JP2981637B2 - Line test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line test apparatus for testing, for example, a dedicated line connecting high-speed modems.

[0002]

2. Description of the Related Art In a dedicated line that does not pass through an exchange, FIG.
As shown in (1), extremely high-speed and secure data communication can be performed between the terminals 4 and 5 via the high-speed modem devices 2 and 3 connected to both ends of the line 1. Therefore, when it is necessary to surely transmit a large amount of data to a predetermined partner, this dedicated line is used.

[0003] This kind of dedicated line passes through a telephone station 6, and maintenance of the line is performed by a line test from the telephone station side. The line test uses the loopback function of the modem device on the line under test so that the line test can be performed even when the terminal of the line is not movable.

[0004] That is, when receiving a specific activation code from the line 1, the modem devices 2 and 3 used for this type of line do not transmit signals from the line side to the terminals 4 and 5 but transmit the signals to the line side. It has a function of releasing this folded state when it is sent back and receives a specific release code.

Therefore, the conventional test apparatus 10 for testing this kind of line outputs the specific activation code and release code as shown in FIG. 8 to return the modem device on the line under test to the loopback. A control code sending unit 11 for controlling functions is provided together with the measuring unit 12.

When actually performing a line test, the dedicated line is disconnected in the station, and the control code transmitting unit 1 is transmitted to the modem 2 on the line under test via the modem 7 in the station.
1 sends the activation code. After outputting the activation code, the measurement unit 12 automatically (or manually) measures the transmission characteristics of the line. When the measurement is completed, a release code is output from the control code sending unit 11. Finally, the line disconnection point is connected, and the test on the line from the station 6 to the modem device 2 is completed.

[0007]

However, in the conventional line test apparatus 10 as described above, immediately after the activation code is output from the control code transmission unit 11, the measurement unit 1
2, the measurement is performed even when the loopback function is not activated due to, for example, an abnormality in the modem device 2. This abnormality appears as an abnormality in the measurement result of the measuring unit 12, but if the operator does not constantly check the progress of the measurement during the measurement, the abnormality cannot be found and unnecessary measurement will be performed.

In a conventional test apparatus, a modem device 2
Since the loopback function is correctly activated and the test is terminated by sending a release code after the measurement is completed,
If the loopback function is not correctly released due to an abnormality in the modem device 2, the test is completed while the line is in a loopback state, causing a great deal of damage to the line user. In particular, the release failure of the loopback function is a serious problem that cannot be found even if the line test apparatus having the conventional configuration performs the test many times. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problem and to provide a line test apparatus capable of reliably confirming activation and release of a loopback function of a modem device on a line under test.

[0009]

In order to solve the above-mentioned problems, a line test apparatus according to the present invention is configured such that one end is connected to a modem device which receives a specific activation code or release code and activates or releases a loopback function. And a control code transmitting means (21, 35) for transmitting the specific activation code or release code to the circuit under test; and a control code transmitting means for transmitting the activation code by the control code transmitting means. Or a pattern sending means (23, 35) for sending a predetermined pseudo-random pattern signal to the circuit under test every time a release code is sent; and sending a pseudo-random pattern signal from the pattern sending means to the circuit under test. While the return signal from the circuit under test is received, and the synchronization between the received signal and the pseudo-random pattern is synchronized. Pattern synchronization detecting means (27, 35) for detecting whether or not synchronization is established, and determining whether or not to activate or release the loopback state of the line under test based on whether or not the pattern synchronization detecting means has established synchronization. Means (35).

[0010]

With this configuration, in the line test apparatus of the present invention, when the activation code or the release code is transmitted to the line under test, a pseudo-random pattern signal is transmitted subsequently, and the pseudo-random pattern signal is transmitted. Synchronization detection is performed.
When the synchronization after the output of the activation code is determined, it can be confirmed that the line is in the loopback state, and when the synchronization after the output of the release code is not determined, it can be confirmed that the loopback state has been released.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a line test apparatus 20 according to an embodiment provided in a telephone station 6. The line test apparatus 20 is connected at both ends to the modem apparatus 2 and performs error measurement on the 4-wire dedicated lines 1a and 1b passing through the telephone station 6. A connection between a desired dedicated line from a large number of dedicated lines and the test apparatus 20 is established through the modem device 7 in advance.

The control code generator 21 of the line test apparatus 20
Receives a control signal from the control unit 35, which will be described later, and transmits a specific activation code A and a release code B for activating or releasing the loopback function of the modem device 2 on the line terminal side via the transmission switch 22. Send it to the modem device 7.

A pattern generator 23 transmits a pseudo-random pattern signal to the modem device 7 via a transmission switch 22.
Send to The pattern generator 23 is, for example, as shown in FIG. 2, to connect the flip-flop 24 _{1-24 9} 9 stages in cascade, the last stage 9 of the output and the fifth stage and the output EX-OR circuit type 25, configured to input its output to the first stage, from 9-stage flip-flop 24 _9, in synchronization with 9 bits to 511 or pseudo-random pattern of the clock signal by one bit of different as one pattern Output.

The pattern synchronization detector 27 is connected to the modem device 7 via the reception switch 26.
To to indicate that configuration, after the 9-bit pattern signal is input to the beginning via the input switch 28, and stored as an initial pattern to each flip-flop 29 _{1-29 9} of 9 stages connected in cascade, the input EX-O switch 28
Switch to the output side of R circuit 30. The EX-OR circuit 30, the output of flip-flop _295, 29 ₉ of the fifth stage in exactly the same manner as the pattern generator 23 and the ninth stage is input, the initial value for the flip-flop 29 _{1-29 9} Is the same as the pattern output from the pattern generator 23, the pattern output from the EX-OR circuit 30 after the input switch 28 is switched is
Will be synchronized with the pattern. EX-OR circuit 30
And the input signal are compared bit by bit by a comparator 31, and the comparison result is output to a synchronization detection control unit 32.

Upon receiving the detection start signal S from the control unit 35, the synchronization detection control unit 32 connects the switch 28 to the input signal side, and stores 9-bit data into the flip-flop 2.
9 After Mase read in _{1-29 9,} the input switch 28 EX
-Switch to the OR circuit 30 side. Then, for example, when no error occurs in the comparator 31 for 9 consecutive bits, it is determined that synchronization with the input signal has been determined, and a synchronization determination signal is sent to the control unit 35. Performs an error detection by reading the initial value again.

The line test apparatus continuously outputs a pattern signal from the pattern generator 23 to the line even after the synchronization is determined, and the control unit 35 counts the number of error signals of the comparator 31 for the transmission pattern. Then, error measurement for the line is performed, and the measurement result is displayed.

The control unit 35 controls the above-described units in accordance with the flowchart shown in FIG. 4 to display the status of activation and release of the loopback function of the modem device 2 and the measurement results and the like.
6 is displayed. Hereinafter, the operation of the line test apparatus 20 will be described with reference to the flowchart of FIG.

First, the transmission changeover switch 22 is connected to the P1 side, that is, the control code generator 21 side, and a control signal for causing the control code generator 21 to transmit a specific activation code A is output (S1). , S2).

The activation code A output from the control code generator 21 is sent to the line 1a via the modem device 7,
It is received by the modem device 2 on the terminal side. If there is no abnormality in the line 1a and the modem device 2, the loopback function in the modem device 2 is activated, and the lines 1a and 1b are connected in a loopback state.

Next, the transmission switch 22 is switched to the P2 side, that is, to the pattern generator 23 side, the reception switch 26 is switched to the pattern synchronization detector 27 side, and the detection start signal S is sent to the pattern synchronization detector 27. It is output (S3, S4).

By this switching, the pattern signal of the pattern generator 23 is transmitted to the line 1 via the modem device 7.
a, and a return signal to the line 1b is output to the pattern synchronization detector 27 via the modem device 7.

Here, for example, the initial bit pattern of the pattern generator 23 is as shown in FIG.
(A ₀ , b ₀ ,..., H ₀ , i ₀ ), this pattern is output to the line 1a in order from a _0, and after 9 bits are output, as shown in FIG. It becomes a pattern (a ₁ , b ₁ ,..., H ₁ , i ₁ ).

If there is no abnormality in the line 1a and the modem device 2, the pattern up to the first 9 bits (a _{0 to} i ₀ )
Are initially set in the flip-flops 29 _{1 to} 29 ₉ of the pattern synchronization detector 27 as shown in FIG.
The first bit of the next pattern, that is, a ₁ is output from the R circuit 30. Since the pattern generator 23 and the pattern synchronization detector 27 operate on the same clock, when the line is in a normal loopback state, the input signal and EX
-The output of the OR circuit 30 continuously matches, and a synchronization determination signal is output.

If there is an abnormality in the line 1a or the modem device 2 and the loopback function has not been started normally, a signal irrelevant to the output pattern of the pattern generator 23 is sent to the pattern synchronization detector 27. (For example, all “0” or “1” signals) are input,
Synchronization is not fixed.

When receiving the synchronization confirmation signal within a predetermined time, the control unit 35 outputs a character indicating that the dedicated lines 1a and 1b are in a normal loopback state (for example, "start confirmation O").
K ”) is displayed on the display device 36 (S5, S6).

If the synchronization determination signal is not received within a predetermined time, a character (for example, "startup confirmation NG") indicating that there is an abnormality in the dedicated line or the modem device 2 is displayed on the display device 36 (S7). ).

When it is determined that the line has returned to the normal loopback state, error measurement for the line is started, and a character indicating that measurement is being performed (such as "measuring") is displayed. Upon completion, the measurement result (error rate) is displayed on the display device 36 (S8 to S11).

Next, the transmission changeover switch 22 is connected to the control code generator 21 side, and the release code B is transmitted from the control code generator 21 (S12, S13). This release code B is sent to the line 1a via the modem device 7 and received by the modem device 2 on the terminal side. If the modem device 2 that has received the release code B is normal, the return state of the dedicated line is released. If the modem device 2 has an abnormal reception of the release code B, the return state of the dedicated line is not released. Will remain.

After transmitting the release code B, the control unit 35
The transmission switch 22 is connected to the pattern generator 23 again, and the reception switch 26 is connected to the pattern synchronization detector 27.
And outputs the detection start signal S (S14, S14).
15).

If the return function of the modem 2 has been correctly released, the pattern generator 23 outputs
Since the pattern signal sent to the side is not looped back to the line 1b side, the synchronization is not determined in the pattern synchronization detector 27, and if the loop-back function of the modem device 2 is not released, a predetermined time Synchronization is confirmed within.

When the synchronization is not determined, the control unit 35 displays a character (for example, “release confirmation OK”) indicating that the loopback state of the leased line has been correctly released.
And if the synchronization is confirmed, a character indicating that the loopback state of the leased line has not been released (for example,
"Release confirmation NG" or the like is displayed on the display device 36 (S
16-S18).

As described above, the confirmation of the line state after the output of the activation code A and the confirmation of the line state after the output of the release code B are performed by detecting the synchronization of the pattern. Measurement is not required, and
Since it is possible to reliably detect the release failure of the loopback state of the line,
Damage to the line user due to this failure can be extremely reduced.

In the above embodiment, the pattern generator 2
3 and the pattern synchronization detector 27 are used for both confirmation of the line state after the output of the activation code and after the release code is output and for error measurement, and the error measurement is automatically started after the synchronization of the line is determined. However, the present invention can also be applied to a line test apparatus that performs measurement by manually operating a separate measurement unit. In this case, the measurement may be performed by manually connecting the measurement unit to the line after the start-up confirmation, and a signal notifying the end of the measurement may be manually input to the control unit 35.

In the above-described embodiment, the line state is checked only once. However, if the activation or release of the loopback state is not correctly performed, the activation including the output of the activation code and the release code is performed. Confirmation process (S1 to S in FIG. 4)
5) and the release confirmation process (S12 to S16 in FIG. 4) may be performed a plurality of times consecutively before the determination.

In the above-described embodiment, the case where the control unit 35 controls one test apparatus has been described. However, the control unit 35 provided at the center transmits the test apparatus in a plurality of telephone stations in the same manner as described above. May be controlled via another line.

In the above embodiment, the case where the high-speed 4-wire dedicated line not passing through the exchange is used as the line under test has been described. However, this is not limited to the present invention, and the present invention is not limited thereto. The present invention can be similarly applied to a device for testing a line to which a modem device having a function is connected.

[0037]

As described above, the line test apparatus of the present invention outputs a pseudo code every time a specific code for starting or releasing the loopback function of the modem device connected to one end of the line under test is output. The random pattern signal is transmitted to the line under test, and the start-up or release confirmation of the loop-back state of the line is performed by detecting the synchronization of the pattern of the loop-back signal from the line.

Therefore, even when performing an automated measurement, it is not necessary to perform useless measurement on the circuit under test, and it is not necessary to know that the loopback state has not been released. It is possible to prevent the termination of the test, and to minimize the damage to the line user.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing details of a main part of one embodiment.

FIG. 3 is a block diagram showing details of a main part of one embodiment.

FIG. 4 is a flowchart illustrating a processing procedure of a main part of one embodiment.

FIG. 5 is a pattern diagram in a pattern generator of one embodiment.

FIG. 6 is a pattern diagram in a pattern synchronization detector of one embodiment.

FIG. 7 is an explanatory diagram of a dedicated line.

FIG. 8 is a block diagram of a conventional device.

[Explanation of symbols]

 1a, 1b Dedicated line 2 Modem device 4 Terminal 6 Telephone office 7 Modem device 8 Access device 20 Line test device 21 Control code generator 22 Transmission switch 23 Pattern generator 26 Receive switch 27 Pattern synchronization detector 35 Control unit 36 Display device

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Hiraike 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Isao Tanaka 4-7-17 Kamata, Ota-ku, Tokyo Ando (56) References JP-A-1-157650 (JP, A) JP-A-62-276941 (JP, A) JP-A-1-256249 (JP, A) JP-A-3-42945 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H04L 29/14

Claims (1)

(57) [Claims] 1. A line test apparatus for receiving a specific activation code or release code and testing a line under test having one end connected to a modem apparatus for activating or releasing a loopback function, wherein the specific activation code or the release code is A control code transmitting means (21, 35) for transmitting a release code to the circuit under test; and each time the activation code or the release code is transmitted by the control code transmitting means, a predetermined pseudo-random pattern signal is transmitted to the circuit under test. Pattern sending means (23, 35) for sending to a line, and while the pattern sending means sends a pseudo-random pattern signal to the line under test, a return signal from the line under test is received. Pattern synchronization detecting means (27, 35) for detecting whether or not the synchronization with the pseudo random pattern has been determined; Depending on the presence or absence of the synchronization of the pattern synchronization detection means,
A line test apparatus comprising: a determination unit (35) for determining whether to start or release the loopback state of the line under test.