JP2010004159A - Broadcasting transmitter system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a broadcasting transmitter system improving reliability and maintainability and allowing easy selection of transmitting condition. <P>SOLUTION: The broadcasting transmitter includes a communication portion 16 and one monitoring portion 7. The communication portion 16 is composed of a modulator 161 and a communication antenna 162. The modulator 161 has a branch path 111 between an amplifier 13 and an optoelectric transducer 11 and modulates a broadcasting signal outputted to a branched destination. The communication antenna 162 emits the modulated output from the modulator 161 as a radio wave. The monitoring portion 7 is composed of a signal processing portion 15 for determining the quality of the broadcasting signal transmitted from the communication antenna 162. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a broadcast transmission apparatus system that improves reliability and maintainability and facilitates selection of transmission conditions.

  When transmitting broadcast signals, broadcast signal radio waves may be sent directly from the broadcast station, but when broadcasting signals are transmitted by optical fiber from the broadcast station to the radio tower or relay station, or to the receiver's house. There is. Compared to using a metal conductor cable such as a coaxial cable, this has advantages such as low loss and suitable for long-distance transmission, narrow diameter and easy installation, and wide transmission bandwidth. Because.

  As for broadcast signal distribution using optical transmission, for example, as in the optical CATV system of Patent Document 1, a star-type distribution is performed in parallel from a CATV center or a communication center provided between the center and a subscriber terminal to the subscriber terminal. May be delivered.

  For optical transmission between a broadcasting station and a transmission facility, for example, as described in Patent Document 2, on the premise of single-frequency relaying of digital terrestrial broadcasting, optical transmission is used to reduce wraparound interference during relaying. It is shown. At this time, serial type optical transmission is used.

JP-A-4-156516 JP 2004-289405 A

  In a distribution configuration such as that used in an optical CATV system, it is necessary to provide a uniform service toward a large number of reception points, so a star type in which a plurality of optical fibers are laid in parallel from the transmission side is used. . The star type has the advantage that there is no influence on other than the corresponding transmission line when a malfunction such as a failure occurs. However, a large number of optical fibers are laid directly from the transmission side, making the installation and configuration complicated. Become. On the other hand, in a configuration using serial type optical transmission for a broadcast transmission / reception apparatus, distribution is performed using a plurality of branches in the same system, so when a failure occurs, there is a possibility that the influence may be increased depending on the failure location. . For example, when the transmitting optical fiber is broken, no signal is transmitted to the system after the broken portion. Therefore, in addition to increasing the reliability by multiplexing the optical fibers, it is required to quickly identify and repair the failure location and to minimize the period and range in which transmission is not possible.

  Also, in a broadcasting system such as ISDB-T (Integrated Service Digital Broadcasting System for Terrestrial), transmission control information (for example, an emergency warning broadcasting start flag described in the STD-B31 standard of the Radio Industry Association of Japan) is included in a broadcast signal. If the transmission apparatus can determine these, transmission conditions can be selected more appropriately.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a broadcast transmission apparatus system that solves the above-described problems, is a simple serial transmission system, and has improved reliability and maintainability.

  In order to achieve the above object, an invention according to claim 1 is directed to an optical transmitter that converts a broadcast signal into an optical signal and transmits the optical signal, an optical fiber connected to the optical transmitter, and an optical signal from the optical fiber. Broadcasting comprising a photoelectric converter for converting into an electrical signal, an amplifier for amplifying the electrical signal from the photoelectric converter, and a broadcast signal output antenna for radiating the amplified electrical signal from the amplifier as a radio wave In a broadcast transmission apparatus system including a plurality of transmission apparatuses, the broadcast transmission apparatus has a branch path between the amplifier and the photoelectric converter, and modulates a broadcast signal output to a branch destination And a communication unit including a communication antenna that radiates the modulated output from the modulation unit as a radio wave, and a monitoring unit including a signal processing unit that determines the quality of the broadcast signal transmitted from the communication antenna. Parts is a broadcast transmission system, characterized by having one.

  According to a second aspect of the present invention, in the broadcast transmission apparatus system according to the first aspect, the signal processing unit selects a desired broadcast signal from the broadcast signals transmitted from the communication antenna; Results of comparing the output of the broadcast signal demodulation unit that demodulates the signal from the channel selection unit, the signal quality detection unit that detects the quality of the signal demodulated in the broadcast signal demodulation unit, and the reference value It is a broadcast transmitter system characterized by comprising a comparison / determination unit that outputs.

  According to a third aspect of the present invention, the signal quality detection unit measures a signal level-to-noise level ratio within a broadcast channel band, or calculates a data error rate (bit rate error) of a digital broadcast signal used for the broadcast signal. 3. The broadcast transmission apparatus system according to claim 1, wherein measurement is performed.

  In the broadcast transmission apparatus system of the present invention, the optical fiber network after the optical transmission apparatus is a serial type. As a result, a multi-drop method is realized that includes optical fibers 3 and 3a serving as trunk lines and optical fibers branched from the trunk fibers 3 and 3a. For this reason, the broadcast transmission apparatus system of the present invention can be simplified in configuration as compared with the star type. In addition, the broadcast transmission apparatus system of the present invention has a function of evaluating signal quality after branching, so that the monitoring unit can grasp the signal quality on each branch path in a lump. As a result, when a failure occurs, the range where the failure location exists can be specified, and level distribution to each branch path can be adaptively controlled.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a broadcast transmitting apparatus system 101 according to an embodiment of the present invention. The broadcast transmission apparatus system 101 includes a digital broadcast signal source 1, an optical transmission apparatus 100 having an electro-optical converter (E / O) 2 that converts an electrical signal into an optical signal, an optical fiber 3, optical branches 4, 5, and termination. Unit 6, monitoring unit 7, photoelectric converters (O / E) 11 and 21 for converting optical signals into electrical signals, filters 12 and 22, amplifiers 13 and 23, broadcast signal output antennas 14 and 24, signal processing unit 15 and communication units 16 and 26 are provided.

  In FIG. 1, the broadcast transmission apparatus system 101 branches and distributes to a first transmission apparatus (also referred to as a first branch path or branch line) 102 using the optical branch 4, and the nth (nth; n indicates a branch distribution to a transmission device 103 (also referred to as an nth branch path or branch line). The second to (n-1) -th transmitters are not shown. After the optical branch 5 which is the final branch, the end of the optical fiber 3 is housed in the termination box 6.

  FIG. 2A is a block diagram showing details of the signal processing unit 15 provided in the monitoring unit 7 of the broadcast transmitting apparatus system 101, and FIG. 2B is a communication unit 16 (26 according to the first embodiment). FIG.

  More specifically, the broadcast transmission apparatus system 101 includes an optical transmission apparatus 100 that converts a broadcast signal into an optical signal by the electro-optical converter 2 and transmits the optical signal, and an optical fiber 3 to which the optical signal from the optical transmission apparatus 100 is input. , Photoelectric converters 11 and 21 that convert optical signals from the optical fiber 3 into electrical signals, amplifiers 13 and 23 that amplify electrical signals from the photoelectric converters 11 and 21, and outputs from the amplifiers 13 and 23 Broadcast signal output antennas 14 and 24 for radiating the electrical signals as radio waves.

  In the first embodiment, the broadcast transmitting apparatus system 101 includes branch paths 111 and 112 provided between the amplifiers 13 and 23 and the photoelectric converters 11 and 21. In addition, as shown in FIG. 2B, the broadcast transmission apparatus system 101 modulates the broadcast signal output to the branch destinations of the branch paths 111 and 112, and is modulated from the modulation unit 161. Communication units 16 and 26 having communication antennas 162 that radiate broadcast signals as radio waves. Furthermore, the broadcast transmission apparatus system 101 includes a monitoring unit 7 that monitors broadcast signals from the communication units 16 and 26.

  The monitoring unit 7 includes a signal processing unit 15. As shown in FIG. 2A, the signal processing unit 15 selects a desired broadcast signal from the broadcast signals radiated from the communication antenna 162, and receives a signal from the channel selection unit 151. The broadcast signal demodulator 152 to be demodulated, the signal quality detector 153 to detect the quality of the signal demodulated by the broadcast signal demodulator 152, and the comparison that outputs the result of comparing the output of the signal quality detector 153 and the reference value And a determination unit 154.

  Hereinafter, the operation of the broadcast transmitting apparatus system 101 will be described.

  A broadcast signal from the digital broadcast signal source 1 is converted into an optical signal by the electro-optical converter 2 and transmitted through the optical fiber 3. In this case, the distribution is not distributed in a separate optical fiber for each transmission system, but a so-called star-type configuration, in which the optical fiber 3 (main line fiber) is branched and distributed to each branch path using the optical branches 4 and 5 ( Here, a multi-drop type) is used.

  The optical signal branched by the optical branch 4 in the first transmission device 102 is converted into an electrical signal by the photoelectric converter 11. The electric signal is reduced in noise and interference signals outside the desired band by the filter 12, amplified to a desired signal level by the amplifier 13, and broadcast electric waves from the broadcast signal output antenna 14 toward the service area (receivable range). Is emitted as.

  Similarly, also in the n-th transmitter 103, the optical signal branched by the optical branch 5 is converted into an electrical signal by the photoelectric converter 21. The electric signal is radiated as a broadcast radio wave through the filter 22, the amplifier 23, and the broadcast signal output antenna 24.

  As described above, the multi-drop type has an effect that the optical fiber can be easily laid and the configuration can be simplified because the optical signal can be distributed from the same system by a plurality of branches as compared to the star type.

  The number of branches n can be arbitrarily selected according to the desired number of transmitters, but is represented by the required input signal level of the receiver and the signal quality at the reception point (for example, the ratio of the signal level to the noise or interference signal level) (For example, if the broadcasting is ISDB-T, it is detailed in the standard STD-B21 of the Japan Radio Industry Association).

  The noise level of the signal output from the digital broadcasting signal source 1 is added to the noise increase in the electro-optic converter 2, the noise increase in the opto-electric converter 11, and the noise increase in the amplifier 13. The noise level is obtained. Also, with respect to the signal level of the signal output from the digital broadcast signal source 1, the optical output level at the electro-optical converter 2, the transmission loss at the optical fiber 3, the attenuation due to the branch loss at the optical branch 4, and the light The output signal level of the electrical converter 11, the attenuation at the filter 12, the amplification factor of the amplifier 13, the antenna gain of the broadcast signal output antenna 14, the spatial propagation loss due to the longest distance of the service area, and the influence of reflection in spatial propagation Add the minutes to get the overall signal level. The signal level at the reception point and the ratio between the signal level and the noise level must satisfy the receiver required input signal quality defined in the standard (STD-B21 etc.).

  On the other hand, in the conventional multi-drop type, distribution is performed using a plurality of branches in the same system, so that when a failure occurs, the influence may be increased depending on the failure location. For example, when a trunk optical fiber is damaged, no signal is transmitted to the system after the damaged portion. Therefore, conventionally, it is required to multiplex the trunk line system and to minimize the period and the range in which the repair of the failed part cannot be transmitted quickly.

  Therefore, in the present invention, the broadcast signal is branched from the output of the filter 12 by the branch path 111, and the branched broadcast signal is wirelessly transmitted from the communication unit 16 to the monitoring unit 7. The branched broadcast signal may be transmitted from the communication unit 16 to the monitoring unit 7 by wire.

  As shown in FIG. 2A, the signal processing unit 15 includes a channel selection unit 151, a broadcast signal demodulation unit 152, a signal quality detection unit 153, and a comparison determination unit 154. A desired broadcast channel is selected by the channel selection unit 151 from the broadcast signal branched from the output of the filter 12 by the branch path 111, the output is demodulated by the broadcast signal demodulation unit 152, and the signal level versus noise is determined from the demodulated signal. Signal quality such as level ratio (S / N ratio) or data error rate in digital broadcasting is detected by a signal quality detection unit 153 and compared with a reference value by a comparison / determination unit 154. Here, the reference value is a value set so as to satisfy the receiver required input signal quality defined in the standard. With this configuration, the monitoring unit 7 can collectively grasp the S / N ratio, signal quality, and the like transmitted from the transmission apparatuses 102 and 103.

  1 and 2, the signal quality at the transmission point (each branch path) can be detected and compared with the reference value, and all the branch paths can be detected by the monitoring unit 7. Since there is an abnormality, it is possible to specify the range where the abnormality exists by looking at the situation of all the branch paths. For example, if there is an abnormality in the second branch path, the first branch path is normal, and if the third branch path is abnormal, between the first branch path and the second branch path (that is, It can be seen that an abnormality has occurred in the optical fiber 3) which is a trunk line. If both the first branch path and the third branch path are normal, it can be seen that an abnormality has occurred in the second branch path.

  Furthermore, since broadcast quality at the transmission points (each branch path) of each transmission device 102, 103 is centrally detected and determined by the signal processing unit 15 provided in the monitoring unit 7, the broadcast transmission device system 101 is simplified. can do.

  FIG. 3 is a block diagram specifically showing the configuration of a broadcast transmission apparatus system 301 according to another embodiment of the present invention. The broadcast transmitting apparatus system 301 includes a receiving antenna 8, an amplifier 9, and a filter 10 in place of the digital broadcast signal source 1 of the broadcast transmitting apparatus system 101 in FIG. 1, and the others are the same as the broadcast transmitting apparatus system 101 in FIG. It is.

  The present embodiment is a relay transmission system that receives a broadcast signal with a receiving antenna 8 installed in the air, and radiates it by radio waves from the broadcast signal output antenna 14 and the broadcast signal output antenna 24 again by raising the signal level. The separately transmitted broadcast signal is received by the receiving antenna 8, amplified to a desired signal level by the amplifier 9, noise and interference signals outside the desired band are reduced by the filter 10, and the optical transmitting apparatus 100 having the electro-optic converter 2. To enter.

  The path after the electro-optical converter 2 is the same as the configuration of FIGS. In the present embodiment, the noise of the amplifier 9 and the noise of the electro-optic converter 2 are added to the noise level of the signal received by the receiving antenna 8 to determine the total noise level. Further, the antenna gain of the receiving antenna 8, the amplification factor of the amplifier 9, the transmission loss of the optical fiber 3, and the like are added to the signal level of the signal received by the receiving antenna 8, and the total signal level is determined. From the total noise level and the total signal level, the total signal quality of the relay transmission system of this embodiment can be obtained. With regard to the broadcast signal relay facility, the ratio of the signal level to the noise level by the previous transmission device cannot be exceeded, and the ratio of the signal level to the noise level deteriorates every time relaying is repeated. The standard regarding multi-stage connection is described in, for example, the Japan Radio Industry Association Standard STD-B31.

  In conventional multi-stage relaying by radio, the propagation loss in space is large, so that signal quality is greatly deteriorated. On the other hand, in the relay device using the optical fiber 3 as in the present embodiment, since the transmission loss is small, the transmission level of the relay source may be small, and in a place where a radio wave is difficult to propagate such as a mountain area. Has the advantage of being able to transmit relatively long distances. In addition, similar to the embodiment shown in FIGS. 1 and 2, the system is simple in series, and the signal quality can be monitored through a branched path, so that there is an effect that the range in which a failure point exists can be specified. .

  In the present embodiment, a configuration is also possible in which a plurality of receiving antennas 8 and amplifiers 9 are provided, and an optimal receiving path is selected while monitoring signal quality. In this configuration, since a reception point with better signal quality can be selected, there is an effect that the quality of the relayed signal can be maximized.

  As described above, according to the present invention, the optical fiber network after the optical transmission device 100 becomes a serial type, and a multi-drop system configured by an optical fiber serving as a trunk line and an optical fiber branched from the trunk fiber is realized. For this reason, a structure can be simplified compared with a star type. According to the present invention, since the function of evaluating the signal quality after branching is provided, the signal quality at each branch is detected in the monitoring unit 7, the range where the fault exists is identified at the time of failure, and the system level Distribution (broadcast signal transmission path, etc.) can be adaptively controlled.

  The present invention is effective for a case where a signal is distributed from a central transmitting station in order to perform broadcasting in a limited area to an underground mall where a broadcast radio wave does not reach or a specific area, for example, when used in a broadcast relay device.

It is a block diagram of a broadcast transmitting apparatus system showing an embodiment of the present invention. (A) is a block diagram of a signal processing unit used for a monitoring unit of the broadcast transmission apparatus system of FIG. 1, and (b) is a block diagram of a communication unit. It is a block diagram of the broadcast transmission apparatus system which shows other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital broadcast signal source 2 Electro-optic converter 3 Optical fiber 4,5 Optical branch 6 Termination part 7 Monitoring part 8 Receiving antenna 9 Amplifier 10 Filter 11, 17, 21 Photoelectric converter 12, 22 Filter 13, 23 Amplifier 14 , 24 Broadcast signal output antenna 15 Signal processing unit 16, 26 Communication unit 100 Optical transmission device 101, 301 Broadcast transmission device system 102 First transmission device (first branch path)
103 nth transmitter (nth branch path)
111, 112 Branch path 151 Channel selection unit 152 Broadcast signal demodulation unit 153 Signal quality detection unit 154 Comparison determination unit 161 Modulation unit 162 Communication antenna

Claims (3)

An optical transmitter that converts a broadcast signal into an optical signal and transmits the optical signal;
An optical fiber connected to the optical transmitter;
A photoelectric converter for converting an optical signal from the optical fiber into an electrical signal;
An amplifier for amplifying an electrical signal from the photoelectric converter;
In a broadcast transmitter system comprising a plurality of broadcast transmitters having a broadcast signal output antenna that radiates the amplified electrical signal from the amplifier as a radio wave,
The broadcast transmission device has a branch path between the amplifier and the photoelectric converter,
A communication unit including a modulation unit that modulates a broadcast signal output to a branch destination and a communication antenna that radiates the modulated output from the modulation unit as a radio wave;
A broadcast transmitting apparatus system comprising one monitoring unit including a signal processing unit that determines the quality of the broadcast signal transmitted from the communication antenna. The broadcast transmission apparatus system according to claim 1, wherein the signal processing unit selects a desired broadcast signal from the broadcast signals transmitted from the communication antenna;
A broadcast signal demodulation unit that demodulates a signal from the channel selection unit;
A signal quality detection unit for detecting the quality of the signal demodulated in the broadcast signal demodulation unit;
A broadcast transmitting apparatus system comprising: a comparison / determination unit that outputs a result of comparing the output of the signal quality detection unit and a reference value.   The signal quality detection unit measures a signal level to noise level ratio in a broadcast channel band or measures a data error rate (bit rate error) of a digital broadcast signal used for the broadcast signal. The broadcast transmission apparatus system according to claim 1 or 2.

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