JP2001345788A - Monitoring device for communication channel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monitoring device capable of connecting in a type for branching to a TCM type communication line. SOLUTION: Frame synchronizing circuit 205 detects a synchronization of a down frame S21 input from a reception equalizer 203. An up/down phase decision circuit 214 decides timing of switching a transmission of the down frame and the up frame by using a detection result of the circuit 205, and switches a switch 202 based on the decision result. The monitoring device 130 is not connected in series with a communication line 140 by switching the up frame/down frame but can be connected in a branching type. Accordingly, the device 130 can prevent a change of conditions of the line 140 or a magnitude of a jitter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication line monitoring device for monitoring a frame transmitted in a communication line. The present invention relates to, for example, TCM (Time Comp
It is applied to the monitoring of communication lines that employ the "ression Multiplex" method.

[0002]

2. Description of the Related Art Conventionally, a TCM system has been known as a communication system. The TCM system is a communication system in which one communication path is time-divided to transmit both an upstream frame and a downstream frame, and is also called a ping-pong transmission system.

[0003] Conventionally, in a communication network,
A monitoring device may be used to monitor the state of a communication line.

FIG. 5 is a block diagram conceptually showing an example in which a conventional monitor device is connected to a TCM communication network. In FIG. 5, a network termination device 410 is connected to a subscriber terminal or the like (not shown),
Are connected to an exchange not shown. The monitor device 430 includes a network termination device 410 and a transmission line termination device 420.
And a frame sent from the network terminating device 410 to the transmission line terminating device 420 (hereinafter, referred to as an “up frame”) and a frame sent from the transmission line terminating device 420 to the network terminating device 410 (hereinafter, referred to as “frame”). Downstream frames).

FIG. 6 is a block diagram showing an example of the internal configuration of the monitor device 430.

In FIG. 6, a transmission line termination device 420
The received downstream frame is received by the termination unit 501 and
The waveform of the received frame S₅₁But
Will be played. PLL (Phase Locked Loop) circuit 503
Is the reproduced received frame S ₅₁The bit data that make up
The timing is extracted from the₅₂Output
I do. The frame synchronization circuit 504 receives the timing signal S₅₂
Using the received frame S ₅₁Of the received frame.
Room S₅₁To control bit S₅₃Is detected. Transmission circuit 50
5 is the received frame S₅₁And the timing signal S₅₂
Frame S₅₄As the end part 5
Send to 06. The terminating unit 506 is provided in the frame S₅₄The net
It transmits to the termination device 410.

On the other hand, the upstream frame transmitted by the network terminating device 410 is received by the terminating unit 506, and is received by the reception equalizing circuit 50.
At 7, the received frame _S55 is reproduced. PLL circuit 508
Extracts the timing from the bit data constituting the received frame S _55, and outputs a timing signal S _56. Frame synchronization circuit 509 performs synchronization detection of a received frame S ₅₅ by using a timing signal S _56, to detect the monitoring bits S ₅₇ from the reception frame S _55. The speed conversion circuit 510
The transmission timing of the received frame S _55, converts the timing of the timing signal S ₅₆ to the timing of the timing signal S _52. Transmission circuit 511 inputs the received frame S _55, in accordance with the timing of the timing signal S _52, and sends the terminal unit 501 as a frame S _58. Terminal part 501
Transmits the frame _S58 to the network terminating device 410.

[0008] Control / monitoring bit control circuit 512 inputs the control bits S ₅₃ from the frame synchronization circuit 504 inputs the monitored bits S ₅₇ from the frame synchronization circuit 509, to be displayed on a monitor device (not shown).

[0009]

As described above, the conventional monitoring device 430 disconnects the line between the network terminating device 410 and the transmission line terminating device 420 once, and places the line between the terminating devices 410 and 420. Had to connect. For this reason, it was not possible to monitor the state of the communication line under exactly the same conditions as when the network terminating device 410 and the transmission line terminating device 420 were directly connected.

When a monitor device 430 is provided between the terminating devices 410 and 420, the jitter of the transmission clock transmitted from the transmission line terminating device 420 to the network terminating device 410 is equivalent to the jitter generated in the device. Just get bigger. For this reason, the provision of the monitor device 430 also has a disadvantage that the reach of the frame is reduced.

In addition, since the monitor device 430 is provided between the terminating devices 410 and 420, the monitor device 430 may function as a repeater, and communication is possible when communication is actually impossible. There was a possibility that it would be.

For these reasons, there has been a demand for a monitor device which does not change the condition of the communication line or the magnitude of the jitter.

[0013]

A communication line monitoring apparatus according to the present invention detects first synchronization means for receiving an upstream frame and synchronization of the upstream frame received by the first reception means. A first frame synchronization unit for extracting predetermined data from these upstream frames, a second reception unit for receiving the downstream frame, and detecting synchronization of the downstream frame received by the second reception unit,
A second method for extracting predetermined data from these downstream frames
Frame synchronizing means, and an upstream frame or a downstream frame transmitted through a communication line are transmitted to a first receiving means or a second
A switch for supplying the signal to one of the receiving means, and an up / down phase determining means for switching the switch based on the input synchronization timing detected by at least one of the first frame synchronizing means and the second frame synchronizing means. ,
Display means for displaying data extracted by the first frame synchronization means and the second frame synchronization means.

A communication line monitoring device according to the present invention comprises:
Since the switch means and the up / down phase determination means are provided, the up frame can be received by the first receiving means and the down frame can be received by the second receiving means.
Thus, the communication line monitoring device of the present invention can be connected to such a communication line in a form that branches off from the communication line. For this reason, this communication line monitoring device
The condition of the communication line and the magnitude of the jitter are not changed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the size, shape and arrangement relationship of each component are only schematically shown to the extent that the present invention can be understood, and the numerical conditions described below are merely examples. .

FIG. 1 is a block diagram conceptually showing an example in which the monitor device according to this embodiment is connected to a TCM communication network. In FIG. 1, a network terminating device 110 is connected to a subscriber terminal or the like (not shown), and a transmission line terminating device 120 is connected to an exchange or the like (not shown).
Further, the monitor device 130 is connected in a form of branching from a communication line 140 connecting the network terminating device 110 and the transmission line terminating device 120, and a frame (up frame) sent from the network terminating device 110 to the transmission line terminating device 120 Also, a frame (downstream frame) sent from the transmission line terminating device 120 to the network terminating device 110 is monitored.

FIG. 2 is a block diagram showing the internal configuration of the monitor device 130.

As shown in FIG.
Is a termination unit 201, a switch 202, a reception equalization circuit 20
3. PLL circuit 204, frame synchronization circuit 205, speed conversion circuit 206, transmission circuit 207, reception equalization circuit 20
8, a PLL circuit 209, a frame synchronization circuit 210, a speed conversion circuit 211, a transmission circuit 212, a control / monitoring bit display circuit 213, and an up / down phase determination circuit 214.

The termination unit 201 receives an upstream frame and a downstream frame from the communication line 140 and
Send to 2.

The switch 202 switches circuits for inputting a downstream frame to the reception equalization circuit 203 and inputting an upstream frame to the reception equalization circuit 208.

The reception equalization circuit 203 receives a downstream frame from the termination unit 201, reproduces a waveform distorted during propagation on the communication line 140, and generates a digital signal. Reproduced digital signal, as a received frame S _21, output from the reception equalizer circuit 203.

The PLL circuit 204 extracts the timing from the bit data constituting the received frame S ₂₁ which is a digital reproduction, and outputs a timing signal S _22.

The frame synchronization circuit 205 performs synchronization detection of a received frame S ₂₁ by using a timing signal S _22, which detects a control bit S ₂₃ from the reception frame S _21. Also,
Frame synchronization circuit 205 is obtained by the synchronization detection, the detection timing of the downlink frame, and sends the uplink / downlink phase judging circuit 214 as a timing signal S _24.

The speed conversion circuit 206 receives the received frame S ₂₁
Is converted to the reception speed of a subsequent tester (not shown). The rate of conversion before the received frame S ₂₁ is obtained by the timing signal S _22. On the other hand, the speed of frame S ₂₉ after conversion, may be generated by dividing the timing signal S _22, may be generated using an oscillator or the like (not shown) generates otherwise Is also good.

The transmitting circuit 207 converts the format of the frame S ₂₉ inputted from the speed converting circuit 206,
Send to the subsequent tester. As the tester, for example, a commercially available I430 tester (a tester for detecting a bit error) can be used.

The reception equalization circuit 208 receives an upstream frame from the termination unit 201 and reproduces a digital signal. Reproduced digital signal, as a received frame S _25, output from the reception equalizer circuit 208.

The PLL circuit 209 extracts the timing from the bit data constituting the digitally reproduced received frame S ₂₅ and outputs a timing signal S ₂₆ .

The frame synchronization circuit 210 performs synchronization detection of a received frame S ₂₅ by using a timing signal S _26, to detect the monitoring bits S ₂₇ from the reception frame S _25. The reason why the frame synchronization circuit 210 for the upstream frame and the frame synchronization circuit 205 for the downstream frame are separately provided is that the patterns are different between the upstream frame and the downstream frame.

The speed conversion circuit 211 receives the received frame S ₂₅
Is converted into the reception speed of a tester (not shown) at the subsequent stage. Rate of the received frame S ₂₅ before conversion is obtained by the timing signal S _26. On the other hand, the converted frame S
Rate of _20, may be generated by dividing the timing signal S _26, may be generated using an oscillator, not shown, may be generated in other ways.

The transmitting circuit 212 converts the format of the frame S ₂₀ inputted from the speed converting circuit 211,
Send to the subsequent tester. As described above, for example, a commercially available I430 tester can be used as the tester.

The control / monitor bit display circuit 213 inputs the control bits S ₂₃ and monitoring bits S ₂₇ from the frame synchronization circuit 205, 210 to be displayed on a monitor device (not shown).

The upstream / downstream phase determination circuit 214 determines the downstream frame transmission timing and the upstream frame transmission timing in the communication line 140 using the timing signal S ₂₄ input from the frame synchronization circuit 205, and determines the determination result. It is used to generate a signal S ₂₈ for switching the switch 202. The transmission timing of the upstream frame in the communication line 140 is controlled depending on the transmission timing of the downstream frame. Therefore, it is possible to determine the transmission timing of the downstream frame and the upstream frame based only on the transmission timing of the downstream frame.

FIG. 3 is a timing chart for explaining the operation principle of the up / down phase determination circuit 214.

As shown in FIG. 3, the lengths of the downstream frame and the upstream frame are both 377T. The distance between the first bit of the downstream frame and the first bit of the next downstream frame is fixed to 800T. The minimum distance between the last bit of the downstream frame and the first bit of the next upstream frame is 6T. Furthermore, the gap between the last bit of the up frame and the first bit of the next down frame is
The maximum is 40T. The first 8 bits of the downstream frame are a time slot of a frame synchronization cycle. The first 8 bits of the downstream frame are '100000M0'. here,
“M” is a bit that alternates with “1” and “0” for each downlink frame. By detecting this specific pattern, a downstream frame can be detected. '1000
When the pattern of 00M0 ′ is detected, the remaining length of the downstream frame is 369T. Therefore, the length up to the first bit of the upstream frame is at least 375T (369T).
+ 6T), the minimum length of the upstream frame to the last bit is 752T (375T + 377T), and
The length up to the first bit of the next downstream frame is 792T
(752T + 40T). That is, the transmission timing of the downstream frame and the upstream frame can be determined based on the timing at which “100000M0”, which is the head of the downstream frame, is detected. Up /
The down phase determination circuit 214 switches the switch 202 to the reception equalization circuit 208 side from the transmission of the last bit of the down frame to the transmission of the first bit of the up frame (t _{2 in} FIG. 3), and Between the transmission of the last bit of the upstream frame and the transmission of the first bit of the downstream frame,
Side (t _{3 in} FIG. ₃ ). In the example shown in FIG.
The switch 202 is switched 4T and 421T after the last bit of the downstream frame is transmitted.

In this case, the switching timing of the switch 202 is determined based on the downstream frame. However, the switching timing may be determined based on the upstream frame. Of course, it is also possible to make a determination based on both. Note that the first 8 bits of the upstream frame are always "100000M". Here, “M” is a bit that alternates with “1” and “0” for each uplink frame.
Bits are used. Therefore, the detection timing of the leading 8 bits can be used for the determination of the switching timing of the switch 202.

As described above, in this embodiment, since the switch 202 can be switched by detecting the transmission timing of the downstream frame and the upstream frame, it is possible to connect the monitor device 130 by branching off from the communication line 140. Will be possible. Therefore, the monitor device according to this embodiment does not change the condition of the communication line 140 or the magnitude of the jitter.

[0037]

As described above in detail, according to the present invention, it is possible to provide a monitor device which does not change the condition of the communication line or the magnitude of the jitter.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a connection relationship of a monitor device according to an embodiment.

FIG. 2 is a block diagram showing an internal configuration of the monitor device according to the embodiment.

FIG. 3 is a timing chart for explaining an operation of the monitor device according to the embodiment;

FIG. 4 is a block diagram showing an internal configuration of a monitor device according to a modification of the embodiment.

FIG. 5 is a block diagram showing a connection relationship of a conventional monitor device.

FIG. 6 is a block diagram showing an example of an internal configuration of a conventional monitor device.

[Explanation of symbols]

 Reference Signs List 110 network termination device 120 transmission line termination device 130 monitoring device 201 termination unit 202 switch 203, 208 reception equalization circuit 204, 209 PLL circuit 205, 210 frame synchronization circuit 206, 211 speed conversion circuit 207, 212 transmission circuit 213 control / monitoring Bit display circuit 214 Up / down phase determination circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K018 AA01 BA03 CA11 EA01 FA04 FA07 HA01 5K028 AA03 AA14 BB02 CC02 DD06 KK23 LL13 NN45 RR02 5K042 AA08 BA10 CA05 DA16 EA15 FA03 JA01 LA09 5K047 AA11 BB05 MM05HMMH

Claims (2)

[Claims] A first receiving means for receiving an upstream frame; a first receiving means for detecting synchronization of the upstream frame received by the first receiving means and extracting predetermined data from the upstream frame; Frame synchronization means, second reception means for receiving downlink frames, and second synchronization means for detecting synchronization of the downlink frames received by the second reception means and extracting predetermined data from these downlink frames. A frame synchronization unit, a switch for supplying the upstream frame or the downstream frame transmitted through a communication line to one of the first reception unit or the second reception unit, and a first frame synchronization unit or Based on the synchronization timing detected by at least one of the second frame synchronization means, an up / down phase determination for switching the switch is performed. Means and said first frame synchronization means and said second frame synchronization means monitoring device for a communication line, characterized in that it comprises a display means for displaying the extracted data. 2. A first transmitting means for transmitting the upstream frame received by the first receiving means to an external tester or a first transmitting means for transmitting the downstream frame received by the second receiving means to an external tester. 2. The communication line monitoring device according to claim 1, further comprising at least one of the two transmission units.