JPS5945728A - Failure retrieval system - Google Patents

Abstract

PURPOSE:To simplify the constitution of a circuit and to miniaturize the size, by using a low-frequency signal extracting means at a monitor circuit in common for a bidirectional transmission line. CONSTITUTION:A failure retrieval signal in an incoming transmission line, e.g., is discriminated at a discriminating system 22-1 at a failure retrieval and applied to an input of a gate 45. A signal is interrupted on an outgoing transmission line and another input of the gate 45 is at ''1''. Thus, the failure retrieval signal is applied to an FF46 via the gate 45, a low-frequency signal is reproduced and when the signal frequency is coincident with a frequency f1 assigned to the own device, an output is generated from a comparator 42, a gate 44 is opened and the failure retrieval signal is returned to the outgoing transmission line via a reproducing system 24-2. Since the gate 45 is provided in this way, the FF46 and an amplifier 47 are used in common to both the relay transmission lines to control the detection of the failure retrieval signal and the return.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a digital relay line, particularly a relay line having repeaters for both directions in the same repeater, when searching for faults on the terminal station side. This paper relates to a fault search method.

Conventional technology and problems Relay lines, especially digital relay lines used in submarine communications, use separate transmission paths for upstream and downstream directions, and a repeater for upstream and a repeater for downstream are used. A method is often used in which a type of relay device (hereinafter referred to as a relay device) housed in the same housing is placed between both end station devices to form a relay transmission path.

FIG. 1 explains the configuration of such a digital trunk line. In the same figure, 1 and 2 are terminal equipment, and 3
-1. ．． 3-2. -., 3-n are relay devices, respectively, and relay devices 3-1, 3-2, . −． 3-n are respective uplink repeaters 4-1. Downlink repeater 5-1, uplink repeater 4-
2. It has a downlink repeater 5-2, an uplink repeater 4-n, and a downlink repeater 5-n.The signal in the down direction from the terminal device 1 is indicated by a broken line. Repeater 4-1.4-2. ---． 4-n is sequentially transmitted and reaches the terminal device 2, and the downlink signal from the terminal device 2 is transmitted to the repeaters 5-n, -, 5- via the downlink transmission path indicated by the broken line.
2 and 5-1 are transmitted sequentially and reach the terminal device I.

Further, FIG. 2 explains the configuration of each repeater.

In the figure, reference numeral 11 denotes a repeater, which converts the signal on the transmission line 12 into medium s+l and transmits it to the transmission line 13. Repeater 11
14 is an equalization amplifier, 15 is an identification circuit, 16 is a timing extraction circuit, 17 is a regeneration circuit, and 18 is a monitoring circuit. The signal from the transmission line 12 is first applied to the equalization amplifier 14 in the repeater 11, where amplification and amplitude equalization are performed, and then applied to the identification circuit 15, and then the timing extraction circuit I6.
1''' of signal level depending on the timing signal from
A determination of “0” is made. At this time, the timing extraction circuit 1
6 extracts the clock component of the transmission line from the output of the equalization amplifier 14 and supplies it to the identification circuit 15 as a timing signal. The reproduction circuit 17 reproduces the signal based on the determination result of the identification circuit 15 and outputs it to the transmission line 13 .

In such a relay line, if a fault in the transmission line is detected in one of the end station devices, for example by checking the parity of the transmission special code, then the -71° transmission line is taken offline and the A search pattern signal containing a predetermined low frequency (for example, ri) is sent out from the terminal equipment, and each relay device extracts the low frequency component included in the search signal using a monitoring circuit, and then A method is used in which when the frequency assigned to the device is used, the search signal is warped and returned to the transmission path in one direction to form a loop, thereby searching for a fault in the transmission path.

In FIG. 1, the frequency f1 is
This signal indicates that the signal on the -1 Yuri line has been looped back from repeater 4-2 to repeater 5-2 to the downlink. Further, in FIG. 2, a monitoring circuit 18 is provided to detect a fault search signal and control loopback based on the output of the identification circuit.

FIG. 3 shows the configuration of a conventional fault detection method for detecting such a fault detection signal and controlling transmission line loopback. In the figure, 21-1° 21-2 is an equal system (IEQ), 22-L22-2 is an identification system, 23-1° 23-2 is a timing system, 24-1 and 24-2 are reproduction systems, 25 are monitoring systems, each of which corresponds to the equalizing amplifier 14 in FIG. Identification circuit 15. Timing extraction circuit 16. Regeneration circuit 17. The subscript 1 corresponds to the monitoring circuit 1, the subscript 1 corresponds to the 11th transmission line, and the subscript 2 corresponds to the downstream transmission line. In the identification system 22-1.22-2, 31-1.31-2 is a D type flip-flop (r', l, 32-1.32-2 is a gate, and the reproduction system 24-1, 24- In 2, 33-1.33~
2 is a gate, and 34-1.3.1-2 is a regenerative amplifier, and the subscript 1.2 indicates that these are connected to the 2 transmission line and the down transmission line, respectively. Monitoring system 25
, 35.36 is a gate, 37 and 38 are T-type flip-flops (F, ri), 39.40 is an amplifier, 41 is a bandpass filter, 42 is a comparator, and 43
．． 44 is a gate.

In FIG. 3, the signal on the upstream transmission path is equalized and amplified through the other system 21-1, and then extracted by the timing system 23-1 at F and F 31-1, identified by the Ij hook, and then transmitted to the NRZ. (Non Return to Z
ero) data, and this signal is further output by the timing system output 1 to the gate 32-1 via the l?Z (Return.

Zero) signal and applied to one input of the gate 1-33-1. When the fault search signal is not detected in the monitoring system 25, the signal "1" is inputted to the other input of the gate 1-33-1 from the gate 1-43, and therefore the RZ multiplied signal of the identification system 22-1 is input. C) The signal is applied to the regenerative amplifier 34-1 via the regenerative amplifier 33-1, and the regeneratively amplified signal is sent out to the second transmission line. Similarly, the signals on the downlink transmission line are also applied to the other systems 21-2. Timing system 23-2. Via the identification system 22-2, when the output of the gate 44 in the monitoring system 25 is "1", it is reproduced and outputted through the reproduction system 24-2. In addition, the gates 32-1 and 32-2 receive signals from the timing system 23-1 and 23-2, respectively.
T is input, and when a failure occurs in each timing system, this signal becomes "0", thereby blocking each gate 32-1 and 32-2 and prohibiting signal transmission.
It is designed to be L.

On the other hand, when a fault in the transmission path is detected at the terminal station, the -circuit transfer path is taken offline and a search signal containing a predetermined low frequency signal is sent from the terminal station to each relay device. Assuming that a search signal is now sent to the upstream transmission path, this signal is identified by the identification system 22-1 and input to F, l' 37 via the gate 35. In F and F 37, a low frequency signal is regenerated from the search signal, and the regenerated signal is amplified in an amplifier 39 and then input to a filter 41. The frequency f1 of the reproduced signal is applied to the filter 4.
1, an output signal of a constant level is generated at the output of the filter 41. The comparator 42 compares the peak value of the output level with a reference value, and generates an output when the peak value is greater than the reference value, thereby determining that the signal is a fault search signal for the relay device. The output of comparator 42 is applied to gate 44 to open it, so that the identified fault search signal is passed from identification system 22-1 to gate 35. After passing through gate 44, the playback game on the downlink transmission line)
33-2.

The other human power at the gate 33-2 is connected to the identification system 22-2 on the condition that the signal on the downlink transmission line is cut off.
Since the signal "1P" is added from the gate 1-32-2 of the second gate, the fault search signal is sent from the gate 1-33-2 to the downlink transmission path via the regenerative amplifier 34-2. A return loop is formed from the terminal device through the uplink transmission path, the relay device, and the downlink transmission path, and by forming such a loop, it is determined that the loop portion including the relay device is normal. By repeating this procedure for each relay device, it is possible to search for faults in the relay line.The same is true when searching for faults from the downlink transmission path.When searching for faults, the signals on the transmission path in the opposite direction can be searched for. The reason for this is to prevent the interference operation caused by the mixture of the fault search signal and the transmission line signal.In addition, in FIG.
The signals indicated by broken lines input from the regenerative amplifier 34-2 to the gate 43 are for turning off the respective gates 44 and 43 in the event of a failure in the regeneration system. This prevents the search signal from being looped back.

In this way, in the conventional fault detection method, when a fault in the transmission path is detected at the terminal equipment, the transmission path is taken offline and the terminal station transmits a predetermined low frequency signal to each relay equipment. By sending the fault search signal containing the signal to the transmission path and extracting this low-frequency signal at the corresponding relay device, the fault search signal is looped back to the relay transmission path in the opposite direction to form a loop, thereby performing the fault search. However, conventionally, flip-flops and amplifiers for reproducing low-frequency signals have been installed in the monitoring circuit provided for each repeater, corresponding to the transmission paths in both directions, which is not only wasteful in terms of structure, but also wasteful. The device is
There was a problem that miniaturization was hindered.

OBJECT OF THE INVENTION The present invention attempts to solve the problems of the prior art, and its purpose is to add one gate circuit to the configuration of the conventional monitoring circuit.
The means for extracting low frequency signals in the monitoring circuit can be used in common for transmission paths in both directions, thereby simplifying and downsizing the circuit configuration and creating a circuit format that eliminates waste in the circuit configuration. It is about providing.

Embodiment of the Invention FIG. 4 shows the configuration of an embodiment of the fault search method of the present invention. In the same figure, the same parts as in FIG.
7 is an amplifier, F, I' 46. Amplifier 47 is the same as p, p3'1.38 and amplifier 39.40 in FIG. 3, but is provided in common for both transfer paths.

In FIG. 4, the operation when no fault search is performed is the same as in FIG. 3. When searching for a fault, for example, a fault searching signal on an uplink transmission path is identified by the identification system 22-1, and is applied to one input of the gate 45 via the gate 35. At this time, the downlink transmission line is in a signal-off state, and "1" is applied from the gate 36 to the other input of the gate 45 as in the case of FIG. After F, l? 46 and a low frequency signal is regenerated. The regenerated low frequency signal is amplified in an amplifier 47 and then passed through a filter 41 . Comparator 42
3, the determination is made in the same manner as in the case of FIG. 2 and is turned back to the downlink transmission path to form a loop.

In this way, according to the configuration shown in FIG. 4, by providing the gate 45 in the monitoring system 25, the low frequency signal reproducing flip-flop 46 and the amplifier 47 can be used in common for the re-relay transmission line, thereby making it possible to carry out fault detection borrowing. - detection and loopback control can be performed.

FIG. 5 shows an example of a fault detection signal used in the fault detection method of the present invention, together with the configuration of each part related to its generation and detection. In the same figure, (A) shows only the parts related to the generation and detection of the fault search signal extracted for the terminal equipment side and the relay equipment side, respectively. In the same figure, 51 is the transmission line clock frequency f. oscillator, 52, 53 is a pseudo-random code (1) N code) generator, 54 is ant game-1, 55.56 is exclusive OR (fEX-OR) game], 57 is each raw silk; 5 is a delay circuit (τ) that delays the signal by 1 bit, 59 is a T-type flip-flop (F, F), and 60 is a bandpass filter with center frequency f1. .

In addition, (B) shows the signals of each part in FIG. 5 (A), and (
al is the output signal of the oscillator 57, (bl is the output signal of the IEX-OR gate 55, (C1 is the output signal of F, F 543, +d) is the output signal of the filter 60, and these signals are shown in FIG. The same symbols are also used in (8).

On the terminal equipment side, an oscillator 51 generates a clock having a transmission line clock frequency r and inputs it to PN code generators 52 and 53. The PN code generators 52 and 53 generate signals of 1)N codes, each having a mark rate of 1/2, in response to a clock f. Both PN code signals are applied to an AND gate 54 to generate a PN code signal with a mark rate of 1/4 at its output, and this signal is applied to one input of an EX-OR gate 55. The oscillator 57 generates a low frequency signal (a), which is sent to the EX-OR circuit 5.
5 is added to the other input.

As a result, a signal (bl) in which the mark rate alternately changes between 1/4 and 3/4 according to the polarity of the signal (al) is obtained as the output of the IEX-OR circuit 55. Directly, the other signal is delayed by 1 bit in the delay circuit 58 and input to the IEX-OR gate 56, and a signal having a constant mark rate of about 37.5% is obtained as an output signal. It is sent out to the transmission line as a search signal.On the relay device side, the human signal is F, r'
59 clock terminal C. The d output is fed back to the data input terminals of F and F2O, which causes a signal (
C1 is 17. It is obtained as the Q output of r' 59. By passing this signal (C) through the filter 60,
As its output, an output signal (d) of frequency f1 is obtained. In addition, here, EX-OR game 1-56 and delay circuit 58
The reason why the mark rate is changed depending on the transmission line signal is that the mark rate of a transmission line signal is normally about 50%, and therefore it is not desirable to set the mark rate to be much different from this because it will affect the operation of the transmission line. Regarding conversion of mark rate, for example, see Matsushita et al., “Remote measurement of bit error rate in digital transmission paths,” Journal of the Institute of Electronics and Communication Engineers, 76/11 V.
ol, J59-8 No.

11.

Effects of the Invention (2) According to the present invention, a relay device having both uplink and downlink repeaters is provided in the same device, and a signal of a specific frequency is transmitted from a fault search signal on one transmission path. In a fault detection method in which a fault detection signal is looped back to the other transmission line when the fault detection signal is extracted, when the transmission line on which the fault search is not performed is in a no-signal state, the signal is detected from the repeater identification circuit of the other transmission line. A gate is provided to pass the signal, and a flip-flop and amplifier are added to reproduce the fault search signal as a low frequency signal through the gate, and a specific frequency component is extracted from the output. Since the input signal is inputted to the input signal, a flip-flop and an amplifier are required, which simplifies the circuit configuration, reduces the circuit scale, and is economically advantageous.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a trunk line to which the present invention is applied;
FIG. 2 is a diagram showing the configuration of the repeater in FIG. 1, FIG. 3 is a block diagram showing the configuration of a conventional fault detection method, and FIG. 4 is a diagram showing the configuration of an embodiment of the fault detection method of the present invention. The block diagram in FIG. 5 is a diagram showing an example of a search pattern in the fault search method of the present invention. 1.2: Terminal device, 3-1.3-2. -, 3-n: Relay device, 4-1.4-2. −． 4-n, 5-1.5-
2. −． 5-n: Repeater, 12.13: Transmission line, 1
4: Equalization amplifier, 15: Identification circuit, 16: Timing extraction circuit, 17: Regeneration circuit, 18: Monitoring circuit, 21-1.
21-2 n equalization system (old J), 22-L22-2: Identification system, 23-1.23-2: Timing system, 24-1
．． 24-2=reproduction system, 25: monitoring system, 3l-L3]-2
n D type flip-flop (F, F), 32-
1.32-2: Gate, 33-1.33-2: Gate, 34-1.34-2: Regenerative amplifier, 35.36:
Gate, 37.38: T type flip-flop (
F, F), 39.40: Amplifier, old; Bandpass filter, 42: Comparator, 43, 44, 45: Gate,
A6; T type flip-flop, 47: Amplifier, 51
: Oscillator, 52.53 : Pseudo-random code (PN code) generator, 54: AND gate, 55.56 : II
F-transitive OR EX-OR) gate, 57: Oscillator,
58: Delay circuit (τ), 59: T-type free flow circuit, 6o two-hand pass filter Patent applicant Fujitsu Co., Ltd. Agent Patent attorney Gobe Tamamushi (3 others) Figure 1 Figure 2 Cause 1 Continued page @ Inventor Yoshihiro Sakai Inside Fujitsu Limited, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City (7) Inventor Shin Yonemoto Inside Fujitsu Limited, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City

Claims (1)

[Claims] Relay 1 devices that have repeaters for both the backward and forward directions within the same device are placed sequentially on the transmission path between both end stations, and in the event of a failure, the low frequency signal components assigned in advance to each relay device are transmitted from the end station. In a relay device using a fault search method, which sends a fault search signal containing a Gate means that opens on the condition that there is no signal on the transmission line on the side that is not searching for a fault and allows a signal separated from the repeater identification circuit on the side that is searching for the fault to pass through; and means for extracting a low frequency component from a fault search signal connected to the output of the gate means, the low frequency extraction means being shared by uplink and one-way repeaters. Search method.