JPH05110632A - Communication line test circuit - Google Patents

Abstract

PURPOSE:To test a communication line even when a voice use high efficient coding decoding device or the like where the relation between a sent test pattern and a received test pattern are not definitely defined on the way of the communication line. CONSTITUTION:The propriety of a communication is decided by calculating the S/N based on a test pattern sent from a test circuit 8 to the communication line 1 and a test pattern received from the communication line and comparing the threshold level in response to the difference between loopback points (1), (2) with the calculated S/N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication line test circuit in a digital communication switching system.

[0002]

2. Description of the Related Art FIG. 3 is an explanatory diagram of a conventional test method in a digital communication circuit.

In FIG. 3, the digital communication line 1,
When a communication line system is configured by the communication path 2 and the transmission devices 3a and 3b and this communication line system is tested, the test pattern sending circuit 4a sends a test pattern composed of a digital bit pattern, and a turn-around point or The test pattern is folded back in, the receiving circuit 5 receives the folded back test pattern, and the comparison circuit 6 collates the received test pattern with the transmitted test pattern,
The quality of the communication line system is determined according to the comparison result. In this conventional test method, when each device on the communication line 1 is operating correctly, when the transmission device 3a, 3b loops back to form a loop, the transmitted test pattern and the received test pattern It is assumed that and match exactly.

[0004]

However, an apparatus for performing a non-linear process in which the relationship between the test pattern transmitted to the loopback loop and the test pattern received from the loopback loop is not uniquely determined (for example, for voice When the efficient coding / decoding device) is inserted into the communication line 1,
Even if each device on the communication line 1 is operating correctly,
The test pattern sent does not match the test pattern received. Therefore, in the conventional method, if a high-efficiency voice coding / decoding device or the like is inserted in the middle of the communication line 1, it is impossible to judge the quality of the communication line system.

According to the present invention, even if a high-efficiency voice coding / decoding device or the like for which the relationship between the transmitted test pattern and the received test pattern is not uniquely determined is connected in the middle of the communication line, It is an object of the present invention to provide a communication line test circuit capable of testing a communication line.

[0006]

According to the present invention, the S / N ratio is calculated based on the test pattern sent to the communication line and the test pattern received from the communication line, and the S / N ratio is determined according to the difference of the return points. The quality of the communication line is determined by comparing the threshold value with the calculated S / N ratio.

[0007]

According to the present invention, the S / N ratio is calculated based on the test pattern sent to the communication line and the test pattern received from the communication line, and the calculated S / N ratio is calculated as the threshold value according to the difference of the turnaround points. Since the quality of the communication line is determined by comparing with the / N ratio, a highly efficient coding / decoding device for voice in which the relationship between the transmitted test pattern and the received test pattern is not uniquely determined. Even if is connected in the middle of the communication line, the communication line can be tested.

[0008]

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

This embodiment is an example of a digital mobile communication system in which a high-efficiency CODEC device 4 is connected to a digital communication line 1, in which a communication path 2 and a radio base station 3 are connected to the digital communication line 1 The base station 3 and the mobile device 7 communicate with each other, and a test circuit 8 is provided at the end of the communication path 2.

FIG. 2 is a block diagram showing a concrete example of the test circuit 8 in the above embodiment. The test circuit 8 includes a test pattern storage unit 81, a transmission circuit 82, a reception circuit 83, a reception signal storage unit 84, and a control circuit 85.

The test pattern storage unit 81 is an example of a test pattern storage unit that stores a predetermined test pattern composed of digital bit patterns, and is a transmission circuit 82.
Is a signal sending means for sending the test pattern stored in the test pattern storage means to the digital communication line, and the receiving circuit 83 returns the test pattern sent from the signal sending means to the digital communication line at a predetermined turning point. The received signal accumulating unit 84 is an example of a received signal accumulating unit that accumulates the received signal received by the signal receiving unit. Control circuit 85
Is an example of the S / N ratio calculating means for calculating the S / N ratio based on the signal strength represented by the test pattern transmitted from the signal transmitting means and the signal strength represented by the signal pattern received by the signal receiving means, Further, an example of the line quality determination means for determining the quality of the digital communication line by comparing the S / N ratio calculated by the S / N ratio calculation means with a threshold value according to the state from the signal transmission means to the turning point. But also.

Next, the operation of the above embodiment will be described.

In mobile communication, narrow band transmission of voice information is performed in order to effectively use radio frequencies. In other words, the voice signal encoded by the mobile device 7 with high efficiency is high efficiency C.
Normal 64 kbps μ-law in ODEC device 4
After being converted into a voice signal, it is exchanged and connected by the communication path 2. On the other hand, in the opposite direction,
The 4 kbps μ-law voice signal is converted into a high-efficiency signal by the high-efficiency CODEC device 4, and is transmitted to the mobile device 7 via the wireless base station 3.

In this case, even if the high-efficiency CODEC device 4 is operating normally, the digital bit patterns before and after the high-efficiency CODEC device 4 do not uniquely correspond to each other, and therefore the transmitted test pattern and the received test pattern are not included. It cannot be determined that the communication line 1 is abnormal because the test circuit 8 cannot match the above. In the above embodiment, after the signal is turned back at the turning point or at the turning point, the received μ-
The S / N ratio of the raw signal is measured.

That is, in the test circuit 8, the control circuit 8
The reference numeral 5 retrieves a predetermined test pattern from the test pattern storage unit 81 based on a test control signal from the outside, and sends the retrieved test pattern to the digital communication line 1 via the transmission circuit 82. Then, the receiving circuit 83 receives the test pattern folded at or from the turning point.
Is received, and the received signal storage unit 84 stores the received test pattern. On the other hand, the control circuit 85 compares the transmitted test pattern with the received test pattern, finds a point (corresponding point) that correlates at the voice level, and a test pattern is obtained for each sample point at this matching point. The difference between the signal intensities represented is calculated. That is, the difference between the signal strength at a predetermined sample point of the transmitted test pattern and the signal strength at the same sample point of the received test pattern is calculated, and the difference is grasped as a noise value, and the transmitted test pattern is calculated. The value of the noise with respect to the signal intensity represented by is the S / N ratio to be obtained. The operation of converting the test pattern into the signal strength and the operation of calculating the S / N ratio are actually executed by a computer, but the operation of the S / N ratio can be executed by a so-called analog circuit. ..

The S / N ratio calculated in this way is compared with a preset threshold value, and the result is notified to the outside by a test control signal. In addition, communication path 2, high efficiency COED
C4, when the radio base station 3 is normal, the S / N ratio of the received test pattern is measured in advance, and the measured S
Based on the / N ratio, an S / N ratio necessary for determining that the communication line 1 is abnormal is assumed, and the assumed S / N ratio is the preset threshold value.

In the above embodiment, the threshold value of the S / N ratio is selected according to the turning point. That is, in general,
Since the turning point is the turning point in the wireless line section, the signal deterioration is larger than that in the turning point at the turning point. Therefore, when determining the S / N ratio in the test circuit 8, it is necessary to set the threshold values to be preset to different values depending on the difference of the folding points. When the system of the digital communication line 1 is composed of only the transmission line and the digital processing is not performed, the threshold value to be set in advance is set to, for example, 20 dB, and when it is larger than 20 dB, it is determined that the communication line 1 is normal. However, when the high-efficiency CODEC device 4 performs coding / decoding and includes a wireless line such as between the wireless base station 3 and the mobile device 7 and is folded back at this end, the above-mentioned preset is set. The threshold to be set is, for example, 0 dB, and when it is larger than 0 dB, it is determined that the communication line 1 is normal. As described above, since the threshold value of the S / N ratio can be changed corresponding to the turning point, the test of the digital communication line including the wireless section can be performed on the same line.

Further, in the above embodiment, the test pattern to be transmitted is selected according to the turning point. That is, the PCM code 8-bit voice pattern is transmitted to the digital communication line in the normal case, but is transmitted to the digital communication line at a low bit rate (for example, the PCM code 2-bit voice pattern) in other cases. Moreover, since the bit rate when transmitting to the digital communication line is different, the test pattern to be transmitted is selected according to the bit rate and the like. In the above embodiment, the control circuit 85 presets the threshold value and the test pattern based on the instruction of the test control signal.

In the above embodiment, the system of the digital communication line 1 is composed of only the transmission line, and the digital communication line 1 can be tested even when the digital processing is not performed. It is also possible to test a line (a communication line in which a device performing nonlinear processing such as a high-efficiency coding / decoding device for voice is not inserted).

[0020]

According to the present invention, the signal returned from the digital communication line is compared with the original signal to obtain the S / N ratio, and the quality of the line is judged based on this S / N ratio. Therefore, it is possible to test a digital communication line in which a high-efficiency coding device or the like is inserted.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a specific example of a test circuit 8 in the above embodiment.

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Digital communication line, 2 ... Communication path, 3 ... Radio base, 4 ... High efficiency CODEC device, 7 ... Mobile device, 8 ... Test circuit, 81 ... Test pattern storage part, 82 ... Transmission circuit, 83 ... Reception circuit, 84 ... Received signal storage unit, 85 ... Control circuit.

Claims (1)

[Claims] 1. A communication line test circuit in a digital telecommunication switching system, comprising: a signal sending means for sending a predetermined test pattern composed of a digital bit pattern to the digital communication line; and the signal sending means to the digital communication line. Signal receiving means for receiving a signal in which the transmitted test pattern is turned back at a predetermined turning point; received signal storage means for storing the received signal received by the signal receiving means;
An S / N ratio for calculating an S / N ratio based on the signal strength represented by the test pattern transmitted from the signal transmitting means and the signal strength represented by the signal pattern received by the signal receiving means.
Ratio calculating means; S / N calculated by this S / N ratio calculating means
A communication line test circuit, comprising: a line quality judgment unit for judging the quality of the digital communication line by comparing the ratio with a threshold value according to the state from the signal transmission unit to the turning point. ..