speed order wire signal, these two types of electrical signals are superimposed in advance, and then this superimposed signal is used to drive a high-speed light emitting device such as a laser diode. A driving method is conventionally used. However, in this case, a complicated drive circuit is required due to the characteristics of the light emitting element.

[Problem that the invention seeks to solve]

An object of the present invention is to enable simultaneous transmission of digital signals and analog signals, and to easily implement the method without complicating the light emitting element driving circuit when transmitting two types of signals such as high-speed data signals and low-speed order wire signals at the same time. An object of the present invention is to provide an optical communication transmitting device.

[Means for solving problems]

The above problem is that the light emitting element (2) is intensity-modulated by an electric signal, and the output light of the light emitting element (2) is intermittent by a digital signal that has a higher frequency than the electric signal and has less O continuity. The problem is solved by an optical communication transmitting device according to the invention, which comprises a switch (3).

[Effect]

According to the invention, the light output of the light emitting device is amplitude modulated by a low speed signal such as an analog signal or an order wire signal. This modulation result is supplied to the optical switch, connected to IIrfr by a high-speed digital signal, and outputted from the optical switch as a pulse amplitude modulated optical signal. This optical output signal simultaneously transmits the original low speed signal and high speed digital signal components.

According to the present invention, the number G such as PLZT thin film switch
Uses an optical switch element with high-speed response of Hz or higher.

It is possible to combine light emitting elements with an uncomplicated drive circuit.

〔Example〕

The present invention will be described in detail according to the illustrated embodiments.

Fig. 1 is a block circuit diagram showing an embodiment of the optical communication transmitter, Fig. 2 is an operating waveform diagram of the optical communication transmitter shown in Fig. 1, and Fig. 3 is a block circuit diagram showing an example of the optical communication transmitter shown in Fig. 1. A block circuit diagram showing an embodiment of the optical communication receiving device; FIG. 4 is an operational waveform diagram of the optical communication transmitting device shown in FIG. 3;

FIG. 5 is a block circuit diagram showing another embodiment of the optical communication transmitting device, and FIG. 6 is an optical output waveform diagram from the optical communication transmitting device of FIG.

FIG. 7 is a circuit diagram showing an embodiment of the optical communication receiving device for receiving the optical signal shown in FIG. 6, and FIG. 8 is an operational waveform diagram of the optical communication transmitting device shown in FIG. 7.

In FIG. 1, an analog signal drives a light emitting element, for example, an LED 2, via a drive circuit 1, and the analog signal is converted into an optical signal.

FIG. 2 shows optical output on the vertical axis and time on the horizontal axis.

The analog signal input is converted into an analog optical signal and output from the light emitting element 2, as shown in FIG.

This output light is supplied to the optical switch 3.

Further, the digital signal input is supplied to the optical switch 3 via the drive circuit 4 as an on/off signal shown in FIG.

The optical switch 3 intermittents the optical signal (2) and outputs the optical signal shown in (2) in FIG.

On the receiving side, the receiving device of FIG. 3 can be used to regenerate the optical signal.

The optical reception signal is converted into an electrical signal by a photoelectric conversion element 5, for example, an APD. This converted output is amplified by the automatic gain adjustment amplifier 6 and becomes a waveform shown in FIG. In FIG. 4, the vertical axis represents voltage and the horizontal axis represents time.

This signal is identified by a comparator 7 having an identification level VLh as shown in FIG.

A part of the output of the amplifier 6 is detected by a peak detector 8 and taken out through a low-pass filter 9 as an analog signal with the waveform shown in FIG.

Note that the output of the peak detector 8 is automatically controlled by the control circuit 10.
The automatic gain adjustment amplifier 6 is controlled via the .

When implementing the present invention, if the digital signal is a long signal with continuous O's, the period during which the optical switch 3 is open will be long and there is a possibility that changes in the analog signal cannot be faithfully transmitted. It is recommended to use a digital signal with few consecutive 0's or suppressed consecutive O's, such as a CMr code or a Manchester code, converted into IB2BB2.

In addition, a certain relationship is established between the maximum frequency fmax of the analog signal and the bit rate fb (bits/second) of the digital signal, and in the case of the digital signal of the above IB2B code, the bit rate of the original digital signal is fb, fmax ≦ fb/6.

Next, an embodiment for transmitting high-speed data signals and low-speed order wire signals will be described with reference to FIGS. 5 to 8.

In FIG. 5, an order wire signal is supplied to the input of the drive circuit 1', and a high speed data signal is supplied to the input of the drive circuit 4.

FIG. 6 shows the optical output from the optical switch 3, and in FIG. 1, ■ indicates an order wire signal, and ■ indicates a high-speed data signal component.

FIG. 7 is a block circuit diagram of an optical communication receiver for transmitting high-speed data signals and low-speed order wire signals.

The output of the automatic gain adjustment amplifier 6 has a waveform shown in FIG. This is identified by the discrimination level Vthl in the comparator 71, and is output from the output section of the comparator 71 as a data signal. In addition, the order wire signal is obtained through the peak detector 8 and the signal of [phase] in FIG.
The comparator 72
is output as an order wire signal to the output section of.

〔Effect of the invention〕

The present invention allows low-speed signals and high-speed digital signals to be easily subjected to electro-optical conversion using the same transmitting device and transmitted simultaneously, and its effects are extremely large.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram showing an embodiment of the optical communication transmitter, Fig. 2 is an operational waveform diagram of the optical communication transmitter shown in Fig. 1, and Fig. 3 is a block diagram showing an embodiment of the optical communication receiver. Circuit diagram: FIG. 4 is an operating waveform diagram of the optical communication receiver shown in FIG. FIG. 5 is a block circuit diagram showing another embodiment of the optical communication transmitting device, and FIG. 6 is an optical signal output waveform diagram from the optical communication transmitting device of FIG. FIG. 7 is a block circuit diagram of an optical communication receiver for transmitting high-speed data signals and low-speed order wire signals. FIG. 8 is an operational waveform diagram of the optical communication receiver shown in FIG. 7. In the figure, 1.1', 4 is a drive circuit, 2 is a light emitting element, 3 is an optical switch, 5 is a photoelectric conversion element, 6 is an automatic gain adjustment amplifier, ? , 71 and 72 are discriminators, 8 is a peak detector, 9 is a low-pass filter, and 10 is an automatic gain control circuit. I2E 1072 circuit exit of Hunger and Song's Helmet A series 1
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Claims (1)

[Claims] A light emitting element (2) whose intensity is modulated by an electric signal, and an optical switch (3) which intermittents the output light of the light emitting element (2) using a digital signal that has a higher frequency than the electric signal and has fewer consecutive zeros. An optical communication transmitting device characterized by: