JPS59107662A - Line supervisory system of time division directional control transmission system - Google Patents

Abstract

PURPOSE:To supervise an error characteristic with high accuracy without adding a new bit by utilizing that a DC balance of a burst signal is kept to detect a code error, and using the polarity of the 1st bit of a burst signal in opposite direction to use the result of error detection as a toward station alarm signal. CONSTITUTION:A code error detecting circuit 34 of a subscriber's equipment 17 is connected to an equivalent amplifier circuit 19 and a control circuit 32, and an output of the circuit 34 controls a line driver 25. Further, a code error detecting circuit 35 and a counter station alarm detecting circuit 36 are connected to an equivalent amplifier circuit 26 and a control circuit 33. The sum of 1s in a burst signal is discriminated by using a receiving pulse from the circuit 19 and a frame synchronizing signal from the circuit 32 at the circuit 34 of the subscriber side and the result is added to the circuit 25. When the result of discrimination, by this circuit 25 is an odd number, the polarity of the 1st bit of the next burst signal is inverted and the result is transmitted to a telephone station 11. Further, the circuit 36 discriminates the presence of inversion of the polarity of the 1st bit at each burst signal, allowing to detect an erroneous bit with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line monitoring system in a time-division direction control transmission system in which a transmission signal and a reception signal are time-compressed and bidirectional transmission is performed every burst period.

<Prior art> A time-division direction control transmission system is being researched as a digital subscriber line transmission system.3 On the other hand, with the shift to digital subscriber lines, maintenance tests for digital subscriber lines must be further enhanced. I have emphasized that it is important. In other words, it is necessary to constantly monitor the digital subscriber line during communication, and if four abnormalities are detected, a maintenance test must be carried out immediately to isolate the location of the failure. This improves the convenience of service for users. So, bottom,
After describing the operating principle of the time-division direction control transmission system, problems with the conventional retrospective monitoring system in this transmission system will be explained.

The principle of time-division direction control transmission method is, for example, IEEE Tra.
actions on communication
ns VOL, C0M-29, NO, 11, 1981
, P1565~PI372 [Time-5hared
TWO-Wired I) digital 5ubscr
iber'l'transmission 5yster
n and Its Application t.

the Digital 'l'elephone S
et J, bidirectional transmission is achieved using a two-wire line by time-compressing the digital signals to be transmitted and arranging them temporally so that the transmitted and received signals do not overlap. make something)

Hereinafter, 13 will be explained in detail using FIGS. 1 and 2.
In FIG. 1, a digital signal (speed variation: lr
',! The burst signal shown in FIG. 2 is generated by l i$ 13.
j Converted to B+. By connecting the line driver circuit 15 and the balanced cable 16 via the switch 14, this burst signal B1 is transmitted in the direction of the subscriber's home 17. At this time, the burst signal B1 from the telephone office 11 is equalized and amplified in the equalization amplifier circuit 19 by connecting the balanced cable 16 and the equalization amplifier circuit 19 through the switch 18 (through the switch 18). j
Converted to continuous/1 angle signal output terminal 22
is output to. Conversely) J1] From person's house 17 to telephone office 1]
When transmitting to the speed conversion circuit 2, the linear signal from the digital signal input terminal 23 is transmitted to the speed conversion circuit 2 using the same principle as above.
4. Line driver circuit 25, switch 18, balanced cable 16, switch 14, equalization amplifier circuit 26, and speed conversion circuit 27 are output, converted to burst signal B2 and transmitted, and then converted back to a continuous signal and digitalized. Signal output rabbit 1
9, in which the control circuits 31 and 32 are synchronized using the frame bits in the received burst signal reproduced by the bamboo amplifier circuit 26 or 19, and the switch], 4, 1.8 and speed conversion law ij! 1t 1.3 + 27 and 0.21.24, respectively, are controlled by h'J6.

In this transmission system, the reproduced/current signal may be erroneous due to causes such as crosstalk from other sources or garbled sounds. In order to determine on the receiving side whether or not this code error has occurred, it has conventionally been necessary to add an error code to the digital signal to be transmitted. Since the introduction of this error detection '$J number (transmission rate on the line bit rate) increases, code errors p are more likely to occur due to crosstalk, noise, etc. from the other four lines.

Another disadvantage is that the addition of a complicated error detection circuit increases the cost of the device.

<Summary of the invention> This invention is in the process of development without adding any new bits.
This invention provides a line monitoring knob type time-division direction control transmission system that can monitor the code error characteristics of a second line with high precision using a simple circuit. By using the fact that the DC balance of the burst signal is always maintained at (!?1), the presence or absence of a signal error is detected, and by using the polarity of the first bit in the burst signal in the opposite direction,
The code error detection result is transmitted as a game warning signal.

Embodiment Prior to a detailed explanation of the present invention, the frame structure of a burst signal will be explained. FIG. 3 shows an example of the frame structure of a burst signal of this transmission method. The reverse burst signal 1 consists of frame bits, information bits, signaling bits, and DC balance bits. Among these, the DC balance bit is a bit unique to this transmission method, and is a bit used to eliminate the DC component of the burst signal. In other words, if the DC balance of the burst signal is not ensured, the DC level will vary depending on the pattern, causing code amount interference and deteriorating the transmission characteristics.The fourth point is a specific example of the use of DC balanced bits. It is a diagram showing A. with the transmission gradient and j~. The case where MI code is used is shown. When transmitting a binary number "1" to the AMI signal, the polarity of the sending pulse is alternately changed. As shown in Fig. 4A, if the sum of "J" of these bits is an odd number for the frame bit, information bit, and 7 signaling bits in the burst signal, the DC balance bit is set to "1", and as shown in Fig. 4B As shown in the figure, if the number is even, it is set to "0". In this way, the mixture of "1"s in the burst signal is always an even number, and DC balance in the burst signal is ensured.

FIG. 5 shows an embodiment of the invention, in which the same circuits as in FIG. 1 are given the same reference numerals. A code error detection circuit 34 is included in the equalization amplifier circuit 19 and the control circuit 32, and a code error detection circuit 35 and a game alarm recovery circuit 36 are connected to the equalization amplifier circuit 26 and the control circuit 33. Code error detection circuit 3
"Niji line driver circuit 25 is on the output of 4?" ff controlled.

The down line from the city's 7th station station 11 to the subscriber's home 17 (C
The operation will be explained below. Code error 1 In the central output circuit 34, the width is 1lV (the received pulse signal from '+19 and the frame) the width is 1lV (the received pulse signal from '+19), the frame from VT32 is 1lV, and the width is 1lV.
Burst 1. using the t11 signal. It is determined whether the sum i-1 of "1" in number -i is an even number or an odd number, and the result of this determination is sent to the line driver circuit 25 on the transmitting side. If the determination result is an odd number, in the line driver circuit 11'l's 25, the polarity of the first bit in the next transmitted Haas l-=1M code (・'C is inverted 1, then \゛L A.M.
I '4" The 7J station output circuit 36 determines whether the polarity of the first bit is reversed for each burst signal on the uplink, whether it is 1 or 1. If a polarity reversal is detected, a downlink line abnormality is detected. The information is output to the downlink monitoring signal output terminal 37.

On the other hand, regarding the monitoring of the uplink from the subscriber's home 17 to the frost: word gap 11, the code error 1ψ output circuit 35 detects "1" in the burst signal in the same way as monitoring the downlink.
This is done by determining whether the sum of is even or odd. That is, if the number is odd, uplink line abnormality information is output to the uplink line supervisory output AhI1138.

As mentioned above, 1. ” Eri line 1 rough congratulation signal output terminal f3
By using the line monitoring signals of the upper and lower lines outputted to the upper and lower line monitoring signal output terminals 8 and 37, it is possible to centrally monitor the lines during communication at the central office side. Table 1 shows the rules for determining the line status of uplink and downlink lines using uplink burst signals. Table 1 shows that if the polarity of the first bit in the burst signal is positive, the lower 9 lines are guaranteed to be normal.

Table 1 Examples of monitoring using the judgment rules in Table 1 are shown below.
Since the line status monitoring shown in Figure 1 is a 1-bit error, the problem is how much the number of error bits is selected for the actual cycle time and sign. 1. Assuming that the code error generation process is random, the fault detection probability 1t can be calculated from equation (5) in IEICE Transactions 63-B, Vol. It gives me strength.

and X, ε is the actual bit error rate, εt is the threshold of the bit error rate, r is the transmission rate, and tM is the measurement time.

The calculation 15114 of the above equation is shown in FIG. FIG. 6 shows that the larger the number of code error bits nt is, that is, the longer the measurement time tM is, the more likely it is that failures will occur due to the reliability.

In this case, for example, r=64Kb/Sz nt-10, g
If t=1.0-5, oal * time tMid15
．． It will be 6 seconds. From FIG. 6, it can be said that with a reliability of 99%, the actual bit error rate at this time is 2.04.times.10' or less. In other words, according to the decision rule in Table 1, code errors in the upper and lower lines are counted every 16 seconds, and when 10 or more code errors are counted, an alarm is generated. It is possible to realize a monitoring system with a t1 error rate of approximately 2X]O""" at 99%.The numerical values of this 'A2i vision system, reliability, etc. are just examples, and the required monitoring system 7 system It can be decided according to the reliability of

<Effects> As described above, by using the present invention, the code error characteristics of the up and down lines during communication can be easily monitored with high precision using a circuit without adding any new bits. Therefore, without increasing the equipment price, line maintenance tests can be speeded up, and serviceability improvements that will be of great benefit to users will be promoted.

[Brief explanation of the drawing]

Figure 1 is a functional block diagram of the time division direction control transmission system, Figure 2 is a time chart explaining the operation of Figure 1, and Figure 3 is the burst diagram of Figure 2. Figure 4 is a time chart diagram explaining the role of the DC balance bit in Figure 3. Figure 5 is a block diagram of the equipment configuration showing the implementation of the present invention. It is a detection characteristic diagram. 1, 2, 23: Digital signal input terminal, 13°2
1, , 24.27: Speed conversion circuit, 14, 18:
Switch, 15, 25 line driver, 16: Balanced cable, 19.26: Equalization amplifier circuit, 22, 28: Digital signal output terminal, 31.32: Control circuit, 34, 3
5: Code error detection circuit, 36: Game alarm detection circuit, 37
: Downlink monitoring signal output terminal, 38: Uplink monitoring signal output terminal. Patent applicant Japanese type <@Telephone 1 phone public corporation representative (] 1! person Taku Kusano (11) A'71 Figure 12 Uka 2 Zuju 3 Figure piece 4 Fumi 5 Figure 1

Claims (1)

[Claims] (1) In a time-division direction control transmission method in which the transmitted signal and the received signal are time-compressed and bidirectional transmission is performed in each burst period, whether the number of positive and negative polarity pulses in the received signal within the burst period is equal. A time-division direction control transmission line characterized in that when it is detected that the number of pulses is unequal, the polarity of the first bit in the transmitted signal is completely inverted to transmit a game warning. Monitoring method