JPH06224881A - Optical transmission system and transmitter/receiver for the same - Google Patents

Abstract

PURPOSE:To easily and efficiently perform the maintenance management, fault dealing and security management of broadcasting facilities by efficiently trans mitting the video signals of plural channels, the voice signals of plural channels or plural digital signals from the broadcasting place of a place to be monitored to a monitoring place without being affected by a strong electromagnetic field. CONSTITUTION:An analog signal or a digital signal inputted by a transmitter/ receiver 1 is modulated by an SWFM system and turned to an SWFM signal, the SWFM signal is converted to the optical signal of a previously set wavelength by using EGO conversion later, the optical signal is transmitted to a transmitter/receiver 2 by optical fiber cables 3 and 4, the optical signal transmitted by the optical fiber cables 3 and 4 is fetched by this transmitter/receiver 2 and converted to the SWFM signal by using ODE conversion later, and the analog signal or digital signal is reproduced by the SWFM system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission system for transmitting, for example, a plurality of channels of video signals and a plurality of channels of audio signals by optical signals and transmitting / receiving devices of the optical transmission system.

[Summary of the Invention] The present invention is a system suitable for optical transmission of signals between, for example, a monitoring station and a monitored station. For example, a video signal or an audio signal obtained at the monitored station can be obtained. SWFM for analog or digital signals
(Square Wave Frequency Modulation) method and E / O
After converting to an optical signal by the conversion method, this optical signal is transmitted to the monitoring station by an optical fiber cable, and the transmitted monitoring station side takes in the optical signal and uses the O / E conversion method and the SWFM method to detect each optical signal. A signal is demodulated to reproduce a video signal, an audio signal, or a digital signal. As a result, video signals, audio signals, or digital signals can be efficiently transmitted from the monitored place to the monitored place without being affected by the strong electromagnetic field. It is easy and efficient.

Also, after converting several channels of analog signals and several channels of digital signals into optical signals of different wavelengths by the SWFM system and the E / O conversion system, these are multiplexed and the multiplexed optical signals are converted into optical signals. The signal is transmitted to the monitoring station by a fiber cable and the multiplexed optical signal is taken in at the monitoring station side, and the O / E conversion method and SWF are used.
The present invention realizes an optical multiplex transmission system which demodulates each of the optical signals by the M method and reproduces analog signals of several channels and digital signals of several channels.

Further, for example, when an analog signal or a digital signal is transmitted from the monitored place to the monitored place through the optical fiber cable as described above, the same optical fiber is sent from the monitored place to the monitored place. It is intended to realize bidirectional optical transmission in which control data and the like are optically transmitted via a cable.

[0005]

2. Description of the Related Art In a broadcasting station, from the viewpoint of maintenance and management of broadcasting equipment, troubleshooting, security management, etc., a video or audio indicating the operating status of the broadcasting station, which is the monitored station, is displayed on the monitoring station side. There is a demand to monitor.

Conventionally, for such monitor monitoring, electric signals such as video and audio captured by a video camera or a microphone have been transmitted by a coaxial cable.

[0007]

However, in the above-mentioned conventional technique, since the video signal and the audio signal of the monitored place are transmitted to the monitoring place by the coaxial cable, the image and the sound are converted into the image and the sound by the fogging of the high frequency facility such as electric noise. There was a problem that interference occurred. That is, although video signals and audio signals can be multiplexed by an electric signal system, when the multiplexed electric signals are amplified, interfering waves due to a strong electromagnetic field cause intermodulation in the amplifier to cause a video image. There is a problem in that it interferes with signals and voice signals.

Therefore, in order to solve the above problems,
A method of converting a video signal or an audio signal into an optical signal and optically transmitting the optical signal is also conceivable. However, in the conventional optical transmission method, an optical intensity modulation (IM) method is adopted, so that E / O (electrical signal / optical signal) is used. ) There is a problem that the converter is required to have linearity, the E / O converter becomes expensive, and if the linearity is not sufficient, the transmission signal is deteriorated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a plurality of channels of video signals, a plurality of channels of audio signals, or a plurality of channels of digital data signals without being affected by a strong electromagnetic field. An optical transmission system and a transmission / reception device for an optical transmission system, which can perform bidirectional transmission with an efficient and inexpensive configuration, and can easily and efficiently perform maintenance management, failure response, security management, etc. of broadcasting equipment. To provide.

[0010]

In order to achieve the above object, the optical transmission system according to the invention of claim 1 is a SWFM for modulating an analog signal and / or a digital signal by a SWFM method to generate a SWFM signal. Signal generating means, E / O converting means for converting the SWFM signal into an optical signal having a preset wavelength and outputting the optical signal to the optical fiber cable, and converting the optical signal transmitted by the optical fiber cable into the SWFM signal. It is characterized by comprising an O / E conversion means for performing the above and a signal reproducing means for reproducing an analog signal or a digital signal from the SWFM signal.

The optical transmission system according to a second aspect of the present invention includes a plurality of SWFM signal generating means for generating a SWFM signal by modulating a plurality of analog signals and / or digital signals by the SWFM method. Each SWFM
A plurality of E / O conversion means for converting a signal into an optical signal having a wavelength preset for each signal, and an optical combining means for combining the optical signals of the respective wavelengths to generate a multiplexed optical signal and outputting it to an optical fiber cable. An optical signal distribution means for distributing the multiplexed optical signal transmitted by the optical fiber cable, a plurality of O / E conversion means for converting each distributed optical signal into a SWFM signal, and an analog signal from the SWFM signal or Signal reproducing means for reproducing a digital signal.

Further, according to a third aspect of the present invention, there is provided a transmitting / receiving device of an optical transmission system, wherein one or a plurality of analog signals and / or digital signals are modulated by the SWFM system and S is used.
One or a plurality of SWFM signal generating means for generating a WFM signal, an E / O converting means for each SWFM signal for converting the generated one or a plurality of SWFM signals into an optical signal of a preset wavelength, and converting The combined optical signal which outputs the multiplexed optical signal obtained by combining the converted optical signal or the converted optical signal to the optical fiber cable and distributes the multiplexed optical signal input from this optical fiber cable, and the distributed optical signal It is characterized by comprising O / E conversion means for each optical signal to be converted into a SWFM signal, and signal reproduction means for reproducing an analog signal or a digital signal from this SWFM signal.

[0013]

When a video signal or an image signal is transmitted using a coaxial cable, the effect of shielding external noise such as a strong electromagnetic field is low, so that the multiple electrical signal system is likely to be interfered with. In the present invention, by using the optical fiber transmission method, a method that is not affected by the induction of external noise can be achieved.
A conventional optical transmission system uses an optical intensity modulation (IM) system. However, this requires linearity in the E / O converter, the converter becomes expensive, and the linearity is not sufficient. , Deterioration of the transmission signal occurs. In the present invention, by performing the pre-processing for converting the multiplexed electric signal into a digital signal by using the SWFM system, an inexpensive E / O dedicated to digital is provided.
A converter can be used, and characteristic deterioration due to transmission can be prevented.

Further, since it is possible to perform multi-wavelength optical transmission with one optical fiber, it is possible to increase the number of transmission channels when optical transmission is performed from one direction. Moreover, by transmitting the optical information signal from both ends of the transmission path, a bidirectional communication system can be configured.

[0015]

1 is a block diagram showing an embodiment of an optical transmission system according to the present invention.

The optical transmission system shown in this figure is laid between the transmitter / receiver 1 provided at the monitored place, the transmitter / receiver 2 provided at the monitor, and the transmitter / receiver 1 and the transmitter / receiver 2. Two optical fiber cables 3 and 4 are provided, and after the transmitter / receiver 1 at the monitored place multiplexes the three-channel video signal and the six-channel audio signal into an optical signal, each optical fiber cable On the other hand, the transmitter / receiver 2 of the monitoring station receives the optical signals supplied via the optical fiber cables 3 and 4 and reproduces the video signals of 3 channels and the audio signals of 6 channels while transmitting the signals by 3 and 4. . In addition, the transmitter / receiver 2 converts 2-channel digital data into an optical signal and supplies the optical signal to the transmitter / receiver 1 of the monitored place by the optical fiber 4, while the transmitter / receiver 1 of the monitored place digitally converts the supplied optical signal into a digital signal. Convert to data and play.

In the following, an example of an optical multiplex transmission system is shown in FIG.
An optical bidirectional transmission system will be described with reference to the block diagram on the side of the optical fiber cable 3 in FIG.

The transmitter / receiver 1 includes a first transmission processing circuit 5
A second transmission processing circuit 6, a first optical multiplexer / demultiplexer 7, and a third optical multiplexer / demultiplexer 7.
A transmission processing circuit 8, a reception processing circuit 9, and a second optical multiplexer / demultiplexer 10 are provided, and the first transmission processing circuit 5, the second transmission processing circuit 6, and the first optical multiplexer / demultiplexer 7 provide a first image. Signal and second video signal, first and second audio signals, and third and fourth
The audio signals are respectively multiplexed, modulated by the SWFM method and converted into an optical signal of 850 nm and an optical signal of 1300 nm, which are then optical multiplexed and transmitted to the transmitting / receiving device 2 by one optical fiber cable 3. The third transmission processing circuit 8 multiplexes the third video signal with the fifth audio signal and the sixth audio signal, modulates the signals by the SWFM method, and converts them into an optical signal of 850 nm. It transmits to the transmission / reception apparatus 2 by the other optical fiber cable 4 via the wave filter 10. Furthermore, 13 of the first digital data and the second digital data supplied from the monitoring station via the optical fiber cable 4 and the second optical multiplexer / demultiplexer 10.
The optical signal of 00 nm is received, converted into an electric signal by the reception processing circuit 9, and output.

The first transmission processing circuit 5, as shown in FIG.
Video transmission unit circuit 11, first audio transmission unit circuit 12, second audio transmission unit circuit 13, SWFM
A modulation circuit 14 and an E / O converter 15 are provided, and the first video signal and the first and second audio signals are taken in, and the first video signal, the first and second audio signals, and the like. After each signal processing, it is multiplexed and modulated by the SWFM system,
850 after E / O conversion (electrical signal / optical signal conversion)
It is converted into an optical signal of nm and is supplied to the first optical multiplexer / demultiplexer 7.

The video transmission unit circuit 11 takes in the first video signal and amplifies it to a preset level, and an amplifier circuit 16 that outputs the first video signal.
A clamp circuit 17 that clamps a video signal and a low-pass filter circuit 18 that low-pass filters the first video signal output from the clamp circuit 17 at a preset cutoff frequency to prevent interference with an audio subcarrier. I have it.

Further, the first voice transmitting unit circuit 12 is
A pre-emphasis circuit 19 that takes in the first audio signal and performs pre-emphasis processing for noise reduction, and a VC that generates an audio subcarrier of 5 MHz modulated by the first audio signal output from the pre-emphasis circuit 19.
O circuit (voltage controlled oscillator) 20 and this VCO circuit 20
A bandpass filter circuit 21 that performs bandpass filtering at a preset bandpass frequency of the oscillation signal output from

Further, the second voice transmission unit circuit 13 is
A pre-emphasis circuit 22 that takes in a second audio signal and performs a pre-emphasis process for noise reduction, and a VCO that generates a 6.5 MHz audio subcarrier modulated by the second audio signal output from the pre-emphasis circuit 22. A circuit 23 and a bandpass filter circuit 24 for bandpass filtering the oscillation signal output from the VCO circuit 23 at a preset bandpass frequency.
It has and.

The SWFM modulation circuit 14 has a VCO circuit which oscillates at a frequency according to the level of the input signal.
A video signal output from the video transmission unit circuit 11,
The VCO circuit is oscillated based on the composite signal in which the audio signal output from the first audio transmission unit circuit 12 and the audio signal output from the second audio transmission unit circuit 13 are combined at a ratio of 60:20:20. , About 14MHz
SWFM signal is generated and is supplied to the E / O converter 15.

FIG. 3 shows the spectrum of the composite signal. In addition, this composite signal is shown in FIG.
With the waveform as shown in FIG. 4A, the SWFM signal having the waveform as shown in FIG. 4B is generated, and this is the E / O converter 15.
Is supplied to.

The E / O converter 15 is equipped with a digital optical transmission module using an LED composed of AlGaAs (aluminum gallium arsenide), and has a SWFM.
Based on the SWFM signal output from the modulation circuit 14,
As shown in FIG. 5, an optical signal having a wavelength of 850 nm is generated and supplied to the first optical multiplexer / demultiplexer 7.

The second transmission processing circuit 6 is constructed similarly to the above-mentioned first transmission processing circuit 5, and takes in the second video signal and the third and fourth audio signals, and at the same time, these second video signals. The signal and the third and fourth audio signals are respectively processed, multiplexed, and modulated by the SWFM system, and then E / O.
After conversion (electrical signal / optical signal conversion), as shown in FIG.
It is converted into an optical signal of 00 nm and supplied to the first optical multiplexer / demultiplexer 7.

The first optical multiplexer / demultiplexer 7 includes a first transmission processing circuit 5
From the second transmission processing circuit 6 and the optical signal having a wavelength of 1300 nm output from the second transmission processing circuit 6 are multiplexed, and these are multiplexed at one end of one optical fiber cable 3 as shown in FIG. Make it incident.

Each of the optical fiber cables 3 and 4 is composed of a graded index matrix mode fiber. The optical fiber cable 3 takes in the optical signal emitted from the first optical multiplexer / demultiplexer 7 of the transmitter / receiver 1 and transmits it to the transmitter / receiver 2. Further, the optical fiber cable 4 takes in an optical signal output from the second optical multiplexer / demultiplexer 10 of the transmitting / receiving apparatus 1, transmits the optical signal to the transmitting / receiving apparatus 2, and outputs the optical signal from the transmitting / receiving apparatus 2, as described later. The optical signal is transmitted and supplied to the transceiver 1.

In this case, as the optical fiber cables 3 and 4, optical fibers having a transmission loss of about 2.0 dB at a wavelength of 850 nm and about 0.3 dB at a wavelength of 1300 nm per 1 km are used. It is used as one optical fiber cable 3 and 4 by jointing with a connector.

Even in this case, the transmission loss due to the joint is about 1.5 dB, which is about 3.5 dB at the wavelength of 850 nm and about 2.0 dB at the wavelength of 1300 nm. , Sufficient C / N can be secured.

The third transmission processing circuit 8 is constructed similarly to the first transmission processing circuit 5 and the second transmission processing circuit 6 described above, and outputs the third video signal, the fifth and sixth audio signals. With the third video signal and the fifth and sixth video signals.
After processing each of the audio signals and multiplexing,
After being modulated by the method, it is converted into an optical signal of 850 nm by E / O conversion (electrical signal / optical signal conversion), and this is supplied to the second optical multiplexer / demultiplexer 10.

Further, the reception processing circuit 9 takes in an optical signal having a wavelength of 1300 nm output from the second optical multiplexer / demultiplexer 10, performs O / E conversion (optical signal / electrical signal conversion) on the optical signal, and then uses the SWFM method. After demodulating and separating into two digital data by filtering, signal processing is performed to reproduce the first digital data and the second digital data, and this is output.

The second optical multiplexer / demultiplexer 10 causes the optical signal having a wavelength of 850 nm output from the third transmission processing circuit 8 to enter one end of the optical fiber cable 4. Further, the optical signal of wavelength 1300 nm supplied from the optical fiber cable 4 is supplied to the reception processing circuit 9.

The transmitter / receiver 2 at the monitoring station includes a first optical multiplexer / demultiplexer 25, a first reception processing circuit 26, and a second reception processing circuit 2.
7, second optical multiplexer / demultiplexer 28, and third reception processing circuit 29
And a transmission processing circuit 30, and SWFM demodulates an optical signal supplied via each optical fiber cable 3 and 4 to reproduce a 3-channel video signal and a 6-channel audio signal. Also, the first digital data and the second digital data are combined and transmitted to the monitored place.

The first optical multiplexer / demultiplexer 25 takes in the optical signal emitted from the optical fiber cable 3, divides the optical signal of wavelength 850 nm and the optical signal of wavelength 1300 nm, as shown in FIG. The signal is supplied to the first reception processing circuit 26 and the optical signal having a wavelength of 1300 nm is supplied to the second reception processing circuit 27.

The first reception processing circuit 26 is, as shown in FIG. 9, an O / E converter 31, a SWFM demodulation circuit 32, a video receiving unit circuit 33, and a first audio receiving unit circuit 34.
And a second audio receiving unit circuit 35, which takes in an optical signal of 850 nm output from the first optical multiplexer / demultiplexer 25 and O / E converts it (optical signal / electrical signal conversion), After demodulating by the SWFM method and further separated into a video signal and two audio signals by filtering, signal processing is performed to reproduce the first video signal, the first audio signal, and the second audio signal.

The O / E converter 31 is a photodiode (for example, avalanche photodiode or PIN) composed of InGaAs (indium gallium arsenide).
It is equipped with a digital optical receiver module using a photo diode) and takes in an optical signal with a wavelength of 850 nm emitted from the first optical multiplexer / demultiplexer 25, and
E conversion is performed to reproduce the SWFM signal, and this is supplied to the SWFM demodulation circuit 32.

The SWFM demodulation circuit 32 temporarily converts the SWFM signal into a PFM (pulse FM) signal having a constant pulse width, and then demodulates it through an interpolation filter having a low-pass filter structure.

In this case, if the PFM signal has a waveform as shown in FIG. 10 (a), the composite signal having the waveform shown in FIG. 10 (b) is reproduced by passing through the low-pass filter, which is the video receiving unit. Circuit 33 and the first
It is supplied to the audio receiving unit circuit 34 and the second audio receiving unit circuit 35.

The video receiving unit circuit 33 includes a low-pass filter circuit 36 for low-pass filtering the composite signal output from the SWFM demodulation circuit 32 at a preset cutoff frequency to extract a video signal,
An amplifier circuit 37 that amplifies the video signal output from the low-pass filter circuit 36 is provided, and the composite signal output from the SWFM demodulation circuit 32 is taken in, low-pass filtered, and then amplified to obtain the first video image. Play the signal and output it.

The first voice receiving unit circuit 34 is
A bandpass filter circuit 38 that extracts the 5 MHz audio subcarrier modulated by the audio signal by bandpass filtering the composite signal output from the SWFM demodulation circuit 32 at a preset bandpass frequency.
A DET circuit 39 for FM demodulating the extracted audio subcarrier to reproduce the first audio signal; and the DET circuit 3
And a de-emphasis circuit 40 for de-emphasising the first audio signal output from the first audio signal 9 to reduce noise.

The second voice receiving unit circuit 35 is
A bandpass filter circuit 41 that extracts a 6.5 MHz audio subcarrier by bandpass filtering the composite signal output from the SWFM demodulation circuit 32 at a preset bandpass frequency, and the output from this bandpass filter circuit 41. The DET circuit 42 which reproduces the second audio signal by FM demodulating the audio subcarrier to be reproduced, and the DE
And a de-emphasis circuit 43 that reduces noise by performing de-emphasis processing on the second audio signal output from the T circuit 42.

The second reception processing circuit 27 has the same structure as the first reception processing circuit 26 described above, and takes in an optical signal having a wavelength of 1300 nm output from the first optical multiplexer / demultiplexer 25 and outputs it. O / E conversion (optical signal / electrical signal conversion)
After that, the signal is demodulated by the SWFM method, further filtered to be separated into a video signal and two audio signals, and then signal processed to reproduce the second video signal, the third audio signal, and the fourth audio signal.

The second optical multiplexer / demultiplexer 28 has the same structure as the second optical multiplexer / demultiplexer 10 described above, and as shown in FIG.
An optical signal of 0 nm is captured and supplied to the third reception processing circuit 29, and at the same wavelength 1 output from the transmission processing circuit 30.
An optical signal of 300 nm is supplied to the optical fiber cable 4.

The third reception processing circuit 29 has the same structure as the first reception processing circuit 26 and the second reception processing circuit 27 described above, and has the wavelength 8 output from the second optical multiplexer / demultiplexer 28.
It takes in a 50 nm optical signal, performs O / E conversion (optical signal / electrical signal conversion) on it, demodulates it with the SWFM method, and further separates it into a video signal and two audio signals by filtering, and then performs signal processing. The third video signal, the fifth audio signal, and the sixth audio signal are reproduced and output.

Further, the transmission processing circuit 30 takes in the first digital data and the second digital data. The first digital data is a signal having a high transmission rate and has the same band of about 4.2 MHz as the video signal. The second digital data is a signal having a low transmission rate and has the same band of about 10 kHz as the audio signal. These signals are multiplexed, modulated by the SWFM system, and further E / O converted (electrical signal / optical signal conversion) to be converted to an optical signal of 1300 nm,
This is supplied to the second optical multiplexer / demultiplexer 28.

<< Characteristics of Embodiments >> Then, as a result of making and experimenting with an actual device having the above-mentioned structure, the video frequency amplitude characteristic shown in FIG. 11, the DG characteristic (differential gain characteristic) of the image shown in FIG. The DP characteristic (differential phase characteristic) of the image shown in FIG. 13 was obtained, the audio signal frequency amplitude characteristic shown in FIG. 14 was obtained, and the S / N characteristic and the distortion rate characteristic shown in FIG. 15 were obtained.

As is clear from FIGS. 11 to 15, in the video signal characteristics, -3 dB at 4.2 MHz as frequency amplitude characteristics, 3% as DG characteristics, 5 deg as DP characteristics, and 50 dB as S / N are secured. We were able to.

Regarding the audio signal characteristics, it was possible to secure a frequency amplitude characteristic of about -1 dB at 10 kHz, a distortion rate of 1.5% or less at 1 kHz, and an S / N of 50 dB or more.

All of these characteristics are sufficient to transmit a video signal and an audio signal for monitoring.

The digital data transmission system has the same characteristics as those of the video signal and audio signal transmission systems.
It was confirmed that the transmission characteristics of digital data were sufficient.

As described above, in the present embodiment, the 3-channel video signal and the 6-channel audio signal obtained by the transmitter / receiver 1 of the monitored place are subjected to the SWFM method and the E signal.
After the optical signals of different wavelengths are converted by the I / O conversion method, the optical signals are multiplexed, and these optical signals are transmitted / received by the optical fiber cables 3 and 4 at the monitoring station.
The optical signal is received by the transmitter / receiver 2 and separated into optical signals of respective wavelengths, and then the optical signals are demodulated by the O / E conversion method and the SWFM method to generate a 3-channel video signal, Since the audio signal of the channel is reproduced, the video signal of multiple channels and the audio signal of multiple channels can be efficiently transmitted from the monitored place to the monitoring place without being affected by the strong electromagnetic field. This makes it possible to efficiently perform maintenance management of broadcasting equipment, troubleshooting, and security management.

In addition, when transmitting the video signal or the audio signal, bidirectional transmission of 2-channel digital data of the monitoring station to the monitored station is possible, and one of the 2-channel digital data is a high quality digital information signal. Used for
By using the other as a control signal, it is possible to efficiently perform maintenance management of the broadcasting equipment, troubleshooting, and security management.

Further, in this embodiment, since the square wave SWFM signal having the duty ratio of 50% is E / O converted to generate the optical signal, the VCO circuit provided in the SWFM modulation circuit 14 is used. Can be easily generated by the SWFM demodulation circuit 32, and the SWFM signal is temporarily generated by the PFM (pulse F
After being converted into the M) signal, it can be easily demodulated by passing through an interpolation filter having a low-pass filter configuration.

Further, since the SWFM signal having the duty ratio of 50% is used, the required transmission line bandwidth can be narrowed as compared with the case of transmitting the PFM signal having the constant pulse width. The E / O converter 15 can be configured by using an LED that is cheaper than a diode.

Further, in this embodiment, since the SWFM signal which is a pulse signal is used, the E / O converter 1
5 and the O / E converter 31 can use a commercially available module for digital transmission, which can significantly reduce the manufacturing cost of the entire device.

Further, since the linearity of the light emitting element or the light receiving element is not affected, it is possible to improve the DG characteristic and the DP characteristic of the video signal and the influence of the characteristic change due to the temperature characteristic of the light emitting element or the light receiving element. You can prevent them from suffering.

Further, in this embodiment, the light emitting element can be always used in the rated output state, so that the transmission distance can be extended.

The O / E converter 31 may be composed of a photodiode having sensitivity only to a specific light wavelength. In this case, it is not necessary for the first and second optical multiplexers / demultiplexers 25 and 28 to separate the specific wavelengths.
In addition, after the specific wavelengths are separated by the first and second optical multiplexers / demultiplexers 25 and 28, the optical signal of the specific wavelength is detected by the O / E converter 31 composed of a photodiode having sensitivity only to the specific wavelength. It may be done.

It is needless to say that a plurality of digital signal systems can be used for optical multiplex transmission and a plurality of analog signal systems can be used for optical bidirectional transmission.

<< Description of Application Example >> FIG. 16 is a block diagram showing an example of a monitoring system to which the above-described embodiment is applied. In this figure, the same components as those of FIG. 1 are designated by the same reference numerals.

In this monitoring system, the unmanned second broadcasting station monitors, maintains and manages the second broadcasting station, and the first broadcasting station
The control data and the like are output from the broadcasting station side to the second broadcasting station side for control.

Therefore, in this surveillance system, the transmission / reception device 1 provided on the side of the second broadcasting station serving as the monitored station and the transmission / reception device 2 provided on the side of the first broadcasting station serving as the monitoring station are installed. Of the two optical fiber cables 3, 4,
Bidirectional communication is performed using the wavelength 1300 nm of one optical fiber cable 4 for data (for example, digital control data) transmission.

The monitoring system shown in this figure includes a second broadcasting station device (monitored station device) 50, a transceiver device 1, two optical fiber cables 3 and 4, a transceiver device 2, and a first broadcasting station. And a device 51 for converting a video signal, a camera audio signal and the like obtained by the second broadcasting station device 50 into an optical signal by the transmitting / receiving device 1 of the second broadcasting station,
This is transmitted to the first broadcasting station side via the optical fiber cables 3 and 4, and the transmission / reception device 2 provided on the first broadcasting station side
This is received by the first broadcasting station equipment (monitoring station equipment)
51 to monitor.

The second broadcasting station device 50 synthesizes a plurality of cameras 52 provided for monitoring the broadcasting devices and for outdoor monitoring on the monitored site side with four screens of images taken by each camera 52, and A four-screen synthesizing circuit 53 for supplying an audio signal to the transmitting / receiving device 1, a CCD camera 54 used as a general-purpose photographing device, a driving circuit 55 for driving the CCD camera 54, and a video signal obtained by the driving circuit 55. Also, the video signal output from the 4-screen synthesis circuit 53 is sequentially switched based on the control data output from the transceiver 1, and the transceiver 1
And a monitor device 57 that captures the video signal output from the transmitting / receiving device 1 and displays it on the screen.

The transmitter / receiver 1 has the same structure as that shown in FIG. 1 and takes in a video signal, a camera audio signal and a monitor audio signal output from the second broadcasting station device 50, and uses them in the SWFM system. After it is modulated with, it is multiplexed and converted into an optical signal, and this is converted into each optical fiber cable 3, 4
The optical signal supplied from the first broadcasting station via the optical fiber cable 4 is supplied to the transmission / reception device 2 via the SW.
Control data (digital data) after demodulation by FM method
Is supplied to the second broadcasting station device 50.

Each of the optical fiber cables 3 and 4 has the same structure as that of the optical fiber cables 3 and 4 shown in FIG. 1. The optical signal output from the transmitter / receiver 1 is taken in and the transmitter / receiver 2 receives the optical signal. To the transmitter / receiver 2, or the optical signal output from the transmitter / receiver 2 is captured and supplied to the transmitter / receiver 1.

The transmitter / receiver 2 is also constructed in the same manner as that shown in FIG. 1, and after demodulating the optical signal supplied through the respective optical fiber cables 3 and 4 by the SWFM system, the video signal and the camera are obtained. It is separated into an audio signal and supplied to the first broadcasting station equipment 51, or control data etc. output from the first broadcasting station equipment 51 is taken in and modulated by the SWFM system, and then converted into an optical signal. , Which is supplied to the transmission / reception device 1 via the optical fiber cable 4.

The first broadcasting station equipment 51 is, for example, a monitor device 60 for displaying data indicating surveillance data of a broadcasting device, and a camera for photographing the display contents of the monitor device 60 and supplying the video signal to the transmitting / receiving device 2. 61, a voice switch circuit 62 that takes in a camera voice signal output from the transmitting / receiving device 2 and selects any one of the camera voice signal, the program voice signal, and the air monitor voice signal, and the voice switch circuit 62. And an amplifier circuit 63 for amplifying the audio signal
A speaker 64 that converts the audio signal amplified by the audio into audio and outputs the audio; a video switch circuit 65 that takes in the multi-channel video signals and audio signals output from the transceiver 2 and selects the audio signals; Placed in
A monitor device 66 that captures and displays the video signal selected by the video switch circuit 65, and a monitor device 67 that is arranged in the guard room and captures and displays the video signal selected by the video switch circuit 65 are provided. .

On the side of the second broadcasting station, each camera 52
The video signal obtained by the CCD camera 54 and the camera audio signal are supplied to the transmitter / receiver 1, and the video signal output from the transmitter / receiver 1 is captured and displayed on the monitor 57.

On the side of the first broadcasting station, control data is generated and supplied to the transmitting / receiving device 2, or the monitoring screen displayed on the monitor device 60 is photographed by the camera 61 and the video signal is transmitted / received. While supplying to the device 2,
Video signals and audio signals output from the transmitter / receiver 2 are displayed on the monitor devices 66 and 67, and the transmitter / receiver 2
Select the camera audio signal output from the speaker 64
Output from.

As described above, in this monitoring system, the second broadcasting station equipment (monitored station equipment) 5 is used by using the transmission / reception apparatus 1, the respective optical fiber cables 3 and 4, and the transmission / reception apparatus 2 shown in FIG.
The communication between 0 and the first broadcasting station equipment (monitoring station equipment) 51 is supported, so that multiple channels of video can be transmitted from one broadcasting station to the other broadcasting station without being affected by strong electromagnetic fields. Signals, audio signals of multiple channels, or control data (digital data) can be efficiently transmitted, which enables maintenance and troubleshooting of broadcasting equipment, troubleshooting,
Security management can be performed easily and efficiently.

In the above description, an example in which the present invention is applied as information transmission between broadcasting stations has been shown. However, it is also applicable to information transmission for monitoring buildings and premises, or audiovisual equipment in educational facilities. The present invention can be applied.

[0074]

As described above, according to the present invention, a multi-channel video signal, a multi-channel audio signal or a digital signal can be transmitted from one broadcasting station to the other broadcasting station without being affected by a strong electromagnetic field. The data can be efficiently transmitted, which enables easy and efficient maintenance and management of the broadcasting equipment, troubleshooting, and security management.
In addition, bidirectional transmission enables remote operation by transmitting control signals during transmission of audio and video signals, which enables more efficient maintenance and management of equipment, fault response, and security management. .

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed circuit configuration example of a first transmission processing circuit shown in FIG.

3 is a characteristic diagram showing a spectrum example of a video signal output from the video transmission unit circuit shown in FIG. 2 and respective audio signals output from the first and second audio transmission unit circuits.

4 is a diagram showing a waveform example of a composite signal input to the SWFM modulation circuit shown in FIG. 2 and a waveform example of a SWFM signal output from the SWFM modulation circuit.

5 is a characteristic diagram showing a spectrum example of an optical signal input to the first optical multiplexer / demultiplexer on the transmitter side shown in FIG.

FIG. 6 is a schematic diagram showing an operation example of the first optical multiplexer / demultiplexer shown in FIG.

FIG. 7 is a schematic diagram showing an operation example of the first optical multiplexer / demultiplexer shown in FIG.

FIG. 8 is a schematic diagram showing an operation example of the second optical multiplexer / demultiplexer shown in FIG.

9 is a block diagram showing a detailed circuit configuration example of a first reception processing circuit shown in FIG. 1. FIG.

10 is a diagram showing a waveform example of a PFM signal generated in the SWFM demodulation circuit shown in FIG. 9 and a waveform example of a composite signal output from the SWFM demodulation circuit.

11 is a diagram showing video frequency amplitude characteristics of the optical transmission system shown in FIG.

12 is a diagram showing a DG characteristic of an image of the optical transmission system shown in FIG.

13 is a diagram showing a DP characteristic of an image of the optical transmission system shown in FIG.

14 is a diagram showing a voice signal frequency amplitude characteristic of the optical transmission system shown in FIG.

15 is a diagram showing S / N characteristics and distortion factor characteristics of the optical transmission system shown in FIG.

FIG. 16 is a block diagram showing an example of a monitoring system to which the optical transmission system according to the present invention is applied.

[Explanation of symbols]

 1, 2 Transmitter / receiver 3, 4 Optical fiber cable 5 First transmission processing circuit 6 Second transmission processing circuit 7, 25 First optical multiplexer / demultiplexer 8 Third transmission processing circuit 9 Reception processing circuit 10, 28 Second optical multiplexer / demultiplexer Vessel 26 first reception processing circuit 27 second reception processing circuit 29 third reception processing circuit 30 transmission processing circuit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H04J 1/00 8949-5K (72) Inventor Eiichi Kawabata 3047, Oka, Minamisaitama-gun, Saitama Prefecture 1 Japan Broadcasting Corporation, Kyōsho Kuki Radio Broadcasting Station (72) Inventor Hiroaki Ikeda 6-8-6 Sanarudai, Hamamatsu City, Shizuoka Prefecture Little Bird No. 202 (72) Inventor Lee Jinju 27-14, Fumiokacho, Hamamatsu City, Shizuoka Prefecture Suzuki Apartment A-3

Claims (3)

[Claims] 1. An S for generating an SWFM signal by modulating an analog signal and / or a digital signal by a SWFM method.
WFM signal generation means, E / O conversion means for converting the SWFM signal into an optical signal of a preset wavelength and outputting the optical signal to an optical fiber cable, and an optical signal transmitted by the optical fiber cable to S
An optical transmission system comprising: an O / E converting means for converting into a WFM signal; and a signal reproducing means for reproducing an analog signal or a digital signal from the SWFM signal. 2. A plurality of SWFM signal generating means for modulating a plurality of analog signals and / or digital signals by a SWFM method to generate a SWFM signal, and each generated SWFM signal is preset in each signal. A plurality of E / O conversion means for converting the optical signals of wavelengths, an optical combining means for combining the optical signals of the respective wavelengths to generate a multiplexed optical signal and outputting the multiplexed optical signal to an optical fiber cable, and the multiplexing transmitted by the optical fiber cable. Optical signal distribution means for distributing an optical signal, and a plurality of O's for converting each distributed optical signal into a SWFM signal
An optical transmission system, comprising: an / E conversion means; and a signal reproduction means for reproducing an analog signal or a digital signal from the SWFM signal. 3. One or a plurality of SWFM signal generating means for modulating one or a plurality of analog signals and / or digital signals by a SWFM method to generate a SWFM signal, and presetting the generated one or a plurality of SWFM signals. E / O for each SWFM signal that is converted to an optical signal of the specified wavelength
A converting means, an optical combining / distributing means for outputting a converted optical signal or a multiplexed optical signal obtained by combining the converted optical signals to an optical fiber cable and distributing the multiplexed optical signal input from the optical fiber cable; An optical transmission system comprising: an O / E conversion unit for each optical signal that converts the generated optical signal into a SWFM signal; and a signal reproduction unit that reproduces an analog signal or a digital signal from the SWFM signal. Transceiver device.