JP5000389B2 - Optical broadcast transmission system and optical terminal device - Google Patents

Description

  The present invention relates to an optical broadcast transmission system for transmitting television broadcasts, announcement broadcasts for notifying earthquakes, and the like, and an optical terminal device used in this system.

  2. Description of the Related Art Conventionally, some optical broadcast transmission systems transmit television broadcasts as well as audio announcement broadcasts when necessary. An example of an optical terminal device used in such an optical broadcast transmission system is disclosed in Patent Document 1.

  In the optical terminal device disclosed in Patent Document 1, a photoelectric conversion unit that converts an optical signal transmitted from the center device into an electrical signal is provided, and a television broadcast signal included in the electrical signal output by the photoelectric conversion unit is: Amplified by a high-frequency amplifier circuit for television broadcasting. When the electrical notification broadcast signal is included in the electrical signal, the speech notification broadcast signal is amplified by a high frequency amplification circuit for speech notification broadcast, and the output signals of both amplification circuits are combined and output.

JP 2006-174221 A

  Since the voice notification broadcast has a public purpose for notifying the occurrence of a disaster, for example, there is a demand to enable reception in all homes in the broadcast area of the optical transmission system. Therefore, the optical terminal device disclosed in Patent Document 1 may be installed in each home in the broadcast area. However, some homes do not want to receive television broadcasts. It is difficult to collect expenses from receiving television broadcasts from such homes, which can be used illegally. In order to prevent this, it is necessary to manufacture a dedicated optical terminal device for notification that receives only a voice notification, which increases the cost of the entire optical transmission system.

  An object of the present invention is to provide an optical terminal device capable of receiving notification broadcasts and capable of switching to enable or disable reception of a joint reception signal, and an optical transmission system using the optical terminal device.

An optical transmission system according to one embodiment of the present invention includes a center device and a plurality of optical terminal devices connected to the center device through an optical transmission path. The center device converts the joint reception signal and the notification signal, which are electrical signals, into optical signals and transmits them to the optical transmission line. As the joint reception signal, a television broadcast signal received by an antenna can be used, or an independent broadcast signal produced on the center device side can be used. As the notification signal, for example, a voice notification signal can be used. The plurality of optical terminal apparatuses restore the joint reception signal and the notification signal from the optical signal received from the optical transmission path and output the restored signal. The center apparatus simultaneously converts a control signal for controlling the output of a specific optical terminal apparatus into the optical signal and transmits the optical signal to the optical transmission line. Each optical terminal device, the optical signal to the electrical signal, and parasitic lightning photoelectric conversion means for converting at even parasitic power outage, the notification signal only extracted and in a power failure from said electrical signals the photoelectric conversion unit has converted a notification signal extraction means for outputting, said photoelectric conversion means extracts only the joint reception signal from the electrical signal converted, the joint reception signal processing means for amplifying the joint reception signal, the photoelectric conversion unit has converted The control signal is extracted from the electrical signal, and the output signal of the joint reception signal processing means is set to one of output and non-output according to the extracted control signal, or the joint reception signal processing means is operated and not operated. And control means for one of the operations.

Moreover, even if a power failure occurs, the announcement broadcast can be reliably received.

In an optical terminal device according to another aspect of the present invention, a joint reception signal, a notification signal, and a control signal for making the specific optical terminal device unviewable are transmitted from the center device via an optical transmission line. The photoelectric conversion means converts the optical signal obtained by converting the electrical signal including the above-mentioned electrical signal into the electrical signal without power supply even during a power failure. The notification signal extraction means extracts and outputs the notification signal from the electrical signal from the photoelectric conversion means even during a power failure. Only the joint reception signal is extracted from the electrical signal converted by the photoelectric conversion means, and the joint reception signal processing means processes the joint reception signal so that the joint reception signal can be viewed. For example, the joint reception signal processing means amplifies the joint reception signal. Alternatively, it is converted into an intermediate frequency signal and amplified. The control means extracts the control signal from the electrical signal converted by the photoelectric conversion means, and the control means outputs and does not output the output signal of the joint reception signal processing means according to the extracted control signal Or the joint reception signal processing means is one of operation and non-operation.

Even if a power failure occurs, the announcement broadcast can be reliably received.

  As described above, according to the present invention, the notification broadcast can be received in each home in the joint reception area, and the joint reception signal cannot be received in a home not desired. Can be done. In addition, the optical terminal device can reliably receive the notification signal even if a power failure occurs.

  The optical transmission system according to the first embodiment of the present invention has a center device 2 as shown in FIG. The center device 2 is provided with a high frequency head end portion (REHE portion) 4. The high frequency head end unit 4 outputs a joint reception signal, for example, a television broadcast signal received by an antenna (not shown). Television broadcast signals include those obtained by converting satellite broadcast signals or satellite communication signals into intermediate frequency signals in the 1 GHz band. Alternatively, in addition to the television broadcast signal, a self-broadcast signal produced by an operator of the joint reception system is also included in the joint reception signal. In addition, a voice notification signal is also output from the high-frequency head end unit 4. This is broadcast when a disaster such as an earthquake occurs, for example, and is an FM audio signal using a frequency band of 76 MHz to 90 MHz, for example.

  These television broadcast signals and audio notification signals are supplied to the optical transmission unit 6 where they are converted into optical signals and transmitted to an optical transmission path, for example, the optical fiber 8. The optical fiber 8 is wired to each home in the transmission area of this optical transmission system.

  In each household, an optical terminal device 10 is arranged, connected to the optical fiber 8, and receives the optical signal described above. The optical terminal apparatus restores the television broadcast signal and the audio notification signal from the optical signal, outputs the television broadcast signal to the output terminal 12 for a television receiver (not shown), and illustrates the audio notification signal. No output from the output terminal 14 for the voice notification receiving terminal device. These optical terminal apparatuses 10 are assigned different addresses in advance.

  The center apparatus 2 uses a digital signal including an address assigned to each optical terminal apparatus 10 that cannot output a television broadcast signal and a command instructing the above-described instruction to disable the carrier wave. A control signal transmission unit 15 for generating a control signal obtained by modulating the signal. This control signal may be plural or singular. The frequency of the carrier wave of the control signal is different from, for example, a television broadcast signal and a voice notification signal. The control signal is transmitted to the high-frequency head end unit 4, transmitted to the optical transmission unit 6 together with the television broadcast signal and the voice notification signal, converted into an optical signal, and transmitted to each optical terminal device 10 via the optical fiber 8. .

  The optical terminal device 10 has a photoelectric conversion unit 16 as shown in FIG. The photoelectric conversion unit 16 operates with no power supply, for example, as shown in FIG. That is, the optical signal is converted into a television broadcast signal, an audio notification signal, and a control signal without receiving supply of operating power.

The photoelectric conversion unit 16 includes a light receiving element, for example, a photodiode 18, and generates a current corresponding to the light amount between the anode and the cathode when receiving an optical signal. The anode and the cathode of the photodiode 18 are connected between a load, for example, a transformer, specifically, a primary winding 20 p of the high-frequency transformer 20. The primary winding 20p has an intermediate tap 20t, and the intermediate tap 20t is connected to a reference potential, for example, a ground potential. The anode of the photodiode 18 is connected to the ground potential via the high frequency blocking coil 22. As a result, the photodiode 18 is not grounded in terms of high frequency. One end of the secondary winding 20 s of the high-frequency transformer 20 is grounded, and the other end is connected to a television broadcast signal processing unit 26, an audio notification signal processing unit 28, and a control signal processing unit 30 described later via a capacitor 24. .

  In the photoelectric conversion unit 16, no bias is supplied to the photodiode 18, and the photodiode 18 is used in a biasless state. Therefore, the photoelectric conversion unit 16 can convert an optical signal even in the event of a power failure.

When the photodiode 18 receives an optical signal, a current flows through the primary winding 20p of the high-frequency transformer 20 in accordance with the amount of light, and a television broadcast signal, an audio notification signal, and a control signal are induced in the secondary winding 20s. It is supplied to each processing unit via a capacitor 24.

  The television broadcast signal processing unit 26 includes extraction means for extracting only the television broadcast signal from the input television broadcast signal, audio notification signal, and control signal, for example, a band pass filter, and amplifies the extracted television broadcast signal. And output. An open / close switch 32 is provided between the output side of the television broadcast signal processing unit 26 and the output terminal 12. The open / close switch 32 is normally closed and is opened when a command to be described later is given. When the open / close switch 32 is closed, a television broadcast signal is output to the output terminal 12, but when the open / close switch 32 is open, no television broadcast signal is output to the output terminal 12.

The voice notification signal processing unit 28 includes extraction means for extracting a voice notification signal from the input television broadcast signal, voice notification signal, and control signal, for example, a band pass filter, amplifies the extracted voice notification signal, and outputs it. Supply to terminal 14. Therefore, as long as the voice notification signal is transmitted from the center device 2, the voice notification signal is output to the output terminal 14 of any optical terminal device 10.

The control signal processing unit 30 includes extraction means for extracting a control signal from the input television broadcast signal, audio notification signal, and control signal, for example, a band-pass filter, and the extracted control signal is digitally amplified after being amplified. The signal is demodulated and supplied to the control means, for example, the CPU 34. The CPU 34 stores an address assigned to the optical terminal device 10 in which the CPU 34 is provided, and determines whether the address included in the digital signal matches the assigned address. If they match, it is determined whether or not the instruction included in the digital signal indicates that television broadcast output is impossible. In the case of instructing that output is impossible, the CPU 34 opens the open / close switch 32. As a result, the television broadcast signal is not output to the output terminal 12. If the output is not instructed, the open / close switch 32 remains closed, and a television broadcast signal is output to the output terminal 12.

  Since it is configured in this manner, it is possible to prevent the television broadcast signal from being output by a desired one of the optical terminal devices 10. However, the voice notification signal is output in any optical terminal device. In addition, since the photoelectric conversion unit 16 operates with no power source, the voice notification signal is output from the photoelectric conversion unit 16 even when a power failure occurs. The voice notification signal processing unit 28 includes a through circuit that allows the output terminal 14 to pass through the voice notification signal supplied to the input side when a power failure occurs.

  The optical terminal device 10a of the optical transmission system according to the second embodiment of the present invention has a television broadcast signal, a voice notification signal, and a control signal extracted from the photoelectric conversion unit 16 as a voice notification signal processing unit as shown in FIG. The voice notification signal is extracted by the extraction means, for example, the band pass filter 40. That is, the amplification unit is not provided. The television broadcast signal, audio notification signal, and control signal from the photoelectric conversion unit 16 are supplied to a television broadcast signal amplifying unit 44 as a television broadcast signal processing unit via a branching unit 42, where the television broadcast signal is transmitted. Are extracted and amplified. The amplified television broadcast signal is supplied to the output terminal 12 via the one branching unit 46. The television broadcast signal branched by the one branching unit 46 and the audio notification signal from the bandpass filter 40 are combined by the combiner 48 and supplied to the output terminal 14a.

  The television broadcast signal, the audio notification signal, and the control signal branched by the one branching unit 42 are converted into digital signals by the control signal receiving unit 30 and supplied to the CPU 34. When the address included in the digital signal is the address of the optical terminal device 10a and the CPU 34 instructs the television broadcast signal amplification unit 44 to operate, the CPU 34 energizes the television broadcast signal amplification unit 44. When a signal is supplied and an instruction to deactivate the television broadcast signal amplifying unit 44 is given, the deactivation signal is supplied to the television broadcast signal amplifying unit 44. For example, when the energizing signal is supplied, the operating power is supplied to the television broadcast signal amplifier 44, and when the deactivating signal is supplied, the operating power is not supplied.

  Therefore, when the instruction to inactivate the television broadcast signal amplifier 44 is given by the control signal, the television broadcast signal is not output to any of the output terminals 12 and 14a, but the television broadcast signal is amplified by the control signal. When an instruction to operate the unit 44 is given, a television broadcast signal is output from any of the output terminals 12 and 14a. When a voice notification signal is output from the output terminal 14a regardless of what instruction is given from the center apparatus 2, it is output. Even if a power failure has occurred, the photoelectric conversion unit 16 operates without power supply, so that a voice notification signal is output.

  As shown in FIG. 5, the optical terminal device 10b of the optical transmission system according to the third embodiment, in the second embodiment, the output signal of the bandpass filter 40 and the output signal of the television broadcast signal amplifying unit 44 Is supplied to selection means, for example, the high frequency relay 50, and one of the output signal of the bandpass filter 40 and the output signal of the television broadcast signal amplifying unit 44 is supplied to the output terminal 12a. The high frequency relay 44 operates so as to supply the output signal of the television broadcast signal amplifying unit 44 to the output terminal 12a at the normal time, and supplies the output signal of the band pass filter 40 to the output terminal 12a at the time of power failure.

  Therefore, when the center apparatus 2 instructs to operate the television broadcast signal amplifying unit 44, the television broadcast signal is normally output from the output terminal 12a and the television broadcast signal amplifying unit 44 is output from the center apparatus 2. When it is instructed not to operate, the television broadcast signal is not output from the output terminal 12a in normal times.

  On the other hand, when a power failure occurs, the output signal of the bandpass filter 40 is supplied to the output terminal 12a regardless of whether the center device 2 gives an instruction to operate or not operate the television broadcast signal amplifier 44. Therefore, a voice notification signal is output to the output terminal 12a.

  In the first embodiment, the output signal of the television broadcast signal processing unit 26 is not supplied to the output terminal 12 by the open / close switch 32 provided on the output side of the television broadcast signal processing unit 26. The switch 32 is provided between the power supply terminal of the television broadcast signal processing unit 26 and the operating power supply, and opening the switch 32 brings the television broadcast signal processing unit 26 into a non-operating state so that the output of the television broadcast signal processing unit 26 is output. It is also possible to prevent the signal from being supplied to the output terminal 12. In the first embodiment, the open / close switch 32 is opened when the control signal is supplied, and the control signal is supplied to the optical terminal device 10 that does not output the television broadcast signal. However, the open / close switch 32 is controlled. As a type that is closed when a signal is supplied, a control signal may be supplied to the optical terminal device 10 that outputs a television broadcast signal. In the first embodiment, the voice notification signal processing unit 28 amplifies the voice notification signal. However, the present invention is not limited to this. For example, the voice notification signal is frequency-converted into an appropriate intermediate frequency signal. The output signal may be amplified and output, or the audio signal demodulated from the intermediate frequency signal may be output.

1 is a block diagram of an optical transmission system according to a first embodiment of the present invention. It is a block diagram of the optical terminal device used in the optical transmission system of FIG. It is a block diagram of the photoelectric conversion part used for the optical terminal device of FIG. It is a block diagram of the optical terminal device of the optical transmission system of the 2nd Embodiment of this invention. It is a block diagram of the optical terminal device of the optical transmission system of the 3rd Embodiment of this invention.

Explanation of symbols

2 Center unit 8 Optical fiber (optical transmission line)
10 Optical terminal equipment

Claims (2)

A center device that converts the joint reception signal and the notification signal, which are electrical signals, into an optical signal and transmits the optical signal to the optical transmission line;
A plurality of optical terminal devices for restoring and outputting the joint reception signal and the notification signal from the optical signal received from the optical transmission path,
The center apparatus converts the control signal for not outputting a joint reception signal of a specific one of the optical terminal apparatuses into the optical signal, and transmits the optical signal to the optical transmission line.
The optical terminal device
Photoelectric conversion means for converting the optical signal into the electrical signal without power supply even in the event of a power failure;
Notification signal extraction means for extracting and outputting only the notification signal from the electrical signal converted by the photoelectric conversion means even during a power failure;
Joint reception signal processing means for extracting only the joint reception signal from the electrical signal converted by the photoelectric conversion means and amplifying the joint reception signal;
The control signal is extracted from the electrical signal converted by the photoelectric conversion means, and the output signal of the joint reception signal processing means is set to one of output and non-output according to the extracted control signal, or the joint reception Control means for causing the signal processing means to operate or not operate;
Optical broadcast transmission system provided. An optical signal converted from an electrical signal transmitted from the center device through an optical transmission line and including a joint reception signal, a notification signal, and a control signal for the center device to make a specific optical terminal device unviewable. Photoelectric conversion means that converts the signal to power even without power supply,
Notification signal extraction means for extracting and outputting only the notification signal from the electrical signal from the photoelectric conversion means, even during a power failure,
Joint reception signal processing means for extracting only the joint reception signal from the electrical signal converted by the photoelectric conversion means and processing the joint reception signal so as to be viewable;
The control signal is extracted from the electrical signal converted by the photoelectric conversion means, and according to the extracted control signal, the output signal of the joint reception signal processing means is one of output and non-output, or the Control means for operating or not operating the joint reception signal processing means;
Optical terminal device provided.

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