JPS6313577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a line quality monitoring device that monitors the line quality of a communication line, and in particular, the present invention relates to a line quality monitoring device that monitors the quality of a communication line. The present invention relates to a line quality monitoring device for monitoring.

A conventional line quality monitoring device of this type has a configuration as shown in FIG. The operation will be explained with reference to FIG. 2 which shows the time chart of the signals of each part. When the sine wave signal a output from the sine wave oscillator 2 passes through the communication line 1, which is the line to be monitored, the amplitude increases due to line noise. and is input to the rectifier circuit 3 after receiving phase distortion. The rectifier circuit 3 rectifies the distorted sine wave signal b and outputs a line signal c.

On the other hand, if the end of another communication line 1' in the same transmission path is terminated with a terminator 6, only the line noise d is input to the rectifier circuit 3'. In the rectifier circuit 3', line noise d
is rectified and a noise level signal e is output.

The subtraction circuit 4 subtracts the noise level signal e from the line level signal c and outputs the resulting signal as a quality level signal f corresponding to the line quality. The comparison circuit 5 determines whether the quality level signal f is above a certain standard or not, and outputs a line quality standard deterioration signal g when it is below the standard. (L+ section) The above configuration is widely used because the circuit configuration is simple and the monitoring accuracy is high.
It requires a line and cannot be used when only one monitored line is available.

If only one line to be monitored is available, the sine wave signal, which is distorted due to line noise when passing through the above one line, can be passed through a bandpass waver and a bandstop waver in the same frequency band. A method has been proposed in which the distorted sine wave signal b and line noise d in FIG. 1 are separated into approximate sine wave signals and line noise, and the same operation as in the case of FIG. 1 is performed. A method has also been proposed in which only the line noise d is monitored and the line level signal c in FIG. 1 is stipulated to be constant at all times.

However, the former method, in which the line to be monitored is treated as one line, requires a band-pass waver and a band-elimination waver, so the monitoring accuracy is determined by the accuracy of the waver. The latter method, which does not use a device, has the disadvantage that monitoring accuracy cannot be guaranteed except when the line level signal is always constant and the noise level varies.

The present invention provides a transmission line accommodating a large number of lines,
For example, in a micro line transmission line, it is best to representatively monitor the quality of each line by checking the quality of a specific line within the transmission line. The present invention provides a line quality monitoring device that can monitor line quality based on the relative relationship between noise level and noise level.

In order to achieve the above object, the present invention does not simply use a sine wave that has been distorted by line noise as a line level signal, but also uses a sine wave that has been distorted so that it can be used as a noise level signal at the same time. The shaped signal sliced and shaped at a predetermined level is compared with a reference waveform signal having the same frequency of a sine wave synchronized with this shaped signal, and the comparison result signal is converted into a sampling signal having a frequency that is an arbitrary integer multiple of the sine wave signal. Element errors are detected by sampling, and the quality of the communication line is monitored based on whether the number of element errors within a predetermined monitoring time exceeds a reference value.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram showing an embodiment of the present invention;
Figure 4 is a time chart of each part. When the sine wave signal a output from the sine wave oscillator 2 passes through the communication line 1 which is the line to be monitored, it is input to the waveform shaping circuit 7 after being subjected to amplitude and phase distortion due to noise in the communication line. The waveform shaping circuit 7 generates a waveform shaping signal h which rises and falls from the distorted sine wave signal b at a predetermined rising side (+ side) slice level S+ and falling side (- side) slice level S-.
is generated and input to the exclusive OR circuit 8.

On the other hand, the rectangular wave oscillator 11 is a reference waveform signal whose phase is controlled using, for example, the rising edge of the rectangular wave signal h obtained by the waveform shaping circuit 7 as a synchronization detection point B, and which is a rectangular wave having the same frequency as the sine wave oscillator 2. generate i.

Here, the phase control in the square wave oscillator 11 is 1
The phase control is performed every cycle, and if there is no synchronization detection point, the phase control is not performed. However, the phase control is not limited to this, and the phase control may be performed in any cycle.

A reference sampling signal k synchronized with the reference waveform signal i is converted by a multiplier circuit 12 into a sampling signal l having a frequency three times that of the sine wave signal a, for example, in accordance with an arbitrary code transmission rate.

The exclusive OR circuit 8 compares the waveform shaped signal h with the reference waveform signal i, and the AND circuit 9 compares the comparison result signal j with the sampling signal l to detect an element error m.

Element errors m are counted by a preset counting circuit 10. The sampled signal l is supplied to the sample counting circuit 13
and depending on the predetermined monitoring time, e.g. 18
The reference drop signal o is reset by outputting a reset signal n to the preset counting circuit 10 once for each sampled signal l. Next, the preset counting circuit 13 starts counting again and calculates the preset value,
For example, if the number exceeds 2, the reference decrease signal o is output.

According to the above embodiment, the preset value of the element error is set to 2 at a code transmission rate three times that of the sine wave signal, and the monitoring time is 18 times the known time interval of the sampling signal l.
It is possible to monitor the quality of the line for each SN.

Furthermore, according to the present invention, when the distorted sine wave signal b is waveform-shaped and does not reach the slice level on the rising side (+ side) or the falling side (- side), the waveform-shaped signal h is Since the state is maintained (section A), element errors can be detected even when the communication line 1 is disconnected (section C of signal j in FIG. 4).

As explained above, the present invention uses only one line to be monitored, and without using a band-pass waver or a band-stop waver as in the past, the line quality is determined based on the relative relationship between the signal level and the noise level. It has the remarkable effect of being able to monitor the quality of the product with high precision using a simple circuit configuration.

[Brief explanation of the drawing]

1 and 2 are block diagrams of a conventional line quality monitoring device and time charts of signals of each part of the device, and FIGS. 3 and 4 are block diagrams of a line quality monitoring device according to an embodiment of the present invention. and a time chart of the signals of each part of the device. 1, 1'...Communication line, 2...Sine wave oscillator, 3,
3'... Rectifier circuit, 4... Subtraction circuit, 5... Comparison circuit,
6... Terminator, 7... Waveform shaping circuit, 8... Exclusive OR circuit, 9... AND circuit, 10... Preset counting circuit, 11... Square wave oscillator, 12... Multiplier circuit, 1
3...Sample counting circuit.

Claims (1)

[Claims] 1 means for sending a sine wave signal to a communication line; means for generating a shaped signal by slicing and shaping the sine wave signal distorted by the communication line at a predetermined level; means for generating a reference signal having the same frequency as the signal; means for comparing the reference signal and the shaped signal to extract signal components that do not match; and a sample having a desired frequency that is an integral multiple of the sine wave signal. means for generating a sampled signal with variable frequency; means for detecting element errors by logically multiplying the sampled signal and the signal component; and means for counting the element errors and determining the line quality when they exceed a preset value. A line quality monitoring device comprising: means for outputting a reference drop signal; and means for counting the sampled signal a predetermined number of times and resetting the reference drop signal at every predetermined monitoring time.