JP4411405B2 - Real-time broadcasting system and real-time broadcasting signal transmission method - Google Patents

Description

  The present invention relates to a real-time broadcast system and a real-time broadcast signal transmission method for realizing real-time communication of broadcast signals using existing optical fiber communication paths.

With the development of communication systems and broadcasting equipment, audio and video signals are sent in real time from all over the world. A technique for efficiently using an expensive transmission line such as satellite communication has been established by a signal compression technique and a high-speed processing. (Patent Document 1)
JP 2003-018559 A JP 2003-043529 A JP2002-258335

By the way, the conventional techniques as described above have the following problems to be solved.
As noticed in relay broadcasting between two points using artificial satellites, the time delay of the transmission signal may prevent smooth conversation. That is, the voice uttered at one point is compressed by the voice processing circuit and transmitted toward the communication path. When this is received at the other point, the compressed signal is expanded and then converted into an acoustic signal. For this reason, a time delay of one second or more may occur before the voice reaches the other party.

  When a signal is unilaterally transmitted from one to the other, no major problem occurs, but in the case of bidirectional communication, this time delay becomes a major obstacle. Of course, even in the case of unilateral transmission of signals, for example, in broadcasts that receive and edit relay images at multiple points in a batch or perform multi-way relay, the time of each relay image Delay variation can be a problem.

  The present invention has been made paying attention to the above points, and an object thereof is to provide a real-time broadcast system and a real-time broadcast signal transmission method for realizing real-time communication of broadcast signals using existing optical fiber communication paths. To do.

The present invention solves the above problems by the following configuration.
<Configuration 1>
An optical fiber communication path that satisfies a predetermined standard, selected from existing communication paths connecting two points, and an uncompressed digital broadcast signal that is provided at one of the two points. An electric / optical converter that converts the optical signal into an optical fiber communication path, and the digital broadcasting provided at the other of the two points and output from the optical fiber communication path An optical / electrical converter for converting a signal from an optical signal to an electrical signal, and the optical fiber communication path compensates the optical signal level transmitted to the optical fiber communication path at one or both ends thereof. A real-time broadcasting system, wherein a new optical amplifier not included in the optical fiber communication path is inserted.

  In the present invention, a broadcast signal is transmitted in a so-called real time with a time delay equal to or less than an allowable value. For transmission of broadcast signals, an existing optical fiber communication path is used. The existing optical fiber communication path is a wide area communication line provided for general users by a telephone company or the like. It is not a dedicated communication channel set up exclusively for real-time broadcasting. A predetermined reference optical communication path required for real-time broadcasting is selected from existing optical fiber communication paths. In general, an optical fiber and a repeater or the like for satisfying its transmission characteristics are appropriately inserted in an existing optical fiber communication path. In the present invention, the entire optical fiber communication path is regarded as a passive circuit, and transmission characteristics viewed from both ends are compensated by a new optical amplifier attached externally.

<Configuration 2>
2. The real-time broadcast system according to Configuration 1, wherein the optical amplifier is a Raman amplifier.

  If a Raman amplifier is inserted at one or both ends of an optical fiber communication path, a digital broadcast signal transmitted through a long span existing optical fiber communication path can be freely amplified to a desired level with low noise and high gain. In addition, the existing optical fiber communication path is characterized in that a broadcast signal can be transmitted between any two points as long as predetermined criteria such as a transmission delay and a transmission band are satisfied. Therefore, for example, there is an effect that various existing communication channels such as a so-called dark fiber that is not used even if laid can be widely used. In addition, since the uncompressed digital broadcast signal is transmitted as it is as an optical signal, the transmission delay of the entire communication path can be minimized.

<Configuration 3>
In the real-time broadcasting system according to Configuration 1 or 2, the optical fiber communication path includes a plurality of existing optical fiber communication paths that are connected in cascade and connect two points and satisfy a predetermined standard. A real-time broadcast system in which an optical amplifier for compensating a level of an optical signal transmitted to the optical fiber communication path is inserted into one or both ends of the optical fiber communication path.

  When the distance between two points is long, a plurality of existing optical fiber communication paths that satisfy a predetermined standard are connected in cascade. At this time, since an optical amplifier is inserted at one end or both ends for each optical fiber communication path, the necessary and sufficient gain is compensated as a whole. Of a plurality of optical fiber communication channels, a short communication channel does not require a large gain compensation. Therefore, it is preferable to perform gain compensation with an optimum amplifier according to the length of the communication channel.

<Configuration 4>
In the real-time broadcasting system according to Configuration 1, at one of the points, a plurality of electric / optical signals that convert uncompressed digital broadcasting signals output from different signal sources from electric signals to optical signals of different wavelengths, respectively. A converter and a multiplexer that collects the optical signals output from these electrical / optical converters and sends them to the optical fiber communication path, and transmits the optical fiber communication path to the other point. A real-time broadcasting system comprising: a duplexer that separates optical signals of different wavelengths, and a plurality of optical / electrical converters that convert the separated optical signals into electrical signals.

  Since the uncompressed digital broadcast signals output from a plurality of signal sources are converted into optical signals and multiplexed, the optical fiber communication path can be effectively used for real-time transmission of broadcast signals of a plurality of channels. In addition, since it is multiplexed after being converted into an optical signal, high-quality broadcast signal transmission with little transmission delay is possible for all channels. Further, the communication path can be effectively used by multiplexing.

<Configuration 5>
5. The real-time broadcast system according to Configuration 4, wherein the signal sources at the one point are each composed of an asynchronous and uncompressed video signal and / or audio signal.

  As the signal source, a video signal, an audio signal, or a composite signal of the video signal and the audio signal is suitable. These signals are most required to be real-time as broadcast signals. If the signals are broadcast without being compressed, the transmission delay can be minimized. Also, if asynchronous is acceptable, phase alignment between channels is unnecessary, and transmission delay does not occur. Furthermore, there is an effect that the transmission characteristics of each channel can be optimized independently.

<Configuration 6>
An uncompressed digital broadcast signal is converted from an electric signal to an optical signal at an optical fiber communication path satisfying a predetermined standard selected from existing communication paths connecting two points and the two points. An optical / electrical converter for sending out the optical fiber communication path; and an optical / electrical converter for converting a digital broadcast signal output from the optical fiber communication path from an optical signal to an electrical signal. A real-time broadcasting system, wherein an optical amplifier for compensating an optical signal level transmitted bidirectionally through the optical fiber communication path is inserted into one end or both ends of the fiber communication path.

  Since the optical communication path can perform bidirectional signal transmission, the communication path can be used more effectively by performing bidirectional communication. When two-way communication of images and audio simultaneously, especially real-time properties are strictly required, but by transmitting an uncompressed digital broadcast signal using an optical fiber communication path and an optical amplifier that satisfy a predetermined standard, The demand can be satisfied.

<Configuration 7>
In the real-time broadcasting system according to Configuration 6, a plurality of electrical / optical converters that convert uncompressed digital broadcasting signals output from different signal sources from electrical signals to optical signals of different wavelengths, and the electrical A multiplexer that collects the optical signals output from the optical converter and sends them to the optical fiber communication path, and a demultiplexer that separates optical signals of different wavelengths transmitted through the optical fiber communication path, A real-time broadcasting system comprising a plurality of optical / electrical converters for converting the separated optical signals into electrical signals.

  By using bidirectional communication and transmitting multiplexed optical signals, the communication path can be used more effectively.

<Configuration 8>
8. The real-time broadcasting system according to any one of configurations 4 to 7, wherein each of the plurality of signal sources includes an output device for a video signal photographed by a video camera.

  If each of the plurality of signal sources is an output device for a video signal captured by a video camera, each video signal may be transmitted asynchronously. By transmitting these signals without compression, real-time broadcasting can be realized.

<Configuration 9>
In the real-time broadcasting system according to any one of Configurations 4 to 8, the digital broadcasting signal output from the plurality of signal sources is an optical signal that has been converted into an uncompressed serial bit stream, and is transmitted through the optical fiber communication path as it is. A real-time broadcasting system characterized by being transmitted.

  The uncompressed serial bitstreamed optical signal is faithfully transmitted toward the receiving side with minimal signal degradation and transmission delay by an optical fiber communication path and a Raman amplifier that satisfy a predetermined standard. This enables real-time broadcasting that does not make time delays conscious.

<Configuration 10>
In the real-time broadcasting system according to any one of Configurations 4 to 9, the predetermined reference of the optical fiber communication path is set so that a broadcast signal transmission delay time between two points is 0.3 seconds or less. A featured real-time broadcasting system.

  In real-time two-way communication, for example, the maximum allowable time delay of an audio signal is said to be 0.3 seconds. If a predetermined reference value for selecting an optical fiber communication path is set so that the broadcast signal transmission delay time between two points is 0.3 seconds or less, the required characteristics are satisfied. When a plurality of optical fiber communication channels are connected in cascade, the broadcast signal transmission delay time of these optical fiber communication channels is set to be 0.3 seconds or less.

<Configuration 11>
From the existing arbitrary communication path connecting the two points, the above two points and the arbitrary number of relay points between them are connected in order, each having a length of 200 km or less, and the waveform distortion of the digital pulse is less than the allowable value. Then, select an optical fiber communication path that satisfies the condition that the sum of the optical signal transmission delay times between the two points is 0.3 seconds or less, and between the terminals of the two adjacent optical fiber communication paths at the relay point. , For compensating the level of the optical signal transmitted to the optical fiber communication path, and insert a new optical amplifier not included in the optical fiber communication path, An optical signal that is an uncompressed digital broadcast signal and is converted into a serial bit stream is transmitted from at least one point to the optical fiber communication path, and the light is transmitted from at least the other point of the two points. Real-time broadcasting signal transmission method characterized by receiving an optical signal via the Aiba communication path and the relay point in the order.

  The number of relay points is arbitrary. The length is selected according to the quality of the optical fiber communication path. If the waveform distortion of the optical signal transmitted by the optical amplifier or the optical dispersion compensator is compensated and the deterioration of the digital signal waveform is prevented as in the configurations 11, 12, and 13, the uncompressed digital broadcast signal is obtained. A bitstreamed optical signal can be faithfully transmitted over a long distance. In addition, if an optical fiber communication path that satisfies the condition that the total of optical signal transmission delay times between two points is 0.3 seconds or less is selected, it is possible to transmit a real-time broadcast signal without applying stress.

<Configuration 12>
From the existing arbitrary communication path connecting the two points, the above two points and the arbitrary number of relay points between them are connected in order, each having a length of 200 km or less, and the waveform distortion of the digital pulse is less than the allowable value. Then, select an optical fiber communication path that satisfies the condition that the sum of the optical signal transmission delay times between the two points is 0.3 seconds or less, and between the terminals of the two adjacent optical fiber communication paths at the relay point. In order to compensate for dispersion of an optical signal transmitted to the optical fiber communication path, a new optical dispersion compensator not included in the optical fiber communication path is inserted, An uncompressed digital broadcasting signal from at least one of the two points is transmitted to the optical fiber communication path as an optical signal having two or more wavelengths converted into a serial bit stream, and at least the other of the two points. In point, real-time broadcast signal transmission method characterized by receiving an optical signal through the optical fiber communication path and the relay point in the order.

<Configuration 13>
From the existing arbitrary communication path connecting the two points, the above two points and the arbitrary number of relay points between them are connected in order, each having a length of 200 km or less, and the waveform distortion of the digital pulse is less than the allowable value. Then, select an optical fiber communication path that satisfies the condition that the sum of the optical signal transmission delay times between the two points is 0.3 seconds or less, and between the terminals of the two adjacent optical fiber communication paths at the relay point. Inserting new optical amplifiers and optical dispersion compensators for compensating the optical signal level and optical dispersion transmitted to the optical fiber communication path, which are not included in the optical fiber communication path Then, from at least one of the two points, an uncompressed digital broadcast signal, which is an optical signal having two or more wavelengths converted into a serial bit stream, is sent to the optical fiber communication path. Earth Of at least the other point, the real-time broadcast signal transmission method characterized by receiving an optical signal through the optical fiber communication path and the relay point in the order.

<Configuration 14>
The real-time broadcast signal transmission method according to any one of Configurations 11 to 13, wherein at least one of the two points is an uncompressed digital broadcast signal and two or more wavelengths converted into a serial bit stream A real-time broadcast signal transmission method characterized in that a Raman amplifier is used as an optical amplifier that asynchronously sends out the optical signal to the optical fiber communication path and inserts it into the relay point.

  A Raman amplifier is used to amplify optical signals having two or more wavelengths at a relay point all at once. If each optical signal is sent asynchronously, transmission delay due to signal buffering and synchronization processing can be avoided.

<Configuration 15>
In the real-time broadcast signal transmission method according to any one of Configurations 11 to 13, an uncompressed digital broadcast signal, which is an uncompressed digital broadcast signal from both of the two points, is asynchronously transmitted as a serial bit stream optical signal having two or more wavelengths A real-time broadcast signal transmission method, comprising: transmitting to the optical fiber communication path, and receiving an optical signal sequentially passing through the optical fiber communication path and the relay point at both of the two points.

  This method is particularly effective when transmission / reception of signals is performed bi-directionally because the transmission delay is most worrisome.

<Configuration 16>
In the real-time broadcast signal transmission method according to any one of Structures 11 to 13, on the transmission side, pixel value data groups necessary for reproducing an image captured and acquired by a camera are transmitted as they are in the acquired order. A receiving side receives the pixel value data groups in the order of acquisition, and reproduces them as they are in that order.

  The present invention is particularly effective when a signal photographed by a camera is transmitted as it is and reproduced as it is. If the buffer processing or the like is eliminated without changing the order of the pixel value data, the transmission delay can be minimized.

  The biggest cause of the time delay of the broadcast signal is the compression and expansion processing of the broadcast signal. For example, when transmitting image signals captured by a large number of television cameras installed in the field to a broadcast station, omit compression and decompression processing when using expensive communication lines such as lines using artificial satellites. I can't.

  In the present invention, an existing optical fiber communication path is used. Use dark fiber that is laid but not used. A dedicated optical fiber newly laid for the purpose of transmitting broadcast signals is not used. Since an existing optical fiber communication path is used, a communication path can be secured freely at low cost regardless of the distance between the two points. In order to perform broadcast signal real-time communication using an optical fiber as in the present invention, conventionally, it has been necessary to design and install a dedicated optical fiber communication path.

  Conventionally, when an existing optical fiber communication channel or satellite communication channel is used, it is necessary to follow the communication method of a communication company that provides the communication channel, and transmission delay cannot be avoided. The ability to design and install a dedicated optical fiber communication path other than a communication company is restricted to a limited area such as a broadcasting station. That is, for example, real-time broadcast signal transmission without a transmission delay is difficult between remote locations such as Tokyo and Nagoya.

  The existing optical fiber communication path as used in the present invention is an optical fiber communication that is already laid to connect nationwide or internationally for wide area telephone communication or wide area data communication, and is provided to the user from a communication carrier. It is a road. When two points for real-time communication are determined, there are many existing optical fiber communication paths that can connect the two points. Among them, processing is performed to select an optical fiber communication path that satisfies a certain standard for transmission delay and band characteristics. A telephone communication path or a data transmission communication path may be used as long as a certain standard is satisfied. A plurality of optical fiber communication paths satisfying a certain standard can be freely combined and used.

  In the present invention, attenuation of a transmission signal level that cannot be compensated only by an existing optical fiber communication path is compensated by providing a relay point in the communication path and newly inserting an optical amplifier. As a result, transmission characteristics that are not guaranteed in the existing communication path can be compensated. Also, transmission signal errors can be fatal for real-time communication of digital image signals. By newly inserting an optical amplifier, it is possible to secure a sufficient gain and minimize the occurrence of signal errors in the transmission signal. As the optical amplifier, a high gain optical amplifier such as a Raman amplifier is used. A Raman amplifier is known as an optical amplifier that directly amplifies an optical signal with high gain and low noise. (Patent Document 2) Further, since multiplexed optical signals can be collectively amplified, it is suitable for transmission of a real-time multiplex broadcast signal. (Patent Document 3)

  In addition to the Raman amplifier, various optical amplifiers can be used as the optical amplifier. For example, an optical amplifier such as an erbium-doped fiber amplifier (EDFA) can be employed. This is limited to optical signals with a wavelength of 1550 nanometers due to the nature of the erbium-added element, but can be used effectively if the conditions are met. In the present invention, an uncompressed digital broadcast signal is transmitted to the optical fiber communication path as described above.

  In the present invention, the broadcast signal transmitted in real time includes at least an image signal. An audio signal or other signals may be included. For example, if there is only a voice signal, real-time communication is possible in which the transmission delay can be almost ignored by the telephone communication network. However, in order to transmit an image signal taken by a video camera for a long distance, conventionally, a signal compression process has to be performed. In the present invention, such broadcast signals are transmitted uncompressed. In addition, if the communication path is about several kilometers, a dedicated line can be laid. Since dedicated lines can be freely designed, high-quality real-time communication has been possible. However, if the distance is long, such as several tens of kilometers, generally, an existing communication path must be used.

  At that time, an optical fiber communication path having a transmission band capable of transmitting a standard digital image signal with a certain high quality is selected from existing communication paths. If a new optical amplifier is inserted into this optical fiber communication path to compensate for loss, high-quality digital image signals can be transmitted in real time. The optical fiber communication path preferably has a distance of 200 km or less as one section. If it is possible to connect two points with only one communication path, an optical amplifier may be inserted at one or both ends. If the connection is made with two or more communication paths, an optical amplifier may be inserted at the connection point, that is, at the relay point. Examples of the present invention will be specifically described below.

FIG. 1 is a block diagram showing a specific example of the real-time broadcasting system of the present invention.
This system shows an example in which a broadcast signal is unilaterally transmitted from a transmission side to a reception side. On the transmission side, a device in which a video camera 11, an electrical / optical converter 13, and an optical amplifier 14 are connected in this order is provided. The output signal of the optical amplifier 14 is output toward the optical fiber communication path P1. The optical fiber communication path P1 is selected from the existing optical fiber communication paths as already described, and satisfies a certain transmission characteristic standard. The optical fiber communication path P <b> 1 is managed by a communication carrier, and is allowed to transmit and receive a predetermined signal between the terminal 15 and the terminal 16.

  The optical amplifier A1 is connected to the terminal 16 of the optical fiber communication path P1. The optical amplifier A1 is composed of, for example, a Raman amplifier as described above. The output of the optical amplifier A1 is connected to the terminal 17 of the optical fiber communication path P2 selected for transmitting the broadcast signal in the next section. Another optical amplifier A2 is connected to the other terminal 18 of the optical fiber communication path P2. The output of the optical amplifier A2 is connected to the terminal 19 of the optical fiber communication path P3 selected for transmitting the broadcast signal in the last section.

  For example, if the optical fiber communication paths P1, P2, and P3 are each 50 kilometers to 100 kilometers long, broadcast signals are transmitted over a total distance of 150 kilometers to 300 kilometers. The terminal 20 of the optical fiber communication path P3 is connected to the receiving side equipment. The equipment on the receiving side includes an optical / electrical converter 25, a monitor television 27, a recording device 28, and the like.

  That is, in the above system, the image signal captured by the video camera 11 on the transmission side is an uncompressed serial digital signal, which is converted into an optical signal, and a sufficient gain is secured by the optical amplifier 14. , And sent to the optical fiber communication path P1. In order to compensate for transmission loss in the optical fiber communication paths P1, P2, and P3, an optical amplifier A1 is additionally inserted at the relay point of the optical fiber communication paths P1 and P2. That is, this is an additional amplifier that is not provided in the existing communication path. Similarly, an optical amplifier A2 is additionally inserted at the relay point between the optical fiber communication paths P2 and P3. As shown in the broken circle in FIG. 1, the optical dispersion compensator X1 can be combined with the optical amplifier A1 (the optical dispersion compensator X2 is combined with the optical amplifier A2) and inserted at the relay point. . By inserting the optical dispersion compensators X1 and X2 in this way, it is possible to secure a communication speed and signal quality capable of real-time transmission over a long distance by correcting optical signal waveform distortion in the optical fiber communication path.

  As described above, uncompressed digital broadcast signals are transmitted in real time from the transmission side to the reception side using the optical fiber communication channels P1, P2, and P3 borrowed from the communication carrier while maintaining a predetermined quality. be able to. This signal is converted into an electric signal on the receiving side and displayed on the monitor television 27. Recording can also be performed by the recording device 28. If the optical fiber communication paths P1, P2, and P3 are selected such that the transmission delay characteristic and the band characteristic satisfy a predetermined standard, the broadcast signal received on the receiving side is compared with the broadcast signal photographed by the video camera 11. The time delay is extremely small. Therefore, for example, video cameras 11 are arranged in various places, and images taken at these places are transmitted in real time to broadcast stations, and any of them receives and records broadcast signals with almost no time delay, or multi-way relay It becomes possible to broadcast.

  The above system is an example in which a broadcast signal is unilaterally transmitted from the transmission side to the reception side. However, the system of the present invention can be similarly applied to bidirectional communication. Furthermore, in a shooting site, a plurality of video cameras are generally arranged, and a request for simultaneously transmitting signals shot by these cameras is generally required. Conventionally, a photographed signal is compressed and multiplexed and transmitted in the form of an electrical signal, and the reception side separates the signal and expands it to supply it to a monitor television or the like. Therefore, a time delay for compression and multiplexing processing cannot be avoided. In the present invention, multiplexing is performed at the optical signal level, and a multiplexed broadcast signal without time delay can be transmitted.

FIG. 2 is a block diagram showing a specific example of a real-time broadcast system that enables multiplexed bidirectional broadcast signal transmission.
FIG. 2A is a block diagram of an input / output device on a transmission side and a reception side. Devices as shown in this figure can be arranged at both ends of the optical fiber communication path. In this example, the transmission / reception of a broadcast signal obtained by photographing with a video camera between two points is shown. Of course, a system in which video and audio are transmitted from one side and only audio is transmitted from the other side may be used.

  Although four video cameras 11 are illustrated as an example, ten or more video cameras can be provided. The output signals of these video cameras 11 are converted into optical signals by the electric / optical converter 13 respectively. The output signal of the electrical / optical converter 13 is introduced into one optical fiber in the multiplexer 31. There are various existing technologies for multiplexing at the level of electrical signals such as ATM, but none are suitable for real-time communication with extremely small transmission delay. In this system, multiplexing in the state of an optical signal enables multiplexing without time delay.

  The optical signal collected in one optical fiber is amplified by an optical amplifier A5 such as a Raman amplifier and sent to the optical fiber communication path P5. On the other hand, the broadcast signal of the other party transmitted in the reverse direction from the optical fiber communication path P5 is branched by the branching device 33 and sent to the branching filter 32. The demultiplexer 32 has a wavelength-dependent device such as a prism, for example, and has a function of separating the multiplexed optical signal for each channel. The optical / electrical converter 25 converts the optical signal of each channel into an electrical signal and outputs it to the monitor television 27. In this example, as many monitor televisions as the number of channels are prepared. However, the signal of the optical / electrical converter 25 may be output to a recording device other than the monitor television or other broadcasting equipment.

  As described above, a multi-channel broadcast signal is converted into an optical signal, and these optical signals are collected and sent to one optical amplifier and one optical fiber communication channel to multiplex an uncompressed digital broadcast signal. Can be sent. Further, the multiplexed broadcast signal output from the optical fiber communication path can be separated for each channel using the duplexer 32 and supplied to the monitor television.

  FIG. 2B is a block diagram of an optical amplifier unit inserted at a relay point of the optical fiber communication path. Optical fiber communication paths P6 and P7 are selected such that a certain transmission delay and a certain transmission band are guaranteed. Broadcasting signals are transmitted to these optical fiber communication paths, and optical amplifiers A6 and A7 are inserted in order to compensate the level. The optical amplifiers A6 and A7 are arranged on the input side, the output side, or both sides of the optical fiber communication paths P6 and P7 to be used. For example, as shown in this figure, two optical amplifiers A6 and A7 are inserted between one terminal 35 of the optical fiber communication path P6 and one terminal 36 of the optical fiber communication path P7. One optical amplifier A 6 has a function of amplifying an optical signal output from the terminal 35 and outputting the amplified signal toward the terminal 36. The other optical amplifier A 7 has a function of amplifying the optical signal output from the terminal 36 and outputting it to the terminal 35. By newly inserting such a pair of optical amplifiers at the relay point, it is possible to connect and combine a plurality of optical fiber communication paths for long-distance real-time broadcasting.

  The system of the present invention realizes real-time broadcasting by selecting one or a plurality of optical fiber communication paths corresponding to distances within 200 kilometers between two points and connecting them in order. Therefore, real-time broadcasting can be realized over a long distance by providing relay points at several locations and inserting amplifiers. If the length of the optical fiber communication path to be selected is selected to be too short, the number of optical amplifiers inserted is remarkably increased, and the signal transmission quality cannot be maintained as a whole. On the other hand, if the length of the optical fiber communication path to be selected is selected too long, the transmission signal will deteriorate significantly, and even if an optical amplifier is inserted, the quality of the broadcast signal cannot be maintained. For this reason, as already demonstrated, it is preferable to select each optical fiber communication path to a section of 200 kilometers or less. If the quality of the optical fiber communication path is remarkably improved and the performance of the optical amplifier is also improved, these section lengths can be made longer.

FIG. 3 is a block diagram showing an example in which two-way communication of broadcast signals is performed between two locations in Tokyo and Nagoya using the input / output device as described above.
As shown in the figure, a video camera 11, a multiplexing device 41, an optical amplifier A11, a branching device 33, a separation device 42, and a monitor television 27 are provided in Tokyo. In Nagoya, a video camera 11, a multiplexing device 43, an optical amplifier A18, a branching device 34, a separating device 44, and a monitor television 27 are provided. Multiplexers 41 and 43 are devices including the electrical / optical converter 13 and the multiplexer 31 described with reference to FIG. The separation devices 42 and 44 are devices including the duplexer 32 and the optical / electrical converter 25 described with reference to FIG.

  When bi-directional real-time broadcast signal transmission is performed between Tokyo and Nagoya with this system, the optical fiber communication path P1 in section A connecting Tokyo and Odawara and between Odawara and Shizuoka are connected in advance. The optical fiber communication path P2 in section B, the optical fiber communication path P3 in section C connecting Shizuoka and Hamamatsu, and the optical fiber communication path P4 in section D connecting Hamamatsu and Nagoya are selected. Each optical fiber communication path measures transmission characteristics in advance and selects one that satisfies the requirements. Relay points will be provided in places such as Odawara, Shizuoka, and Hamamatsu. Optical amplifiers A12 to A17 that amplify and output optical signals bidirectionally are inserted at the relay points.

  The input terminal 51 of the optical fiber communication path P11 is a terminal that is permitted to be used by a communication carrier in Tokyo. The terminal 52 is a terminal in Odawara that is allowed to be used by a communication carrier. Between the terminal 51 and the terminal 52 is a communication path of an optical fiber for which a certain transmission characteristic is guaranteed by a communication carrier. The terminal 52 of the optical fiber communication path P11 and the terminal 53 of the optical fiber communication path P12 are both in Odawara. Optical amplifiers A12 and A13 are added between these terminals to compensate for transmission characteristics. Similarly, optical amplifiers are inserted between the terminals 54 and 55 provided in Shizuoka and between the terminals 56 and 57 provided in Hamamatsu. By making such a selection, a long-distance real-time broadcast communication path is realized by combining the existing optical fiber communication paths P11, P12, P13, and P14.

  When the optical fiber communication path is selected as described above, the total value of the signal transmission delay between Tokyo and Nagoya is 0.002 seconds at the maximum, sufficiently satisfying the evaluation standard of 0.3 seconds or less. it can. That is, no stress is felt even if a two-way call is made in real time. In this example, the amplifiers provided at the relay points of Odawara, Shizuoka, and Hamamatsu are Raman amplifiers. As a result, digital broadcast signals with few transmission errors can be transmitted in real time from Tokyo to Nagoya. According to experiments, it was possible to transmit a digital high-definition uncompressed video signal (HD-SDI) at a transmission rate of 1.5 Gbps from Tokyo to Nagoya with a transmission delay of 0.002 seconds or less. It was also possible to multiplex 40 channels of digitally converted NTSC television signals for transmission. In the above example, Tokyo to Nagoya was divided into 4 sections. In all cases, the section length was 200 km or less.

  According to the measured data, in the optical multiplex transmission experiment of the digital high-definition uncompressed video signal (HD-SDI), the transmission distance of 70 km was transmitted in the wavelength band of 1310 nanometers, and the signal-to-noise ratio was 60 dB on the transmission side. The result was 40 dB on the receiving side. That is, when the existing optical fiber communication path was selected to be 70 kilometers, a result that the practical use was possible was obtained. Further, in the wavelength band of 1550 nanometers, when the signal-to-noise ratio was 65 dB or more on the transmission side and the section distance was 100 to 200 km, 55 dB was obtained on the reception side. Here, too, the result that the practical use was possible was obtained. In addition, even if it inserted only one relay amplifier between Tokyo and Nagoya, the same result as the above was obtained. In addition, when the same experiment was conducted between Tokyo and Osaka with each optical fiber communication path being approximately 200 kilometers and inserting a repeater amplifier at two locations, the transmission delay was 0.0027 seconds. A sufficiently satisfactory result was obtained.

  On the other hand, when a section distance of 250 km was selected in the wavelength band of 1550 nanometers, the signal-to-noise ratio was 65 decibels or more on the transmitting side, whereas the result was 50 decibels on the receiving side. However, when the pathological signal used in the stress test of the serial digital communication path is measured, if it exceeds 200 kilometers, it is not always sufficient because of the optical multiplexing and the light dispersion characteristics. It was found that the transmission characteristics could not be satisfied. Therefore, for existing optical fiber communication paths such as dark fibers, a distance range of about 200 kilometers is selected, and an optical amplifier and an optical dispersion compensator are newly connected and combined. It has been demonstrated that real-time broadcast transmission can be realized. By this method, the result that real-time broadcasting communication over a long distance of about several hundred kilometers to 1,000 kilometers is possible.

  In the present invention, an optical fiber communication path selected from existing communication paths is used as a passive circuit having a certain transmission characteristic. Transmission signal level compensation is performed by an optical amplifier inserted at one or both ends of the optical fiber communication path, and transmission signal dispersion compensation is also performed by an optical dispersion compensator inserted at one or both ends, so the existing communication path is used. Nevertheless, the user can freely optimize the broadcast quality as a whole. In addition, according to the present invention, even when bidirectional communication is performed, the time delay of sound and images can be suppressed to a level that is not a concern at all.

  In the method of the present invention, an optical fiber communication path that sequentially connects two points and an arbitrary number of relay points between the two points is selected from existing communication paths that connect the two points. There is no need to tie them straight. Each optical fiber communication path has a length of 200 km or less. It is the length of the communication path, not the linear distance. In addition, a digital pulse whose waveform distortion is less than an allowable value is selected. This is to prevent signal degradation due to digital signal transmission errors. The total of the optical signal transmission delay times between the two points is selected to be 0.3 seconds or less. This is for real-time transmission. An optical fiber communication path satisfying the above conditions is selected and connected in order while providing a relay point.

  A new optical amplifier or optical dispersion compensator that is not originally included in the optical fiber communication path is inserted between the terminals of two adjacent optical fiber communication paths at the relay point. Only an optical amplifier may be inserted. Only the optical dispersion compensator may be inserted. Both an optical amplifier and an optical dispersion compensator may be inserted. The optical amplifier compensates the level of the optical signal transmitted to the optical fiber communication path. The optical dispersion compensator corrects optical signal waveform distortion in the optical fiber communication path. When an optical signal that is an uncompressed digital broadcast signal and is converted into a serial bit stream is transmitted, a signal transmission error directly degrades the received image. Therefore, in the present invention, in order to minimize signal transmission errors, an optical amplifier and an optical dispersion compensator that are not prepared on the side of the communication provider providing the optical fiber communication path are additionally inserted.

  Thus, a broadcast signal is sent from one or both of the two points to the optical fiber communication path. This broadcast signal is an uncompressed digital broadcast signal, which is an optical signal converted into a serial bit stream. On the transmission side, the pixel value data groups necessary to reproduce the image captured and acquired by the camera are sent out as they are in the order of acquisition, and on the reception side, the pixel value data groups are received in the order of acquisition. Then, they are played back in that order. A control signal and other data may be freely inserted in the empty time portion between adjacent pixel value data. That is, in the present invention, the transmission delay times of all the pixel value data are equal and within 0.3 seconds. There is no temporal replacement, overtaking, or waiting for pixel value data. Neither encoding processing nor bucketing processing, nor error correction processing is performed. According to this method, since a complicated control circuit for buffering signals is not required, the configuration of the transceiver can be simplified. As described above, real-time bi-directional communication is possible with no awareness of signal time delay.

FIG. 4 is an explanatory diagram of the use of the system of the present invention.
For example, as shown to (a) of a figure, a broadcast signal is transmitted from concert hall H1 using two real-time broadcasting systems P15 and P16. The real-time broadcast system P15 sends a live broadcast image of the concert at the concert venue H1 to the hotel H2. The real-time broadcast system P16 sends a live broadcast image of the concert at the concert venue H1 to the hall H3. In the system (b), four remote concert venues are connected by relay stations M1, M2, M3, M4 and real-time broadcast systems P121, P22, P23. Performances at each concert venue are sent to other venues in real time, enabling joint concerts. In this case, it is necessary to distribute voice and images in many channels and transmit in real time, and a large transmission delay is not allowed. Such a concert is realized for the first time by the system of the present invention.

  In addition, the system of the present invention can be widely used for the broadcast of the general meeting of shareholders, the transmission of surgical images of hospitals, broadcast education, and the like. For example, an image of a medical site can be transmitted to a terminal device of a specialist doctor and an operation can be performed while receiving advice from the specialist doctor. Since no time delay is allowed for communication, the present invention can be used effectively. For example, a director in a broadcasting station can also be used for collecting broadcast materials and CM materials while giving instructions to a person in charge of photographing a TV camera installed at a remote place. It can also be used effectively for video conferences between participants scattered in remote locations.

It is a block diagram which shows the real-time broadcast system specific example of this invention. It is a block diagram which shows the specific example of the real-time broadcast system which enabled the multiplexing bidirectional | two-way broadcast signal transmission. It is a block diagram which shows the example which performed the bidirectional | two-way communication of the broadcast signal specifically between two places, Tokyo and Nagoya, using the above input / output devices. It is application explanatory drawing of the system of this invention.

Explanation of symbols

11 Video camera 13 Electrical / optical converter 14 Optical amplifier 15, 16, 17, 18.19, 20 Terminals P1, P2, P3 Optical fiber communication path A1, A2 Optical amplifier X1, X2 Optical dispersion compensator 25 Optical / electrical conversion 27 Monitor TV 28 Recording device

Claims (3)

A combination of multiple optical fiber communication paths that have already been installed for telephone communication or data communication and are allowed to send and receive signals between both terminals, connect two points, and exchange data over time or In order to transmit an optical signal converted into a serial bit stream without waiting and without encoding or packetizing,
A plurality of optical fibers connecting the two points and the arbitrary number of relay points between them in order, each having a transmission band capable of transmitting a digital image signal, each having a length of 200 km or less. Select the optical fiber communication path so that the total optical signal transmission delay time of the communication path satisfies the condition of 0.3 seconds or less,
It is for compensating the level of the optical signal transmitted to the optical fiber communication path between the terminals of the two adjacent optical fiber communication paths at the relay point, and is included in the optical fiber communication path New optical amplifier or a new optical dispersion compensator for correcting optical signal waveform distortion in the optical fiber communication path, which is not included in the optical fiber communication path. ,
An uncompressed digital broadcast signal from at least one of the two points, and sending the serial bit stream optical signal to the optical fiber communication path,
A real-time broadcast signal transmission method comprising: receiving at least one of the two points the optical signal that has passed through the optical fiber communication path and the relay point in order. The real-time broadcast signal transmission method according to claim 1,
From at least one of the two points, it is an uncompressed digital broadcast signal, and an optical signal of two or more wavelengths converted into a serial bit stream is asynchronously sent to the optical fiber communication path,
A real-time broadcast signal transmission method, wherein a Raman amplifier is used as the optical amplifier inserted at the relay point. In the real-time broadcast signal transmission method according to claim 1 or 2,
An uncompressed digital broadcast signal from both of the two points, which is an optical signal having two or more wavelengths converted into a serial bit stream, is asynchronously sent to the optical fiber communication path,
A method for transmitting a real-time broadcast signal, wherein the optical signal is sequentially transmitted through the optical fiber communication path and the relay point at both of the two points.

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