JPH0226145A - Optical signal switching device - Google Patents

Abstract

PURPOSE:To execute switching without the degradation of signal quality by converting an optical signal, for which luminance modulation is executed with a pulse FM signal to include a control signal, to an electric signal, after that, changing-over a switch with the control signal and executing connection to an optical transmission part. CONSTITUTION:An optical signal 17 is converted to an electric signal 25 by an optical receiving part 18 and impressed to a signal switching part 19. For the signal 25, a digital switching can be used as the switching part 19 by the pulse FM signal, for which a picture, a sound and the control signal are multiplexed. An electric signal 26 to branch the signal 25 is demodulated to the pulse FM signal by a signal demodulating part 20 and after that, only a control signal 27 is fetched by a frequency filter, regenerated and impressed to a switch control part 21. In correspondence to the contents of the signal 27, the signal is switched and connected to any one of optical transmission parts 22-24. In the optical transmission parts 22-24, the luminance modulation is directly executed for the output light of an LED, etc., and the output light is sent to a transmission path as an optical signal 29.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical signal switching device used for switching and transmitting optical signals to a plurality of optical transmission lines.

(Prior Art) In optical communication networks and the like, it is necessary to transmit optical signals by switching and selecting transmission paths.

Figure 3 shows the configuration of a conventional optical signal switching device used in such cases, where 1 is an optical receiver that converts the received optical signal into an electrical signal, and 2 is a signal separator that performs frequency multiplexing. The electrical signal sent is separated into each frequency component. 3
and 4 are signal changeover switches controlled by the switch control unit 5, and the respective output signals are selectively applied to the signal multiplexing units 6 to 8, frequency multiplexed, and optically transmitted by the optical transmitting units 9 to 11. It is converted into a signal and sent to an optical transmission line.

In such a configuration, the optical signal 12 applied to the optical receiver 1 is frequency-multiplexed into three signals: a video signal, an audio signal, and a control signal, and the multiplexed signal generates, for example, L
This is an optical signal obtained by direct brightness modulation (baseband modulation method) of the output of a light source such as an ED (light emitting diode), and the optical receiver 1 converts it into an electrical signal, and the signal separator 2 converts it into the above three signals.

Video signal 13. The video signal 13 and the audio signal 14 are separated into an audio signal 14 and a control signal 15, and the video signal 13 and the audio signal 14 are applied to the signal changeover switches 3 and 4, respectively, and the video signal 13 is controlled by the switch control section 5, which is controlled by the input of the control signal 15. , the audio signal 14 is input to the next stage, for example, the signal multiplexing section 6. Here, the video signal 13 and the audio signal 14 are again frequency-multiplexed and sent from the optical transmitter 9 to the optical transmission route as an optical transmission signal 16.

Conventionally, an optical reception signal has been switched to an arbitrary optical transmission route and sent out in one or more ways.

(Problems to be Solved by the Invention) However, in the conventional configuration described above, since the signal is baseband modulated and transmitted, an expensive analog signal switch is required as the signal changeover switch.

In addition, in order to minimize the quality deterioration of signals that have passed through such switches, after separating a single frequency multiplexed signal into a video signal and an audio signal, a matched switch is provided for each signal and the signals are multiplexed again. Therefore, the structure is complicated and expensive.

In view of the above, it is an object of the present invention to provide an optical signal switching device that switches and inputs a received signal to an arbitrary optical transmitter using a simple circuit configuration without causing signal quality deterioration.

(Means for Solving the Problems) The present invention aims to provide an optical receiver that receives an optical signal brightness-modulated by a pulsed FM signal including a control signal and converts it into an electrical signal, and an optical receiver for the optical receiver. A signal switching section consisting of a single switch that switches and inputs the electrical signal output of the above to any one of the plurality of optical transmitting sections, and a signal demodulating section that extracts only the control signal from the above electrical signal, and the above-mentioned control Controlling the switching operation of the signal switching section according to the signal,
This is achieved by selectively inputting the electrical signal to any one of a plurality of optical transmitters.

(Function) According to the present invention configured as described above, the signal received by the optical receiver can be directly applied to the changeover switch using a pulsed FM signal, and furthermore, the signal can be directly inputted to any optical transmitter. It operates as an optical signal switch with a simple configuration and excellent signal quality.

(implementation@) Hereinafter, the present invention will be explained with reference to examples and drawings.

FIG. 1 is a block diagram showing an optical signal switching device according to an embodiment of the present invention. Reference numeral 17 denotes an input optical signal, which is applied to an optical receiver 18 and converted into an electrical signal. 19 is an optical receiving section 18
20 is a signal demodulation section that pulses and demodulates the electrical signal output from the optical receiver 18 and extracts only a control signal; 21 is a switch that controls switching of the signal switching section 19; The control sections 22 to 24 are optical transmitting sections corresponding to the transmission direction of the output of the signal switching section 19.

The optical signal 17 is an optical signal obtained by modulating a signal obtained by frequency multiplexing a video signal, an audio signal, and a control signal into a pulsed FM signal, and modulating the brightness of the output of a light source such as an LED using the pulsed FM signal. , the waveform of the pulsed FM signal is shown in FIG.

The analog signal a of the transmission signal is frequency modulated (FM) and F
Obtain the M wave, slice the top and bottom of its amplitude and make it into a pulse F
It is created as M signal C. This pulsed FM signal C carries the information of the original transmission signal in the pulse time axis direction, so
Compared to the baseband method shown in the conventional example, digital signal processing is possible.

In contrast to FIG. 1, such an optical signal 17 is transmitted to the optical receiver 1.
After being converted into an electric signal 25 by 8, the signal switching unit 19
is applied to Here, since the electrical signal 25 is a pulsed FM signal that is a multiplexed video signal, audio signal, and control signal, it is advantageous that a digital signal switch can be used as the changeover switch constituting the signal switching section 19.

The electrical signal 26 branched from the electrical signal 25 is sent to the signal demodulator 2.
After being demodulated into a pulsed FM signal, only the control signal 27 is extracted using a one-frequency filter, regenerated, and applied to the switching control section 21. The switching control section 21 controls the signal switching section 19 according to the contents of the applied control signal 27, and switches and connects the electrical signal 25 to an arbitrary optical transmitting section, for example, the optical transmitting section 22. The input signal 28 is the electrical signal 2
This is a pulsed FM signal obtained by frequency multiplexing the same video signal, audio signal, and control signal as in No. 5. The optical transmitter 22 directly modulates the brightness of output light from an LED or the like using the input signal 28 and sends it out as an optical signal 29 to a transmission line.

The present invention has been described above with reference to one embodiment, and its characteristics are as follows:
The signal received by the optical receiving section 18 is directly input to an arbitrary optical transmitting section via the signal switching section 19 consisting of a single changeover switch, so that signal switching can be performed while maintaining high signal quality. As the signal switching unit 19 using the single changeover switch, a digital signal switch with a simple configuration can be used.

Further, the signal demodulating section 20 is simple in demodulating and reproducing only the control signal.

In the above embodiment, the signal demodulation section 20 demodulated the pulsed FM signal and then used the frequency filter to obtain the control signal, but the order may be reversed, and the signal to be sent may be the same as the video signal. The explanation was given by frequency multiplexing the three signals, the audio signal and the control signal.

Of course, there is no limit to the number of signals to be multiplexed or the multiplexing method.

(Effects of the Invention) As is clear from the detailed explanation above, the optical signal switching device of the present invention uses a digital signal switch and directly connects the output signal of the optical receiver through a single signal switching section. Since the optical transmitter is connected to the optical transmitter, it has the effect of enabling excellent signal switching with almost no deterioration in signal quality with an extremely simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an optical signal switching device according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram that is an auxiliary diagram for explaining FIG. 1, and FIG. 3 is a diagram showing the configuration of a conventional signal switching device. It is a block diagram. 1... Optical receiver, 2... Signal separation unit. 3.4...Signal changeover switch, 5...Switch control section, 6,7.8...Signal multiplexing section, 9,10.1
DESCRIPTION OF SYMBOLS 1... Optical transmitting part, 17... Optical signal, 18... Optical receiving part, 19... Signal switching part, 20... Signal demodulating part, 21... Switching control part, 22.23 .24... Optical transmitter. Figure 1 Figure 2 □Sakikai

Claims (1)

[Claims] An optical receiver that receives an optical signal brightness-modulated by a pulsed FM signal including a control signal and converts it into an electrical signal, and switches the electrical signal output of the optical receiver to any one of a plurality of optical transmitters. It is composed of a signal switching section consisting of a single switch, and a signal demodulation section that extracts only the control signal from the electrical signal.The switching operation of the signal switching section is controlled by the control signal, and the electrical An optical signal switch that selectively inputs a signal to any one of a plurality of optical transmitters.