JPH0371737A - Remote monitor optical transmitter - Google Patents

Abstract

PURPOSE:To facilitate the installation of a transmission line by modulating an image pickup signal of monitor cameras at plural positions at a different frequency respectively, synthesizing them and sending the result through an optical fiber, demultiplexing the optical signal sent with an optical receiver and monitoring separately each image pickup signal. CONSTITUTION:An image pickup signal of monitor cameras 1A, 1B is subjected to PFM modulation at a different frequency at optical transmitters 2A, 2B respectively. Thus, even when the signals are synthesized in an optical fiber 5, it is possible to separate at a band pass filter 8 of the optical receiver 6 as a separate video image for the monitoring. Thus, one optical fiber 5 connecting the optical synthesizer 4 arranged to a monitor camera and the optical receiver 6 in a central monitor room is enough and even when the distance between the monitor location and the central monitor room is long, the transmission line is easily installed and inexpensively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a remote monitoring device, and more particularly to a remote monitoring optical transmission device that connects a monitoring point and a central monitoring room with an optical fiber.

[Conventional technology]

Conventionally, this type of long-distance monitoring optical transmission device modulates an image signal captured by a surveillance camera using a pulsed FM (PFM) method, transmits this modulated optical signal through an optical fiber, and transmits the video signal in a central monitoring room. It is configured to demodulate and monitor. In this case, PFM modulation is performed at the same modulation frequency at each of the plurality of monitoring locations.

[Problem to be solved by the invention]

In the above-mentioned conventional long-distance monitoring optical transmission device, transmission paths are constructed by separately extending optical fibers between the plurality of monitoring points and the central monitoring room so that the respective optical signals are not mixed. For this reason, although it is advantageous in that optical transmitters of the same standard can be used for the optical transmitters installed at each monitoring location, individual transmission paths are required, which increases the number of optical fibers, especially for monitoring. If the distance between the central monitoring room and the central monitoring room is long, there are problems in that the installation work is difficult and the equipment costs are high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a remote monitoring optical transmission device that makes it possible to reduce the number of optical fibers.

[Means to solve the problem]

The remote monitoring optical transmission device of the present invention includes monitoring cameras arranged at multiple locations, a plurality of optical transmitters that modulate and output imaging signals from these monitoring cameras at different frequencies, and an output from each optical transmitter. a multiplexer that combines the optical signals transmitted through the multiplexer, an optical fiber connected to the multiplexer and extended to a central monitoring room, and a multiplexer that combines the optical signals transmitted through the optical fiber for each of the frequencies. It consists of a demultiplexing means for demultiplexing, a plurality of demodulators for demodulating each demultiplexed optical signal, and a monitor for displaying each demodulated signal as an image.

[Effect]

In this configuration, the imaging signals from surveillance cameras at multiple locations are modulated at different frequencies, multiplexed, and transmitted through an optical fiber, and the optical receiver demultiplexes this transmitted optical signal and separates it into each imaging signal. By doing so, it becomes possible to transmit a plurality of imaging signals using one optical fiber.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. In the figure, IA and IB are surveillance cameras installed at different locations, and although these cameras are located away from the central monitoring room, surveillance cameras IA and IB
It is assumed that they are placed relatively close to each other.

The surveillance camera IA is connected to an optical transmitter 2A, where the image signal taken by the surveillance camera IA is transmitted to the PF at a frequency Fl.
It is output to the optical fiber 3A as an M-modulated optical signal. Similarly, surveillance camera IB is connected to optical transmitter 2B,
It is output to the optical fiber 3B as an optical signal PFM modulated at frequency FZ (Fl≠FZ). And each optical fiber 3A.

The 3B signals are combined in an optical multiplexer 4 and output to one optical fiber 5.

This optical fiber 5 is extended to a central monitoring room, and the optical signal transmitted through the optical fiber 5 is detected by a photodetector 7 of an optical receiver 6 provided in the central monitoring room. The signal is then split into frequencies Ft and F2 by the bandpass filter 8, and the signal at the frequency Fl is demodulated as a video signal by the demodulator 9A, and displayed as a video signal on the monitor 10B. Similarly,
The signal of frequency F2 is demodulated by demodulator 9B and displayed as an image on monitor 10B.

Therefore, in this device, each surveillance camera IA.

Since the IB imaging signals are PFM-modulated at different frequencies in the optical transmitters 2A and 2B, even if they are combined in the optical fiber 5, they can be demultiplexed by the bandpass filter 8 in the optical receiver 6. , each can be monitored as separate images. As a result, only one optical fiber 5 is required to connect the optical multiplexer 4 installed on the surveillance camera side and the optical receiver 6 in the intensive monitoring room, even when the distance between the monitoring point and the intensive monitoring room is long. , transmission lines can be constructed easily and at low cost.

〔Effect of the invention〕

As explained above, the present invention modulates the imaging signals from surveillance cameras at multiple locations at different frequencies, multiplexes the signals, and transmits them through an optical fiber, and the optical receiver demultiplexes the transmitted optical signals. Since each imaging signal is monitored separately, the transmission line connecting multiple remote monitoring points and the central monitoring room can be configured with a single optical fiber, making it easy and inexpensive to install the transmission line. There is an effect that can be built on.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention. IA, IB... Surveillance camera, 2A, 2B... Optical transmitter, 3A, 3B... Optical fiber, 4... Optical multiplexer,
5... Optical fiber, 6... Optical receiver, 7... Photodetector, 8... Bandpass filter, 9A, 9B... Demodulator, 10A, IOB... Monitor.

Claims (1)

[Claims] 1. Surveillance cameras installed at multiple locations, multiple optical transmitters that modulate and output the imaging signals of these surveillance cameras at different frequencies, and a system that combines the optical signals output from each optical transmitter. a multiplexer, an optical fiber connected to the multiplexer and extended to a central monitoring room, and demultiplexing means for demultiplexing the optical signal transmitted through the optical fiber into each of the frequencies; 1. A remote monitoring optical transmission device comprising a plurality of demodulators that demodulate each demultiplexed optical signal, and a monitor that displays each demodulated signal as an image.