JPS5841696B2 - Titanium sakuhoshiki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for locating a fault in a transmission line configured by cascading a plurality of repeaters and lines.

Examples of conventionally known fault location searching methods are shown in FIGS. 1 and 2.

Figure 1 shows what is called a resistance monitoring system, where 1 is a transmission line,
2 and 2' are monitoring intervening pairs, 3 is a monitored repeater, 4 is a resistor assigned to each repeater, 5 is a pilot detection circuit, and 6 is a switch.

The output of the pilot detection circuit 5 causes a switch 6 to close when the pilot signal level is abnormal.

Here, the pilot signal refers to a signal that selects one frequency within the transmission frequency band and is used for monitoring and controlling the transmission path.

If the pilot signal level suddenly becomes abnormal due to a failure in one repeater 3, the switch 6 at the relay point beyond that position is closed.

If we MIIQ the resistance value between the terminal station and the intervening pair 2, 2', we get
The location of the fault can be determined by its resistance value.

Figure 2 shows the same method (conventional method using S■ times signal), 1 in the figure.
1 is an outbound transmission line, 1' is a return transmission line, 3 and 3' are monitored repeaters, and 7 is an SVF waveform having its respective pass frequency band.

Here, the SV signal refers to a signal for searching for a fault location by assigning a different frequency to each repeater from a monitoring frequency band provided in a part of the transmittable frequency band of the transmission path.

Further, the SVP wave device is an E wave device with an assigned frequency used for this purpose.

f1 to f3 indicate S■ times the signal frequency.

Now, if the terminal station transmits frequencies f1 to f3 at some levels to a person or D to the transmission line 1 or 1', and measures the arrival level at B or C, it is possible to search for an abnormal location.

All of these are well-known conventional transmission path fault location methods, but in the case of the method shown in Figure 1, the pilot signal frequency is usually selected at the high frequency end of the transmission frequency band, so it is not possible to monitor abnormalities in the pilot signal level. Although it is useful for failures at high frequencies within the transmission frequency band, it has the disadvantage that position searching becomes impossible for failures at low frequencies.

Another drawback is that it requires an extra pair of lines in addition to the signal lines for monitoring purposes.

In the case of Fig. 2, the SV signal frequency is normally selected as one frequency on the low frequency side of the transmission frequency band so as not to affect the transmission signal, so it is similar to the case of Fig. 1 that the high frequency side cannot be monitored. There was a problem.

This is particularly disadvantageous in the case of broadband transmission lines.

For example, in the case of baseband transmission of a video signal with a large bandwidth in the example shown in Figure 2, even though the image quality has deteriorated due to an abnormality in the high frequency gain of each repeater or poor high frequency characteristics of the line, the If a fault occurs in which no abnormality is recognized in the SV multiplied frequency signal, it is impossible to search for the fault location from the monitoring station using this method.

In other words, when these conventional methods are used alone, fault monitoring is performed using a single frequency for each repeater, so S
■If a fault occurs in a band other than the signal frequency or pilot frequency, there is a drawback that it is impossible to locate the fault.

The object of the fault location search method according to the present invention is to provide a fault location search method that improves on the drawbacks of the conventional methods.

The method of the present invention detects an abnormality in the pilot signal level,
The feature is that the circuit to the svp wave device is opened and closed from this, and the incense stick position is searched.

That is, the present invention provides a fault location search method for a wired transmission line in which a pilot signal and an SV double signal are transmitted in a transmittable frequency band of a transmission line configured by alternately cascading a plurality of repeaters and lines. Frequency arrangement is such that the pilot signal is transmitted to one of the low frequency region and the high frequency region of the available frequency band, and the S signal to which a frequency is assigned to each repeater is transmitted to the other region. , a return line for the Sv signal, an SVP waver connected between the transmission line and the return line for extracting the S■ signal, and a SVP waveform connected to the transmission line for detecting abnormalities in the pilot signal. comprising a pilot detector and a means for opening and closing the signal path of the svp wave device in response to the detection output of this detector, and monitoring the SV multiplied signal sent to the transmission path on the return line. Features.

Further, the present invention is characterized in that it includes a means for artificially changing the pilot signal level at a terminal station or a repeater to forcibly open and close the SVp waveter circuit.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 shows an embodiment of the invention.

In the figure, 1 and 1' are transmission lines, 3 and 3' are repeaters, 5 and 5' are pilot detection circuits, 6 is a switch, and 7 is an SVP wave device.

A large number of repeaters 3, 3' are connected in cascade to the transmission lines 1, 1', and are configured to perform broadband transmission.

At each relay point, the output of the repeater 3 is coupled to the input of the repeater 3' via a switch 6 and an S'M wave unit 7, and the switch 6 is connected to the pilot terminal coupled to the output of the repeaters 3 and 3'. Detector 5
, 5'.

Here, the transmission lines 1 and 1' mutually serve as return lines for the S■ signal.

In the configuration shown in Fig. 3, the switch 6 is set to close when the pilot signal level is normal and open when it is abnormal, and
It is assumed that the v signal frequency is selected on the low frequency side within the transmission band, and the pilot frequency is selected on the high frequency side.

If one of the repeaters 3 deteriorates in the transmission characteristics of its high frequency part and becomes a fault, and if it is normal as far as the low frequency side is concerned, then the pilot signal level after the fault point becomes abnormal and the switch 6 It becomes open.

DKSV signals f1 to f3 are sent from the terminal station, and f1 is sent at C.
By observing the level of ~f3, it becomes possible to search for the location of the fault.

Conversely, when the transmission characteristics of the low frequency portion deteriorate and the pilot signal signal is normal, it becomes possible to search for the fault location using the same method as in the conventional case described in FIG.

As described above, according to the method of the present invention, even if there is a partial fault on the low frequency side or the high frequency side of the transmission frequency band, the fault location can be searched without requiring an extra monitoring intervening pair. This method has the advantage that fault searching can be performed effectively for faults in all frequency bands formed by the transmission path.

FIG. 4 shows another example of implementing the present invention.

This is configured to keep the S'M wave device circuit open when the pilot signal is normal and close it when the pilot signal is abnormal.

Each switch 6,6 opens when the pilot signal level is normal, and closes when the pilot signal level is abnormal.
Controlled by

The symbols of each part and their operations are the same as those in FIG. 3.

In such a system, when the pilot signal level is abnormal, the SVP waveform circuit is automatically entered, so that the position search can be performed in the same manner as the conventional system described in FIG.

If only the SV signal frequency band becomes abnormal during operation, all signals can be forcibly removed by artificially setting the pilot signal to an abnormal level by weakening the pilot signal transmission at the terminal station or intermediate repeater. If the switches 6, 6 are closed, the second
This is exactly the same as the conventional method shown in the figure.

Here, a circuit in which the circuit is open when the pilot signal is normal is compared with a circuit in which the SVP wave device is connected to the transmission path when the transmission path is normal, and the SVf' wave device circuit has the following characteristics. Strict characteristics such as input and output impedance in the pass frequency band and attenuation in the stop frequency band are not required so as not to affect the transmitted signal.

Therefore, there is an advantage that the characteristics of the SvP waveform circuit can be simple and not so strict.

FIG. 5 shows another example of implementing the present invention, which is applied to the case where a plurality of systems are monitored simultaneously.

In the figure, 1 is each transmission line, and 8 is a common monitoring transmission line.
3 is the monitored repeater, 5 is the pilot detector, 6 is the switch, T is the sv signal frequency f1. It is an SVF waveformer with a passband for f2.

The configuration shown in FIG. 5 has the advantage that one SVP transducer can be shared for each relay point for monitoring a plurality of systems, making the system configuration economical.

As described above, the method of the present invention does not require any intervening pair of monitoring wires other than the signal line, and has the excellent effect of effectively performing fault location search over the entire transmission frequency band with a simple configuration. be.

In addition, the pilot signal mentioned in the above explanation is converted to a high frequency, S
It goes without saying that placing the V signal at a low frequency does not limit the scope of the present invention, and the frequency placement can be arbitrarily selected depending on the application of the system.

Further, the method of the present invention can be used simultaneously with other methods, such as an automatic gain control method based on the pilot signal level, by sharing the pilot signal.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are system configuration diagrams of a conventional example. FIG. 3 is a configuration diagram of an embodiment of the present invention. FIG. 4 is a configuration diagram showing another embodiment of the present invention. FIG. 5 is a configuration diagram showing another embodiment of the present invention. 1.1'...Transmission line, 2,2'...Intervening line, 3,3'...Relayer, 4...Resistor, 5 ...Pilot detector, 6...
・Switch, 7...SVP wave device, 8...
Monitoring transmission line.

Claims (1)

[Claims] 1. In a fault location search method for a wired transmission line that transmits a pilot signal and an Sv multiplied signal in the transmission frequency band of a transmission line configured by alternately cascading a plurality of repeaters and lines, The frequency is set such that the pilot signal is transmitted in one of the low frequency region and the high frequency region of the transmittable frequency band, and the S ■ times signal, which is assigned a frequency for each repeater, is transmitted in the other region. an S waveformer for extracting the Sv multiplied signal, which is arranged and connected between the return line for the SV signal and the transmission line and the return line;
a pilot detector connected to the transmission path to detect an abnormality in the pilot signal; and means for opening and closing a signal path of the SVF waver in response to a detection output of the detector; A system for locating a fault in a wired transmission line, characterized in that said S■ times signal is monitored on said return line. 2. A method for locating a fault in a wired transmission line according to claim 1, characterized in that the terminal station or repeater is provided with means for artificially changing the level of the pilot signal. .