JP4128705B2 - Line monitoring system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a line monitoring system in an extended transmission system for extending subscriber line transmission to a remote subscriber.
[0002]
[Related background]
Conventionally, this type of extended transmission method is used for metallic subscriber line transmission of an ISDN basic interface (including a basic interface for PHS) as shown in FIG. In this extension transmission system, for example, an extension transmission path 30 such as an optical fiber cable is used to extend the transmission path, and a center station 1 having an exchange 11 and a remote subscriber home 2 having a terminal device (TE) 23. Are connected by a metallic subscriber line, and signal transmission by an echo canceller system is enabled.
[0003]
In this extended transmission system, the subscriber transmission lines 13 and 24 including the metallic subscriber transmission line are connected between the exchange 11 and the monitoring device 12 of the center station 1, and the monitoring device 21 and the network terminal (NT) 22 of the subscriber home 2. It is configured to provide at least two points between them. Further, in the extension transmission line 30 or the subscriber transmission line 24, the line quality is lower than a predetermined value, the signal synchronization is lost, the no signal is received, or the monitoring device 21 breaks down. Means for transmitting the status to the exchange 11 is described in the section 4.5.5 Network Indicator Bit of “Technical Reference TR-NWT-000397 Issue 2, January, 1991” issued by Bellcore (Bell Communication Research).
[0004]
That is, in the line monitoring system by the Bellcore, as a precondition, a bit arranged in nib bits (overhead bits (M channel)) between the exchange 11 and the monitoring device 12. ANSI T1.601-1992 (hereinafter referred to as “ANSI”). It is necessary to support the failure information notification means according to the above. In this notification means, during normal operation, the monitoring device 12 outputs nib = "1", and the exchange 11 can detect this and display normality. Further, when an abnormality occurs in the line, it is possible to notify the exchange 11 of the abnormality of the line by sending nib = “0” from the monitoring device 12 to the exchange 11. The exchange 11 can detect this nib = "0" and display an abnormality. For example, the following five conditions can be given for sending nib = “0” to the exchange 11.
1) When the transmission quality in the metallic subscriber line transmission line is deteriorated from a predetermined value.
2) When the sync signal is lost.
3) When the signal from the monitoring device 21 is lost.
4) When a failure occurs between the monitoring devices 12 and 21.
5) When nib = "0" is received from the subscriber home 2 side.
[0005]
In this line monitoring system, the exchange 11 monitors the state of the subscriber premises rather than the monitoring device 12 by supporting the nib bit.
[0006]
[Problems to be solved by the invention]
However, some of the current exchanges 11 do not support the nib bit, and such an exchange 11 has a problem that it cannot monitor the state of the subscriber's home rather than the monitoring device 12.
The present invention has been made in view of such problems, and can monitor the state of the subscriber premises rather than the monitoring device from the switch without requiring conditions such as nib bit support by the switch 11. An object is to provide a line monitoring system.
[0007]
Another object of the present invention is to provide a line monitoring system capable of switching clock supply sources with high accuracy.
[0008]
[Means for Solving the Problems]
      In order to achieve this object, the line monitoring system of the present inventionThe first aspect ofFrom the exchangeMultiplexing and extending the plurality of lines by interposing an extended transmission system in the middle of a plurality of lines up to a plurality of terminal devices, the occurrence of a failure on the terminal device side than the extended transmission system and the extended transmission system A line monitoring system for notifying the exchange, wherein the extended transmission system includes a first monitoring device connected to the switching device side, a second monitoring device connected to the terminal device side, and the first monitoring device. An extension transmission line connected between the monitoring device and the second monitoring device, and the first monitoring device receives a clock signal from a predetermined line among a plurality of lines with the exchange. The second monitoring device monitors the occurrence of a failure on the terminal device side from the second monitoring device, and the failure signal is detected on any of the plurality of lines. When the occurrence of An RKD signal is set to a predetermined bit in the M channel corresponding to, and is output to the first monitoring device. The first monitoring device generates a failure in the extended transmission path or the second monitoring device. Or a line on which the RKD signal is set in the M channel is detected, it is determined whether the line on which the RKD signal is set matches the line that references the clock signal. In this case, the line that refers to the clock signal is switched to another line, and all the subscriber transmission lines on the exchange side or the subscriber side transmission line on the exchange side corresponding to the line on which the RKD signal is set are not used. A signal state or a signal synchronization loss state is set.
[0009]
        According to a second aspect of the present invention, in the first monitoring device, when the RKD signal set in the predetermined bit continues for 36 ms or more, the exchange corresponding to the line in which the RKD signal is set The subscriber transmission line on the side is set to a no-signal state or a signal synchronization loss state.
[0011]
The state of the signal that the monitoring device outputs to the exchange side in response to various abnormalities in this way is referred to as a remote knockdown (RKD) hereinafter.
In the line monitoring system, when the extension transmission system multiplexes and transmits signals of a plurality of subscriber lines, the first monitoring device connected to the exchange supplies the same reference clock as that of the exchange. In order to be able to operate without being individually received from outside, a timing signal for synchronization is generated with reference to a clock signal regenerated from a predetermined line among a plurality of subscriber lines with the exchange. Furthermore, when the first monitoring device connected to the exchange sets the state of the signal transmitted on the predetermined line among the subscriber lines to the no-signal state or the signal synchronization loss state, prior to that, By switching the subscriber line referring to the clock signal from the predetermined line to another line, the occurrence of a failure is notified to the exchange without affecting other subscriber transmission lines and the monitoring device itself.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A monitoring apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing an example of the configuration of a line monitoring system using a monitoring apparatus according to the present invention.
The exchange 31 in the center station 3 and the monitoring devices 32 and 33 are connected by a 2B1Q echo canceller transmission system defined by ANSI via a subscriber transmission line 34 including two metallic subscriber transmission lines. Yes. Here, an example is shown in which the subscriber transmission line 34 between the exchange 31 and the monitoring device 32 is one line, and the subscriber transmission line 34 between the exchange 31 and the monitoring apparatus 33 is eight lines. In addition, display devices 35 and 36 are connected to the exchange 31 and the in-office device, respectively, and display faults based on alarm signals from the exchange 31 and the in-office device.
[0013]
  Between the monitoring devices 32 and 33 in the center station 3 and the monitoring devices 41 and 51 in each home, for example, a digital signal format having a bandwidth of a nominal value of 1.5 Mbps is used, and an optical interface or an electrical interface is used. Link. At this time, the extension transmission lines 61 and 62, which are high-speed lines (HSL lines) of this electrical interface, use a space division directional multiplexing system that does not worry about near-end crosstalk (using physically separate lines for uplink and downlink, In general, two-way communication is used. The monitoring devices 32 and 33, the extension transmission lines 61 and 62, and the monitoring devices 41 and 51 constitute the extension transmission system of the present invention. In the monitoring devices 41 and 51, the subscriber transmission line43, 53Bits in the transmission frame received at 1 are multiplexed for one line or multiple lines, and transmitted to the monitoring devices 32 and 33 of the center station 3 via the extension transmission lines 61 and 62.
[0014]
In the case of the present embodiment, the number of multiplexed transmissions of the monitoring apparatus 41 is, for example, one line, and the number of multiplexed transmissions of the monitoring apparatus 51 is, for example, eight lines.
As shown in FIG. 2, for example, as shown in FIG. 2, the transmission frames in the extended transmission lines 61 and 62 include a user data area in which ISDN basic service (2B + D) data is multiplexed, and an M channel (Mch) defined by ANSI. And an area of inter-monitoring device data that is transmitted and received only between the monitoring devices 35 and 36 in the center station 3 and the monitoring devices 41 and 51 in the subscriber's home 4.
[0015]
In-home monitoring devices 41 and 51 and network termination units (NT) 42 and 52 to 52 are connected via subscriber transmission lines 43 and 53 to 53 in a 2B1Q echo canceller transmission system defined by ANSI. A subscriber transmission line 34 and a subscriber transmission line 43 connected to the monitoring device 32 of the center station 3 and a subscriber transmission line 43 of the subscriber's home 4 and a subscriber transmission line 34 and a subscriber's home connected to the monitoring device 33 of the center station 3 respectively. Each of the five subscriber transmission lines 53 constitutes a set of U reference point metallic subscriber lines. The signal synchronization method from the switch 31 to the network termination units 42, 52 to 52 is such that the transmission line clock component is obtained from any one of the subscriber transmission lines 34 from the switch 31 connected to the monitoring device 32 or 33. Dependent synchronization method to extract.
[0016]
The network terminal units 42 and 52 to 52 and the terminal devices (TE) 44 and 54 to 54 in each home are connected via S / T reference point transmission lines 45 and 55 to 55.
In this way, in the line monitoring system, the IS reference basic service is provided by extending the U reference point metallic subscriber line from the exchange 31 to the network terminal units 42 and 52 to 52 in the subscriber homes 4 and 5 by the extension transmission system. is doing.
[0017]
The monitoring devices 41 and 51 detect a failure in the network termination units 42 and 52 and the subscriber transmission lines 43 and 53 and send a signal (RKD signal) indicating RKD to the monitoring devices 32 and 33 of the center station 3. Sending.
As a method of transmitting the RKD signal by the monitoring devices 41 and 51, for example, signals transmitted / received only between the monitoring devices 41 and 51 on the subscriber premises 4 and 5 side and the monitoring devices 32 and 33 on the center station 3 side (for example, There is a method of transmitting to the monitoring devices 32 and 33 of the center station 3 using the data between monitoring devices shown in FIG. Of the transmission frame standards on the existing subscriber transmission lines 34, 43, 53, the unused bits in the M channel are used to send this RKD signal to the center station via the extension transmission lines 61, 62. There is a method of transmitting to three monitoring devices 32 and 33.
[0018]
Hereinafter, the description will be given mainly using an example in which the M channel is used. Specifically, in this method, a bit portion fixed to “1” or nib can be used in the M channel of the transmission frame. Note that nib is a future reserved bit as described above, and is a bit that is not defined at least in ANSI. On the other hand, when using data between monitoring devices, for example, a specific bit of data between monitoring devices can be used. When the inter-monitoring device data is used, even if the exchange uniquely uses a bit or nib or the like that is fixed to “1” of the M channel, there is no fear of affecting the operation of the exchange. Thus, in this embodiment, it becomes possible to multiplex this RKD signal to an empty channel other than the main signal (2B + D in ISDN) and transmit it to the center station 3 side.
[0019]
The only difference in the configuration of the monitoring devices 32 and 33 of the center station 3 is the difference in whether or not they are for a plurality of lines, and the configuration is almost the same, so here the configuration of the monitoring device 33 is representatively shown in FIG. This will be described with reference to the drawings. Referring to FIG. 3, the monitoring device 33 includes a high-speed line interface processing unit 33a connected to the extension transmission path 62, a high-speed line framer 33b that multiplexes or separates signals, a time division switch 33c, a subscriber home U interface (hereinafter referred to as “U-I / F”) processing units 33d to 33g, which respectively correspond to the subscriber transmission line 53 on the 5 side and generate a clock signal from the received signal from the exchange 31; Clock source selection means 33h for selecting a clock signal from an arbitrary UI / F processing unit or high-speed line framer 33b among the F processing units 33d to 33g, and a timing for synchronization based on the selected clock signal Timing generating means 33i that generates a signal and supplies it to each part via a synchronization bus 33l, and control means 33 that controls these parts. It is composed of a.
[0020]
In the U-I / F processing units 33d to 33g, as shown in FIG. 4, the 2B + D interface 70 inputs and outputs 2B + D user data to and from the time division switch 33c. The input user data is once taken into the transmission FIFO 71, and then the basic frame and M channel (Mch) data are collected by the framer 72 to form a super frame. The Mch data is input from the CPU 33 via the CPU bus 33k from the control means 33j. The transmission circuit 73 transmits this super frame to the exchange 31 via the external line interface 74.
[0021]
The receiving circuit 75 receives signals from the exchange 31 via the external line interface 74. From this received signal, the demodulation circuit 76 and the clock recovery circuit 77 extract a clock component. The clock generation circuit 78 supplies, for example, a clock signal for synchronization of 8 kHz used in the network termination units 42 and 52 to 52 from the exchange 31 to the clock source selection unit 33h, and the U-I / F processing unit. A high-speed clock signal used inside the chip is simultaneously generated and supplied to each unit in the U-I / F processing unit.
[0022]
The echo canceller 79 is used to remove a transmission signal that has entered the receiving circuit 75 via the external line interface 74. That is, the echo canceller 79 performs an appropriate gain adjustment and delay time adjustment on the transmission signal and outputs it to the demodulation circuit 76 to cancel the transmission signal component from the reception signal component. In this way, each of the U-I / F processing units 33d to 33g can accurately reproduce the synchronization clock signal from the received signal.
[0023]
The received signal from the demodulation circuit 76 is divided into a basic frame and Mch data by the deframer 80. The basic frame is once taken into the reception FIFO 81 and then output from the 2B + D interface 70 to the time division switch 33c via the serial bus 33m. Further, the Mch data is output to the control circuit 82 and from there to the control means 33j via the CPU control port 83 and the CPU bus 33k.
[0024]
For example, among 2B + D data corresponding to the eight subscriber transmission lines 53 to 53 shown in FIG. 1, 2B is B11, B12, B21, B22,..., B81, B82, and D data is D1, D2. , ..., D8, the data B11, B12, B21, B22, ..., B81, B82, D1, D2, ..., D8 in this frame are allocated in the time slot shown in FIG. Output to the time division switch. Further, the control means 33j sequentially outputs the M channel data of all the lines and the inter-monitoring device data to the time division switch 33c via the serial bus 33n at the timing of time slots 0 to 5.
[0025]
The monitoring devices 41 and 51 are also connected to the subscriber transmission lines 43 and 53 to 53 are the network termination units 42 and 52 to 52, and are connected to the extension transmission lines 61 and 62 are the monitoring devices 32 and 52. The configuration is the same as that of the monitoring device 33 shown in FIG. However, the clock source selection unit 33h does not select the clock signal from the UI / F processing unit, and normally synchronizes with the monitoring devices 32 and 33 by selecting the clock signal from the high-speed line framer 33b. .
[0026]
Here, in the monitoring devices 41 and 51, the control means 33 j changes the vacant bit in the M channel corresponding to the failed metallic subscriber transmission line 53 from, for example, “1” to “0”, thereby RKD. It is possible to output a signal. The Mch data and the inter-monitoring device data output from the control means 33j at the timings of the time slots 0 to 5 are converted into the time slot 18 shown in FIG. 5 by the time division switch 33c, and then the high-speed line framer 33b and the high-speed line frame 33b. The data is output onto the extension transmission lines 61 and 62 via the line interface processing unit 33 a and transmitted to the monitoring devices 32 and 33.
[0027]
Here, the time slots 19 to 23 on the extended transmission paths 61 and 62 are assigned to the inter-monitoring device data. The time slots 24 to 31 are time slots that are ignored on the high-speed line framer 33b and do not exist on the extended transmission lines 61 and 62.
Next, the operation at the time of RKD processing for forcibly stopping the signal supply to the exchange 31 by the monitoring device 33 will be described. In this embodiment, a case where a clock signal is supplied from the first subscriber transmission line 34 and a failure occurs in the corresponding first subscriber transmission line 53 will be described as an example.
[0028]
First, when a failure such as a disconnection occurs in the first subscriber transmission line 53, the monitoring device 51, for example, passes the first subscriber transmission line 53 after a time of about 480 ms defined in the above-mentioned ANSI has elapsed. Detect link down. Then, the monitoring device 51 immediately changes the idle channel in the M channel corresponding to the first subscriber transmission line 53 in the transmission frame set in the extension transmission path 62 from “1” to “1”. Instead of “0”, it is transmitted to the monitoring device 33 as an RKD signal.
[0029]
In the monitoring device 33, as shown in FIG. 3, when the high-speed line framer 33b receives the transmission frame via the extension transmission path 62 and the high-speed line interface processing unit 33a, the time division switch 33c receives the M channel from the frame. Is transferred to the control means 33j. Also, 2B + D user data in this transmission frame is output to the U-I / F processing units 33d to 33g of the corresponding line via the time division switch 33c.
[0030]
When this M channel is input, the control means 33j detects the RKD signal in the M channel, recognizes the link down in the first subscriber transmission line 53, and corresponds to the U-I / F processing unit ( For example, in 33d), the process proceeds to RKD processing. Prior to the processing, the control means 33j examines the signal states of the respective U-I / F processing units 33e to 33g. Then, the control unit 33j uses the clock source selection unit 33h so that the U-I / F processing unit effective at that time other than the U-I / F processing unit 33d that performs RKD processing is used as a new clock supply source. The switching is controlled to reset the clock supply source, and the clock signal generated by the clock generation circuit 78 of the newly selected U-I / F processing unit (for example, 33e) is captured. In this case, since there may be a case where there is no effective UI / F processing unit serving as a clock supply source, the timing generating unit 33i is provided with a self-running function, and the timing generating unit 33i performs the self-running function. It is also possible to set the running clock source as a clock supply source for synchronization.
[0031]
When the switching of the clock supply source is completed, the control means 33j then causes the UI transmission / reception unit 33d to temporarily place the subscriber transmission line 34 on the exchange 31 side into a no-signal state or a signal synchronization loss state. A control signal is transmitted via the bus 33k. This control signal is taken into the control circuit 82 from the CPU bus 33k via the CPU control port 83 in the UI processing unit 33d. The control circuit 82 performs control for stopping the framer 72, the transmission circuit 73, the reception circuit 75, and the deframer 80, for example, for a temporary period (for example, about 1 second) or a period until this failure is recovered. The function of the subscriber transmission line 34 is stopped. At the same time, the control means 33j outputs an alarm signal indicating a failure of the extended transmission system to the display device 36.
[0032]
    Further, the control means 33j of the monitoring device 33 can also detect failures in the extended transmission system such as the home monitoring device 51 and the extended transmission path 62. That is, when a failure occurs in the extended transmission system, the state of the received signal of the high-speed line framer 33b becomes no signal. The control means 33j is a high speedLineframer33bA period during which this no-signal state is detected by notification from the CPU bus 33k from the time to the U-I / F processing units 33e to 33g temporarily (for example, about 1 second) or until this failure is recovered , A control signal for causing the subscriber transmission line 34 to be in a no-signal state or a signal synchronization loss state is transmitted via the bus 33k. At the same time, the control means 33j outputs an alarm signal indicating a failure of the extended transmission system to the display device 36.
[0033]
Upon receiving this control signal, the U-I / F processing units 33e to 33g change the signal state of the subscriber transmission line 34 to a no-signal state or a signal synchronization loss state. As a result, the exchange 31 detects that a failure has occurred in the subscriber line transmission system such as the subscriber transmission lines 43 and 53 to 53 or the extension transmission system, and outputs a detection signal to the display device 35.
Based on this detection signal, for example, the display device 35 turns on an alarm lamp installed in the device itself to notify the occurrence of a failure. Further, when the display device 36 receives an alarm signal indicating a failure in the subscriber line transmission system or the extension transmission system from the control means 33j, based on these detection signals, for example, an alarm lamp installed in the own device is turned on. To report the failure. For example, the display device 35 turns on an alarm lamp in its own device even when a failure occurs in either the subscriber line transmission system or the extension transmission system. The display device 36 turns on an alarm lamp in its own device only when a failure occurs in the subscriber line transmission system, and turns off this alarm lamp when a failure occurs in the extended transmission system. Thereby, the supervisor can recognize whether the failure is in the subscriber line transmission system or the extension transmission system by the combination of blinking of the alarm lamp.
[0034]
As described above, in this embodiment, when the control unit 33j detects a failure in the subscriber line transmission system or the extension transmission system, the clock source selection unit 33h detects the failure in the clock supply source (U-I / F processing). Switch to a new clock supply source. After that, the control means 33j controls the corresponding U-I / F processing unit to temporarily set a certain period or a period until the failure is recovered. To. Therefore, the exchange 31 can detect the occurrence of a failure by detecting this no-signal state or loss of signal synchronization, and at the time of RKD on a certain line, a synchronization abnormality due to a clock signal slip or the like on another line is detected. Can be prevented.
[0035]
As described above, in this embodiment, the RKD is performed on the subscriber transmission line that is the failed clock supply source after the clock supply source is switched to another clock supply source before the RKD. The clock supply source can be satisfactorily switched without adversely affecting other lines.
In this embodiment, the clock supply source switching process is performed as described above. However, since all U reference points of the monitoring devices 41 and 51 operate sufficiently in synchronization with the same clock source, The clock signal jitter and frame slip in the monitoring devices 32, 33, 41 and 51 due to the switching of the clock supply source are not a problem at all.
[0036]
In this embodiment, the time difference between the clock switching and the RKD of the subscriber transmission line 34 on the exchange 31 side can be arbitrarily set. For example, the maintenance bit (M bit) normally used for ISDN basic interface metallic subscriber transmission is recognized by ANSI as having a continuation of 3 frames (ie, 36 ms) or more. Based on this, it is appropriate to provide a time difference of about 36 ms. At this time, for example, when the RBD instruction is given from the monitoring devices 41 and 51 to the monitoring devices 32 and 33 by using the nib bit, the same 36 ms as that for recognizing a normal change in the state of the M channel is used. If it is a time difference, the time difference setting function can be incorporated into the monitoring devices 32 and 33 very easily. For example, when the monitoring devices 32 and 33 first detect nib = 0, the switching of the clock supply source is started as a precautionary measure, and the actual RKD is entered when nib = 0 continues for 3 frames (36 ms). When a method for performing a simple process is adopted, it becomes possible to incorporate functions very easily.
[0037]
Further, as a desirable factor for setting this time difference, there is a clock signal switching speed inside the monitoring devices 32 and 33. Normally, the switching of the clock supply source should be completed in a time of 1 ms or less, but it is also possible to set a sufficiently long time difference for safety, for example, 48 ms for 4 frames, or about several hundred ms. It is also possible to set a time difference of.
[0038]
Further, in this embodiment, when the extension transmission lines 61 and 62 are disconnected as described above, it is preferable to disconnect all the subscriber transmission lines 34, and as a result, all the clock supply sources are disconnected. Therefore, the status determination of the subscriber transmission line 34 is meaningless. Therefore, in the present invention, it is determined by the monitoring devices 41 and 51 on the center station 3 side or on the subscriber homes 4 and 5 side whether or not all the subscriber transmission lines 34 are disconnected at the same time. It is possible to incorporate an algorithm for switching the clock supply source.
[0039]
Further, in a situation where all the subscriber transmission lines 34 are disconnected, the clock supply to the monitoring devices 41 and 51 on the subscriber homes 4 and 5 side is temporarily cut off. Even under such circumstances, in order to ensure the operation of the ISDN extension device, it is also possible to have a configuration having a free-running clock source inside. In this case, the free-running clock source can be configured using a known technique such as using the free-running mode of the digital PLL. However, it takes 1 ms or more to stabilize the free-running clock source. The case is also fully considered. For this reason, it is also effective to determine the time difference between the switching of the clock supply source and the RKD in consideration of the stabilization time of the free-running clock source. For example, when the time required for stability is 10 ms, it is effective to set a time difference larger than this. In addition, a method of setting the time difference to a different value only when switching to the free-running clock source is effective for improving the operating speed of the system.
[0040]
Further, the control means 33j of the monitoring devices 32 and 33 displays an alarm signal only when there is a failure in the subscriber line transmission system composed of the subscriber transmission lines 43 and 53 to 53 and the network termination units 42 and 52 to 52. It is also possible to output to. In addition to the lighting and extinguishing of the alarm lamp, the display device 36 can also periodically blink. Thus, by using a plurality of alarm lamp operating methods, it is possible to notify, for example, the contents of the trouble and troubles other than the trouble of the subscriber line transmission system and the extension transmission system.
[0041]
In this embodiment, for example, in the case of a failure in the subscriber line transmission system, the subscriber transmission line 34 is set to a no-signal state, and in the case of a failure in the extended transmission system, the subscriber transmission line 34 is signaled. It is also possible to set the state of loss of synchronization, and the exchange 31 can recognize whether the failure that has occurred is a subscriber line transmission system or an extended transmission system by detecting these states of the subscriber transmission line 34. It becomes possible.
[0042]
Further, in this embodiment, the case where it is used in the line monitoring system between the center station 3 and the subscriber homes 4 and 5 has been described. However, the present invention is not limited to this, and a configuration as shown in FIGS. 6 and 7 is also possible. That is, as shown in FIG. 6, for example, a remote device 40 is installed on the ground or on a utility pole, a monitoring device 41 is provided therein, and a network terminal unit 52 and a terminal device 54 are provided in each subscriber house 5. It can also be used in a structured system. Further, as shown in FIG. 7, a monitoring device 41 is provided in the remote device 40, and for example, a network terminal unit 52 and a terminal device 54 are provided in each pole device 50 provided on a utility pole, etc. The antenna 60 may be provided outside the pole apparatus 50, and the antenna 60 may be used for a system configured to transmit a signal to the PHS or the like wirelessly.
[0043]
Further, as shown in the second embodiment of FIG. 8, the line monitoring system of the present invention can be applied even when the transmission interface to be extended or multiplexed is an electrical interface. In the following drawings, the same components as those in FIG. 1 are denoted by the same reference numerals for convenience of explanation. In this case, for example, the monitoring devices 32 and 41 are connected to a transmission network 63 such as a general public line network that relays a main signal and a failure signal composed of electric signals via an electric interface 61 (including an extended transmission path). Therefore, when a failure occurs between the electrical interface 61 connected to the monitoring device 32 and the network terminal unit 42, the monitoring device 32 causes the subscriber transmission line 34 to be in a no-signal state, thereby causing a failure in the line to the exchange 31. You can tell what happened.
[0044]
The line monitoring system of the present invention can also be applied to a case where two or more extended transmission systems are provided to further extend the transmission line as shown in the third embodiment of FIG. That is, referring to FIG. 9, in this embodiment, there is a space between an extended transmission system composed of the monitoring device 32, the transmission network 63, and the monitoring device 64 and an extended transmission system composed of the monitoring device 65, the transmission path 63, and the monitoring device 41. It is configured to be connected by a subscriber transmission line 66. The monitoring device 65 receives the RKD signal from the home monitoring device 41 via the transmission network 63, detects a failure in the extended transmission system such as the monitoring device 41 or the transmission network 63, and the failure based on this reception and detection. The signal is output to the subscriber transmission line 66. The monitoring device 64 captures the RKD signal from the monitoring device 65, detects a failure in the subscriber line transmission system such as the monitoring device 65 and the subscriber transmission line 66, and transmits the RKD signal based on this capture and detection. The data is transmitted to the monitoring device 32 via the network 63. The monitoring device 32 performs RKD based on the received RKD signal and notifies the exchange 31 of the occurrence of a failure.
[0045]
Thus, in this embodiment, even in a system in which the transmission path is further extended, a failure in the subscriber line transmission system and the extended transmission system can be detected and the failure can be reliably notified to the exchange 31 of the center station 3. it can.
Note that the monitoring device 65 of the present invention is not limited to this embodiment. For example, instead of transmitting this fault signal, the signal state of the subscriber transmission line 66 is set to no signal or signal synchronization loss state, and the monitoring device 64 It is also possible to notify.
[0046]
In these embodiments, when a failure in the subscriber line transmission system and the extension transmission system is detected, the monitoring lines 32 and 33 are temporarily set in the subscriber transmission line 34 for a certain period or a period until the failure is recovered. Since the signal state or the signal synchronization loss state is set, the exchange 31 can monitor the state on the subscriber homes 4 and 5 side rather than the monitoring devices 32 and 33 without requiring a condition such as support of nib bit. .
[0047]
【The invention's effect】
As described above, according to the present invention, an extension transmission system is interposed in the middle of a plurality of lines from an exchange to a terminal device, and the plurality of lines are multiplexed and extended. From the extension transmission system and the extension transmission system, Is a line monitoring system for notifying the occurrence of a failure on the terminal device side to the exchange side, wherein the extended transmission system is a first monitoring device connected to the exchange side and a first monitoring device connected to the terminal device side. Two monitoring devices and an extended transmission line connected between the first monitoring device and the second monitoring device, and the first monitoring device connected to the switch is connected to the switch. A synchronization timing signal is generated with reference to a clock signal from a predetermined line among a plurality of lines in between, and the second monitoring device generates a failure on the terminal device side from the second monitoring device. Detect and indicate the failure Harm information is notified to the first monitoring device, and when the first monitoring device detects an occurrence of a failure on the extended transmission system or on the terminal device side of the extended transmission system, a signal output to the exchange side In this state, the occurrence of the failure is notified to the exchange side, and at the time of the notification, the first monitoring device is transmitted through a predetermined line referring to the clock signal. When the signal state is changed to the no-signal state or the signal synchronization loss state, the line that refers to the clock signal is switched from the predetermined line to another line prior to that. The state of the subscriber premises can be monitored from the exchange without using the monitoring device, and the problem of the synchronization abnormality that the RKD processing of the predetermined line affects the communication of other lines It can be prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of the overall configuration of a line monitoring system according to the present invention.
2 is a frame format showing a schematic configuration of a transmission frame transmitted by the line monitoring system shown in FIG. 1. FIG.
FIG. 3 is a configuration diagram illustrating an example of a configuration of the monitoring device illustrated in FIG. 1;
4 is a configuration diagram illustrating an example of a configuration of a UI / F processing unit illustrated in FIG. 3;
FIG. 5 is a diagram for explaining the relationship between data and time slots;
6 is a block diagram illustrating another configuration example on the terminal device side from the extension transmission path illustrated in FIG. 1; FIG.
FIG. 7 is a block diagram showing still another configuration example.
FIG. 8 is a block diagram showing a second embodiment of the configuration of the line monitoring system according to the present invention.
FIG. 9 is a block diagram showing a third embodiment.
FIG. 10 is a block diagram showing a configuration of a line monitoring system using a conventional extended transmission method.
[Explanation of symbols]
1,3 Center station
2,4,5 subscriber's house
30, 61, 62, 66 Extension transmission line (HSL line)
11,31 exchange
12, 21, 32, 33, 41, 51, 64, 65 Monitoring device
13, 24, 34, 43, 53 Subscriber transmission line
22, 42, 52 Network termination (NT)
23, 44, 54 Terminal equipment (TE)
33a High-speed line I / F processor
33b High-speed line framer
33c Time division switch
33d-33g U-I / F processor
33h Clock source selection means
33i Timing generation means
33j Control means
33k, 33l, 33m, 33n bus
40 Remote device
45,55 S / T reference point transmission line
50 Pillar equipment
60 antenna
63 Transmission network

Claims (2)

An extension transmission system is interposed in the middle of a plurality of lines from the exchange to a plurality of terminal devices, and the plurality of lines are multiplexed and extended, and the failure on the terminal device side of the extension transmission system and the extension transmission system is reduced. A line monitoring system for notifying the exchange of occurrence,
Said extension transmission system, the first monitoring device connected to the exchange side, a second monitor connected to the terminal device side, and the first monitoring device and the second monitoring device An extension transmission line connected between
Wherein the first monitoring device generates a timing signal for synchronization with reference clock signals from a predetermined line out of a plurality of lines between the exchange,
The second monitoring device monitors the occurrence of a failure in the terminal device side of the second monitoring device, occurrence of the failure of one of the plurality of lines when it is detected, corresponding to the line RKD signal is set to a predetermined bit in the M channel and output to the first monitoring device,
It said first monitoring apparatus detects the occurrence of a failure in the extension transmission line or said second monitoring device, or upon detecting the line the RKD signal in said M channels is set,
If the line on which the RKD signal is set matches the line that refers to the clock signal and matches, the line that refers to the clock signal is switched to another line,
Line monitoring characterized in that all the subscriber side transmission lines on the exchange side or the subscriber side transmission lines on the exchange side corresponding to the line on which the RKD signal is set are put into a no-signal state or a signal synchronization loss state. system. When the RKD signal set in the predetermined bit continues for 36 ms or longer, the first monitoring device sends no signal to the subscriber transmission line on the exchange side corresponding to the line in which the RKD signal is set. 2. The line monitoring system according to claim 1, wherein the line monitoring system is in a state or a signal synchronization loss state .

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