JP2005176193A - Optical reception terminal for subscriber with input switching function of ftth system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a state that a subscriber cannot receive a service until the service being recovered if a trouble occurs in a photo diode (PD) or a transmission line. <P>SOLUTION: An ONU comprises a photoelectric converting unit 1 for sending an optical signal of a FTTH system to a subscriber after converting to a RF signal, a FTTH signal transmission path 2 for transmitting the converted RF signal, an optical monitoring circuit 3 for outputting a switching signal at the time of detecting the trouble by monitoring the optical signal, an auxiliary signal transmission path 4 capable of transmitting an auxiliary RF signal to be acquired from the system except for the FTTH system, and a switcher 5 capable of switching the path between the auxiliary signal transmission path 4 and the FTTH signal transmission path 2. When a trouble occurs in an input signal, the switcher changes the path to the auxiliary transmission path 4 from the FTTH signal transmission path 2 based on the switching signal send from the optical monitoring circuit 3, and the auxiliary RF signal is to be transmitted to the subscriber through the auxiliary transmission path 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The optical receiver terminal for subscribers with an input switching function of the FTTH system of the present invention is used for the FTTH system of CATV.

  The current CATV optical communication system includes an HFC system. As shown in FIG. 4, the BS broadcast wave received by the CATV station 50 by the BS antenna 51 and the CS broadcast wave received by the CS antenna 52 are transmitted from the 64QAM head end (64QAM HE) to the optical transmitter via the CATV head end. The analog broadcast wave transmitted and received by the terrestrial antenna 53 is transmitted from the CATV head end to the optical transmitter 54, the optical signal transmitted from the optical transmitter 54 is received by the optical receiver 55, and then transmitted to the main line to be cascade-connected. The signal is branched and amplified by the branching amplifier 56 and transmitted by the branching unit 57 and supplied to each subscriber. Some subscribers receive a terrestrial antenna 58 or receive a signal from the difficult viewing prevention facility 59. In this figure, the subscriber's house is a detached house, but the subscriber's house may be an apartment house such as an apartment or an apartment.

  In recent years, an FTTH (Fiber To The Home) system has been studied as an optical communication system for CATV. As shown in FIG. 5, the CATV station or the FTTH provider optically transmits BS broadcast waves and CS broadcast waves received by the satellite broadcast receiving antennas 51 and 52 from the 64QAM head end (64QAM HE) through the CATV head end. The analog broadcast wave sent to the transmitter 54 and received by the terrestrial antenna 53 is sent from the CATV head end to the optical transmitter 54, and the optical signal sent out from the optical transmitter 54 is amplified by the optical fiber amplifier 60 to the optical transmission line. The signal is branched by the optical branching device 61 and sent to the optical receiving terminal (ONU) for the subscriber. The optical signal is converted into the RF signal by the ONU, and the television (via the set top box (STB) of the subscriber A TV) or directly on TV. In this case, there is a subscriber who installs the terrestrial antenna 58 and receives the terrestrial antenna 58 or receives from the difficult viewing prevention facility 59.

  The ONU is normally configured as shown in FIG. 6, and converts an optical signal received from the optical transmission path into an electrical signal (RF signal) by a photodiode (PD), and this RF signal is converted into an impedance conversion circuit 62. And sent to the STB and TV via the amplifier 63. Also, an abnormality in the RF signal immediately after the conversion (that is, an abnormality in the optical signal) is detected by the optical monitoring circuit 64, and an abnormality detection signal ( Alarm signal: ALM signal) is output, and an alarm device such as an LED or a buzzer is operated to notify the abnormality.

  In the FTTH system of FIG. 5, if a failure (disconnection, etc.) occurs in the optical transmission line during the operation of the FTTH service, the optical signal stops and the service stops. Also, if a failure occurs in the PD in the ONU, even if an optical signal is sent from an FTTH service provider, the service is stopped without the optical signal being converted into an electrical signal. When the service is stopped, the subscriber notifies the operator of the abnormality, and the operator who received the notification searches for the location and cause of the abnormality and repairs it. The subscriber cannot receive the service until the repair work is completed, and if a failure occurs in the PD, the service cannot be received until the ONU is replaced.

  In the present invention, in the FTTH system, when transmission of an optical signal or an RF signal is stopped due to optical signal stoppage or PD failure, a spare RF signal obtained from a signal source other than the FTTH service is automatically and immediately joined. To prevent the influence of the FTTH service stoppage.

  The optical receiver terminal for subscribers with input switching function of the first FTTH system of the present application, as shown in FIG. 1, converts the optical signal of the FTTH system into an electrical signal (RF signal) and sends it to the subscriber. Obtained from a conversion unit 1, an FTTH signal transmission line 2 that transmits the converted RF signal, an optical monitoring circuit 3 that monitors the optical signal and outputs a switching signal when an abnormality is detected, and a system other than the FTTH system A backup signal transmission path 4 capable of transmitting a spare RF signal; and a switch 5 capable of switching between the backup signal transmission path 4 and the FTTH signal transmission path 2. The switch 5 includes the optical monitoring circuit 3 is switched from the FTTH signal transmission path 2 to the backup signal transmission path 4 based on the switching signal sent from the line 3, and the backup RF signal from the backup signal transmission path 4 is transmitted to the subscriber.

  The optical receiver terminal for subscribers with an input switching function of the second FTTH system of the present application is an RF signal obtained by converting the optical signal of the FTTH system in the first optical receiver terminal for subscribers as shown in FIG. It is also possible to provide a detection circuit 6 for detecting the switching signal so that the switching signal is output from the optical monitoring circuit 3 based on the output from the detection circuit 6 when the RF signal is abnormal.

  The optical receiver terminal for subscribers with an input switching function of the third FTTH system of the present application is the same as the optical receiver terminal for subscribers of the first subscriber, as shown in FIG. The system path 2 and the optical monitoring circuit 3 are combined into a single casing as a transmission side device 7, and the switch 5 and the backup signal transmission path 4 are combined into a separate casing and the switching side device 8 as a switch. An input terminal 9 capable of inputting an FTTH RF signal to the side device 8, a spare signal input terminal 10, and a switching signal input terminal 11 are provided, and the RF output terminal 12 of the transmission side device 7 is connected to the RF signal input of the switching side device 8. It is also possible to connect / disconnect the switching signal output terminal 13 of the transmission side device 7 to / from the switching signal input terminal 11 of the switching side device 8 to / from the terminal 9.

  The optical receiver terminal for subscribers with input switching function of the fourth FTTH system of the present application is the optical receiver terminal for subscribers of the third subscriber, as shown in FIG. A detection circuit 6 for detecting an RF signal obtained by converting the signal is also provided, and a switching signal is output from the optical monitoring circuit 3 based on the output from the detection circuit 6 when the RF signal is abnormal.

  The optical receiver terminal for subscribers with an input switching function of the fifth FTTH system of the present application converts the optical signal of the FTTH system into an electrical signal (RF signal) and sends it to the subscriber as shown in FIG. A converter 1; an FTTH signal transmission path 2 for transmitting the converted RF signal; an optical monitoring circuit 3 for monitoring the optical signal and outputting an alarm signal when the optical signal is abnormal; and a detection circuit for the RF signal 6, an RF monitoring circuit 14 that outputs a switching signal when an abnormality of the RF signal is detected by the detection circuit 6, and a spare signal transmission path 4 that can transmit a spare RF signal obtained from a system other than the FTTH system The auxiliary signal transmission system 4 and the switch 5 capable of switching the FTTH signal transmission system 2 are provided, and the optical / electrical converter 1, the FTTH signal transmission system 2 and the optical monitoring circuit 3 are combined into one housing. To the transmitting device 7 The wave circuit 6, the RF monitoring circuit 14, the switching device 5, and the standby signal transmission path 4 are combined into a separate housing from the housing to form a switching device 8, and an input capable of inputting an FTTH RF signal to the switching device 8. A terminal 9 and a spare signal input terminal 10 are provided, and the RF output terminal 12 of the transmission side device 7 can be connected to and disconnected from the RF signal input terminal 9 of the switching side device 8.

  The optical receiver terminal for subscribers with an input switching function of the sixth FTTH system of the present application is the optical receiver terminal for subscribers with an input switching function of the FTTH system according to any one of the above, wherein the switch 5 is an optical signal or When the converted RF signal is recovered, the standby signal transmission line 4 is switched to the FTTH signal transmission line 2, and the RF signal of the FTTH system is transmitted to the subscriber.

  The optical receiver terminal (ONU) for subscribers with an input switching function of the FTTH system of the present invention has the following effects.

  In the first to sixth inventions, when an optical signal abnormality of the FTTH service occurs, the ONU switching circuit installed at the subscriber's house is automatically switched to the backup signal transmission line, and is normally installed in each home. Since the signal obtained from the existing antenna or the existing common hearing of CATV for radio wave interference is used as a spare RF signal, the same signal as the original signal of the FTTH service can be sent to the subscriber. In addition, the subscriber's wave is stopped only at the time of switching, and complete wave breakage can be prevented. If an alarm signal is output from the monitoring circuit and an LED or a buzzer is operated, an abnormality in the FTTH service can be automatically confirmed when an abnormality occurs, which is useful for subsequent repair work. Since the switching signal from the monitoring circuit can also be used as an alarm signal, the configuration of the ONU is simplified, and the size and cost of the ONU can be reduced.

  In the second invention, since the RF signal is monitored and the switching signal is output, the switching circuit is automatically switched to the spare signal transmission line even when the RF signal is abnormal, and is usually installed in each home. It is also possible to send the same signal as the original signal of the FTTH service to the subscriber by using a spare RF signal obtained from an antenna or an existing common hearing of CATV for radio wave interference. It is also possible to detect an abnormality in the RF circuit in the ONU.

  In the third and fourth inventions, the transmission side device and the switching side device are separated, the RF output terminal of the transmission side device is switched to the RF input terminal of the switching side device, and the switching signal output terminal of the transmission side device is switched. Since it is possible to connect / disconnect to / from the switching signal input terminal of the side device, if the subscriber has an existing optical receiver terminal (ONU) installed, the input switching function can be achieved simply by adding the switching side device. Therefore, the existing ONU can be used effectively, and the existing ONU is not wasted. Since the switching signal from the monitoring circuit can also be used as an alarm signal, the configuration of the ONU is simplified, and the size and cost of the ONU can be reduced.

  In the fifth aspect of the invention, the transmitting device is provided because the transmitting device and the switching device are separated and the RF output terminal of the transmitting device can be connected to and disconnected from the RF input terminal of the switching device. The subscriber only has to add a switching device, and there is no waste. In addition, since an RF monitoring circuit is provided in the switching device so that a switching signal is generated when the RF signal is abnormal, an abnormality in the optical signal and the RF circuit is detected even if the transmitting device does not have an optical monitoring circuit. By switching the switch, the same signal as the original signal of the FTTH service can be sent to the subscriber.

  In the sixth invention, when the abnormality of the optical signal of the FTTH service or the RF signal converted from the FTTH service is recovered, the ONU switching circuit installed in the subscriber's house automatically returns to the FTTH signal transmission line, The original signal of the FTTH service is sent to the subscriber.

(Embodiment 1)
A first embodiment of an optical receiver terminal (ONU) for a subscriber with an input switching function of an FTTH system of the present invention will be described with reference to FIG. FIG. 1 is used in place of the ONU of the FTTH system shown in FIG. 5. The existing ONU shown in FIG. 6 has a spare signal transmission path 4 capable of transmitting a spare RF signal, and an input side thereof. An input terminal 10 and a switch (RF switch) 5 are added on the output side. The spare signal transmission line 4 transmits a spare RF signal obtained from a system other than the FTTH system, for example, a spare RF signal obtained from the antenna 58 of each individual subscriber shown in FIG. Is to do.

  The ONU shown in FIG. 1 includes an optical / electrical converter (photodiode) PD that converts an optical signal transmitted from the FTTH system (each service provider) into an electrical signal (RF signal), and an impedance (usually 75Ω) of the CATV system. And an impedance conversion circuit 62 for matching the impedance (several KΩ) of the PD higher than that, and an amplifier 63 for amplifying the RF signal converted by the PD, which are connected to the FTTH signal transmission path 2. It is composed. Further, an optical monitoring circuit 3 is provided that detects an RF signal immediately after conversion obtained from the PD as a monitor voltage (current) and detects an abnormality such as the presence or level of the RF signal immediately after conversion, that is, an optical signal. A comparator is used in the optical monitoring circuit 3, and the RF signal immediately after conversion taken out for monitoring is compared with a preset reference value, and when an abnormality occurs, a switching signal that also serves as an alarm signal is output when an abnormality is detected And sent to the switch 5. The light monitoring circuit 3 is connected to an alarm device (not shown) such as an LED or a buzzer, which operates in response to an alarm signal to notify an abnormality. Further, in FIG. 1, the detection circuit 6 is connected to the output side of the amplifier 63, the RF signal output from the amplifier 63 is detected by the detection circuit 6, and the light monitoring circuit 3 also switches the alarm signal when an abnormality is detected. A signal is output. E in FIGS. 1 to 3 is a power source for driving the optical monitoring circuit 3.

  In the optical receiver terminal for subscribers with an input switching function of the FTTH system of FIG. 1, when a switching signal is output from the optical monitoring circuit 3 and sent to the switching device 5, the switching device 5 is connected to the FTTH signal transmission path up to that time. 2 is switched to the connection to the backup signal transmission line 4, and the RF signal sent to the backup signal transmission line 4 is output from the switch 5 and sent to the subscriber.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. This is an optical receiver terminal (ONU) for subscribers divided into two devices. The optical / electrical converter 1, the FTTH signal transmission line 2, the detection circuit 6, and the optical monitoring circuit 3 are provided. The switch 5 and the spare signal transmission path 4 are combined into a separate housing from the transmission device 7 as a switching device 8. An RF signal input terminal 9 for connecting the output terminal (RF output terminal) 12 of the FTTH signal transmission line 2 to the switching side device 8, a spare signal input terminal 10 for inputting a spare RF signal, An input terminal 11 for inputting a switching signal output from the monitoring circuit 3; an output terminal 12 of the FTTH signal transmission line at the RF signal input terminal 9; a spare antenna at the spare signal input terminal 10; Both devices 7 and 8 can be connected by connecting an RF signal source such as a hearing facility.

  In the ONU of FIG. 2, when the signal output from the optical monitoring circuit 3 is used as both a switching signal and an alarm signal and the signal output from the optical monitoring circuit 3 is sent to the switching unit 5, Is switched from the connection to the FTTH signal transmission line 2 to the connection to the spare signal transmission line 4, and the spare RF signal sent to the spare signal transmission line 4 is transmitted from the switch 5 to the subscriber. It is like that. Further, when there is an abnormality in the RF signal detected by the detection circuit 6, a switching signal and an alarm signal are output from the optical monitoring circuit 3, the switch 5 is switched, and the alarm is activated.

(Embodiment 3)
A third embodiment of the ONU of the present invention will be described with reference to FIG. This also divides the ONU into two parts. The optical / electrical converter 1, the FTTH signal transmission path 2, and the optical monitoring circuit 3 are combined into one housing as a transmission side device. The backup signal transmission line 4, the detection circuit 6, and the RF monitoring circuit 14 are combined into a separate housing from the transmission side device 7 to form the switching side device 8. The switching-side device 8 includes an RF signal input terminal 9 for inputting an FTTH RF signal and a spare signal input terminal 10 for inputting a spare RF signal. By connecting an output terminal 12 of the FTTH signal transmission line to the RF signal input terminal 9 and a spare RF signal source to the spare signal input terminal 10, both devices 7 and 8 can be connected. is there. By providing the detection circuit 6 and the RF monitoring circuit 14 in the switching-side device 8, it is possible to eliminate what corresponds to the switching signal input terminal 11 in FIG.

  In the ONU of FIG. 3, the RF monitoring circuit 14 is provided separately from the optical monitoring circuit 3, and when the switching signal output from the RF monitoring circuit 14 is sent to the switching device 5, the switching device 5 is connected to the previous FTTH signal transmission path. 2 is switched to the connection to the backup signal transmission system 4 and the RF signal sent through the backup signal transmission system 4 is output from the switch 5 and the backup RF signal is transmitted to the subscriber. It is made to do.

  In any of the ONUs of FIGS. 1 to 3, after the abnormality of the FTTH system is recovered and the optical signal or the RF signal becomes normal, the output of the switching signal from the optical monitoring circuit 3 or the RF monitoring circuit 14 is generated. It stops and the switch 5 automatically returns to the FTTH signal transmission line 2 so that the RF signal of FTTH is transmitted to the subscriber. Switching of the switch 5 after recovery from an abnormality can be performed manually.

  Since the switch 5 is provided with an RF signal input terminal 9, it is necessary to provide a power superimposition function for the switching side device 8 so that power can be supplied to the antenna (BS / CS / VHF / UHF) connected to the input terminal 10. There is. It is desirable to provide an ON / OFF switch so that the power supply can be cut off when the signal is drawn in by a coaxial cable of an existing common hearing facility or the like and power supply is not necessary.

Explanatory drawing which shows the 1st example of ONU of this invention. Explanatory drawing which shows the 2nd example of ONU of this invention. Explanatory drawing which shows the 3rd example of ONU of this invention. Explanatory drawing which shows an example of the FTTH system currently examined. Explanatory drawing which shows an example of the present HFC system and a difficult-to-view countermeasure facility. Explanatory drawing of the conventional ONU.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical / electrical conversion part 2 FTTH signal transmission system 3 Optical monitoring circuit 4 Backup signal transmission system 5 Switch 6 Detection circuit 7 Transmission side device 8 Switching side device 9 RF signal input terminal 10 Reserve signal input terminal 11 Switch signal input Terminal 12 RF output terminal 13 Switching signal output terminal 14 RF monitoring circuit

Claims (6)

  An optical / electrical converter (1) that converts an optical signal of the FTTH system into an electrical signal (RF signal) and sends it to a subscriber, an FTTH signal transmission system (2) that transmits the converted RF signal, and the optical signal An optical monitoring circuit (3) for monitoring a signal and outputting a switching signal when an abnormality is detected, a spare signal transmission path (4) capable of transmitting a spare RF signal obtained from a system other than the FTTH system, and spare signal transmission A switch (5) capable of switching between the system path (4) and the FTTH signal transmission system path (2), the switch (5) based on a switching signal sent from the optical monitoring circuit (3); The FTTH signal transmission line (2) is switched to the spare signal transmission line (4), and the spare RF signal from the spare signal transmission line (4) is transmitted to the subscriber. Optical receiver for subscribers with input switching function Vessel.   2. A subscriber optical receiver terminal with an input switching function for an FTTH system according to claim 1, further comprising a detector circuit (6) for detecting an RF signal obtained by converting an optical signal of the FTTH system, and a detector circuit when an RF signal is abnormal. An optical receiving terminal for subscribers with an input switching function of an FTTH system, wherein a switching signal is output from the optical monitoring circuit (3) based on the output from (6).   2. The optical receiver terminal for subscribers with an input switching function of the FTTH system according to claim 1, wherein the optical / electrical converter (1), the FTTH signal transmission line (2), and the optical monitoring circuit (3) are combined into one casing. Are collectively referred to as a transmission side device (7), and the switch (5) and the backup signal transmission line (4) are collectively combined with the above-mentioned housing as a switching side device (8), and the switching side device (8). Are provided with an input terminal (9) capable of inputting an RF signal of FTTH, a spare signal input terminal (10), and a switching signal input terminal (11), and switches the RF output terminal (12) of the transmission side device (7). The switching signal output terminal (13) of the transmission side device (7) can be connected to and disconnected from the switching signal input terminal (11) of the switching side device (8) to the RF signal input terminal (9) of the side device (8). FTTH system subscriber switching light with input switching function Shin terminal device.   In the optical receiver terminal for subscribers with an input switching function of the FTTH system according to claim 3, the transmitter device (7) is also provided with a detection circuit (6) for detecting an RF signal obtained by converting the optical signal of the FTTH system, An optical receiving terminal for a subscriber with an input switching function of an FTTH system, wherein a switching signal is output from an optical monitoring circuit (3) based on an output from a detection circuit (6) when an RF signal is abnormal.   An optical / electrical converter (1) that converts an optical signal of the FTTH system into an electrical signal (RF signal) and sends it to a subscriber, an FTTH signal transmission system (2) that transmits the converted RF signal, and the optical signal The optical monitoring circuit (3) for monitoring the signal and outputting an alarm signal when the optical signal is abnormal, the RF signal detection circuit (6), and the detection circuit (6) are switched when an abnormality of the RF signal is detected. An RF monitoring circuit (14) for outputting a signal, a spare signal transmission line (4) capable of transmitting a spare RF signal obtained from a system other than the FTTH system, a spare signal transmission line (4), and the FTTH signal A switch (5) capable of switching the transmission line (2), and the optical / electrical converter (1), the FTTH signal transmission line (2), and the optical monitoring circuit (3) are combined into one housing. Transmitting side equipment (7), detector circuit (6) and RF monitoring circuit 14), the switch (5), and the spare signal transmission line (4) can be combined into a separate housing from the housing to form a switching device (8), and an FTTH RF signal can be input to the switching device (8). Input terminal (9) and spare signal input terminal (10) are provided, and the RF output terminal (12) of the transmitting device (7) is connected to the RF signal input terminal (9) of the switching device (8). An optical receiving terminal for a subscriber with an input switching function of an FTTH system, characterized in that it can be detached.   6. The optical receiver terminal for subscribers with an input switching function of the FTTH system according to claim 1, wherein the switch (5) is a standby signal when the optical signal or an RF signal converted from the optical signal is recovered. An optical receiving terminal for a subscriber with an input switching function of an FTTH system, wherein the RF signal of the FTTH system is transmitted to the subscriber by switching from the transmission path (4) to the FTTH signal transmission path (2) vessel.

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