CN102778635B

CN102778635B - Method and device for detecting cable faults

Info

Publication number: CN102778635B
Application number: CN201210253310.5A
Authority: CN
Inventors: 魏茂林; 曹炜; 唐华; 罗旋
Original assignee: Huawei Technologies Co Ltd
Current assignee: Guangdong Gaohang Intellectual Property Operation Co ltd; Taizhou Haitong Asset Management Co ltd
Priority date: 2012-07-20
Filing date: 2012-07-20
Publication date: 2014-11-05
Anticipated expiration: 2032-07-20
Also published as: CN102778635A

Abstract

An embodiment of the invention provides a method and a device for detecting cable faults, and relates to the field of communication. By the aid of the method and the device, problems caused by short-line overshoot or long-line attenuation in a measurement process can be solved without increasing hardware circuits. The method includes measuring long-line transmitting waves, the edge jumping direction of the long-line transmitting waves and a long-line interval of long-line transmitting waves arriving at a detection end by using long-line threshold values as detection threshold values; determining reasons of the cable faults according to the long-line transmitting waves and the edge jumping direction of the long-line transmitting waves if the long-line interval is smaller than a preset time threshold value and computing to obtain positions of cable fault points according to the long-line interval; measuring short-line transmitting waves, the edge jumping direction of the short-line transmitting waves and a short-line interval of the short-line transmitting waves arriving at the detection end by using short-line threshold values as detection threshold values if the long-line interval is smaller than the preset time threshold value; then determining reasons of the cable faults according to the short-line transmitting waves and the edge jumping direction of the short-line transmitting waves; and computing to obtain the positions of the cable fault points according to the short-line interval.

Description

A kind of cable fault detection method and device

Technical field

The present invention relates to the communications field, relate in particular to a kind of cable fault detection method and device.

Background technology

In LAN (Local Area Network), between each physical layer equipment, carry out linking communications by twisted-pair feeder, conventionally the part that twisted-pair feeder can the be used as buildings hidden regions such as wall that are laid in, in network fault diagnosis and network operation, need cable to diagnose, the type that judges whether cable is correctly laid, cable breaks down position and fault is open circuit or short circuit.

In prior art, the fault detect of cable is often adopted to TDR (Time Domain Reflection, Time Domain Reflectometry) method, checkout equipment is at a transmitted wave of the test side of cable transmitting, this transmitted wave is propagated in cable, in the time running into cable fault point, this transmitted wave is reflected back toward test side, checkout equipment judges that by the waveform of the reflection wave of returning in test side detection of reflected the fault of described cable is open circuit or short circuit, in the time detecting that the waveform of reflection wave and the waveform of described transmitted wave are in the same way, the fault that judges described cable is open circuit; In the time detecting that the waveform of reflection wave and the waveform of described transmitted wave are reverse, the fault that judges described cable is short circuit; Arrive the time interval of test side by the described transmitted wave and the described reflection wave that measure simultaneously, then coordinate the velocity of propagation of waveform in cable, just can calculate the position of the trouble spot that obtains described cable.

In said method, need in checkout equipment, preset a suitable detection threshold, but in the time that the cable between trouble spot and test side is short-term, to cause transmitted wave also not send completely, reflection wave just returns, reflection wave and transmitted wave superpose mutually, produce overshoot, and the too small waveform that causes of detection threshold is difficult to judgement; In the time that the cable between trouble spot and test side is long line, reflection wave is through serious decay, and while arriving test side, its amplitude can be less than detection threshold, causes waveform to be difficult to detect.In current test way, for addressing the above problem, generally can apply hybrid circuit and deduct in advance transmitted wave, make checkout equipment reflection wave only can be detected, so just need to increase extra hardware resource.

Summary of the invention

Embodiments of the invention provide a kind of cable fault detection method and device, the problem of bringing due to short-term overshoot or long line attenuation in can solving testing process in the situation that not increasing hardware circuit.

For achieving the above object, embodiments of the invention adopt following technical scheme:

A kind of cable fault detection method, comprises

Taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and grow line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple;

Judge whether the described long line time interval is less than Preset Time threshold value;

If the described long line time interval is not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval;

If the described long line time interval is less than described Preset Time threshold value, taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave; Then according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

A kind of cable fault detection method, comprising:

Taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave;

If the described long line time interval is not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval; If the described long line time interval is less than described Preset Time threshold value, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described short-term time interval.

A kind of cable fault detection apparatus, comprising:

The first long line detecting unit, for taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and length line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple;

The first judging unit, for judging whether the described long line time interval is less than Preset Time threshold value.

The first results verification unit, for in the time that the described long line time interval is not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval;

The first short-term detecting unit, for in the time that the described long line time interval is less than described Preset Time threshold value, taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave;

Described the first results verification unit, also in the time that the described long line time interval is less than described Preset Time threshold value, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

A kind of cable fault detection apparatus, comprising:

The second short-term detecting unit, for taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave;

The second long line detecting unit, for taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and length line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple;

The second judging unit, for judging whether the described long line time interval is less than Preset Time threshold value;

The second results verification unit, for in the time that the described long line time interval is not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval; In the time that the described long line time interval is less than described Preset Time threshold value, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described short-term time interval.

Cable fault detection method and device that technique scheme provides, the method for carrying out twice detection by two detection thresholds are set can solve the problem that the overshoot of testing process middle short line or long line attenuation bring in the situation that not increasing hardware circuit.

Brief description of the drawings

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, do not paying under the prerequisite of creative work, can also obtain according to these accompanying drawings other accompanying drawing.

The schematic flow sheet of a kind of cable fault detection method that Fig. 1 provides for the embodiment of the present invention;

The schematic flow sheet of the another kind of cable fault detection method that Fig. 2 provides for the embodiment of the present invention;

A kind of cable fault detection apparatus that Fig. 3 provides for the embodiment of the present invention;

The another kind of cable fault detection apparatus that Fig. 4 provides for the embodiment of the present invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiment.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.

The embodiment of the present invention provides a kind of cable fault detection method, as shown in Figure 1, said method comprising the steps of:

101, taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and grow line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple.

If in Ethernet there is fault in somewhere cable, need testing staff to carry out cable fault detection to this place's cable, detect cable failure cause and position of failure point.The test side that cable fault detection apparatus is arranged on cable by testing staff starts to carry out cable fault detection.

In cable fault detection apparatus, be preset with two detection thresholds, a long line threshold value, a short-term threshold value.Described long line threshold value is less than described short-term threshold value, and described long line threshold value setting very little can ensure can detect when cable between test side and trouble spot is long line the hopping edge of reflection wave; Described short-term threshold value setting larger, can ensure that overshoot when cable between test side and trouble spot is short-term can not affect the correctness of detection.

Described cable fault detection apparatus is first taking the long line threshold value preset as detection threshold, application window detection method detect obtain long line transmitted wave and grow line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple.

Windows detecting method described here comprises: the hopping edge using first hopping edge detecting in detection window as transmitted wave, last hopping edge is as the hopping edge of reflection wave, thus obtain described transmitted wave and reflection wave along saltus step direction; Measure described first hopping edge and described last hopping edge and arrive the time interval of described test side, thereby obtain described transmitted wave and reflection wave and arrive time interval of described test side; Described detection window is the time period between the detection preset starts to finish to detection.

In actual testing process, described cable fault detection apparatus sends transmitted wave from the test side of cable, the time of described transmitted wave arrival test side can calculate, the twisted-pair cable length of agreement support in Ethernet is no more than 100 meters, velocity of propagation by ripple in cable can calculate transmitted wave arrival trouble spot and reflect used maximum duration again, arriving time of test side and transmitted wave according to transmitted wave arrives trouble spot and is reflected back maximum duration that test side uses again can to obtain the time period of detecting between starting to finish to detection be the size of detection window.In described detection window, can ensure to detect that the hopping edge of transmitted wave can detect again the hopping edge of reflection wave.

In actual testing process, first hopping edge detecting in described detection window must be the hopping edge of transmitted wave, the each hopping edge behind first hopping edge be all likely reflection wave along saltus step; But known to general knowledge, first hopping edge must be the hopping edge of transmitted wave, last hopping edge must be the hopping edge of reflection wave.Based on above situation, on the detection strategy of reflection wave, the embodiment of the present invention adopts the way since second along saltus step continuous detecting in detection window, often detect that a hopping edge all sets it as last hopping edge, detected value using its testing result as reflection wave, result to reflection wave refreshes, until detection window finishes, last result before detection finishes is as the result of real reflection wave.

In waveform judgement, adopt along (rising edge, negative edge) detect way, first detecting is along the edge that is transmitted wave, be first timer time t1 this moment, successfully detecting that first is after saltus step, subsequent detection to along be all reflection wave along saltus step, the timer time along saltus step with the reflection wave that detects at every turn upgrades second timer time t2, until final along saltus step be real reflection wave along saltus step, timer time is the waveform jumping moment t2 of reflection wave, the difference DELTA t of first timer time t1 and the second timer time t2 is as the foundation of weighing line length.

Cable fault detection apparatus is in the time starting to detect, first send long line transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking long line threshold value as detection threshold, hopping edge using first hopping edge detecting as long line transmitted wave, record long line transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Using second hopping edge detecting as the hopping edge of long line reflection ripple, record long line reflection ripple hopping edge along saltus step direction (rising edge or negative edge), to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of long line reflection ripple, more the hopping edge of the long line reflection ripple of new record along saltus step direction (rising edge or negative edge), and the second timer time t2.Until detection window finishes, last hopping edge detecting before finishing along saltus step direction and moment, be exactly final long line reflection ripple hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described long line time interval Δ t1=t2-t1.

102, judge whether the described long line time interval is less than Preset Time threshold value.

If the 103 described long line time intervals were not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

The size of the more described long line time interval and described Preset Time threshold value, if described long line time interval Δ t1 is not less than described Preset Time threshold value, the cable between known cable fault point and test side is longer, with the result that described long line threshold value detects as detection threshold be correct, therefore can according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

Here, describedly confirm that along saltus step direction cable fault reason specifically comprising according to described long line transmitted wave and long line reflection ripple: in the time of described long line transmitted wave and described long line reflection ripple consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described long line transmitted wave and described long line reflection ripple inconsistent along saltus step direction, confirm that described cable fault is short circuit.While being rising edge in the hopping edge of described long line transmitted wave, the hopping edge of the long line transmitted wave detecting is rising edge, confirms that described cable fault is for open circuit; The hopping edge of the long line transmitted wave detecting is negative edge, confirms that described cable fault is short circuit.

According to the described long line time interval, and the transmission speed of ripple in cable just can calculate described cable fault point position.

If the 104 described long line time intervals were less than described Preset Time threshold value, taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

If described long line time interval Δ t1 is less than described Preset Time threshold value, the cable between known cable fault point and test side is shorter, the result detecting as detection threshold by described long line threshold value is inaccurate, therefore need to be taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

Cable fault detection apparatus is sending short-term transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking short-term threshold value as detection threshold, hopping edge using first hopping edge detecting as short-term transmitted wave, record short-term transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Hopping edge using second hopping edge detecting as short-term reflection wave, record short-term reflection wave hopping edge along saltus step direction (rising edge or negative edge), to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of short-term reflection wave, more the hopping edge of new record short-term reflection wave along saltus step direction (rising edge or negative edge), and the second timer time t2.Until detection window finishes, last hopping edge detecting before finishing along saltus step direction and moment, be exactly final short-term reflection wave hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described short-term time interval Δ t2=t2-t1.

105, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

Describedly confirm that along saltus step direction cable fault reason specifically comprising according to described short-term transmitted wave and short-term reflection wave: in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.While being rising edge in the hopping edge that described short-term transmitted wave detected, the hopping edge of the short-term transmitted wave detecting is rising edge, confirms that described cable fault is for open circuit; The hopping edge of the short-term transmitted wave detecting is negative edge, confirms that described cable fault is short circuit.

According to the described short-term time interval, and the transmission speed of ripple in cable just can calculate described cable fault point position.

The embodiment of the present invention also provides a kind of cable fault diagnostic method, as shown in Figure 2, said method comprising the steps of:

201, taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

In Ethernet there is fault in somewhere cable, need to carry out cable fault detection, detects cable failure cause and position of failure point.Cable fault detection apparatus starts to carry out cable fault detection in the test side of cable.

Described cable fault detection apparatus is first taking the short-term threshold value preset as detection threshold, application window detection method detect obtain short-term transmitted wave and long line reflection ripple arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

First, cable fault detection apparatus sends short-term transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking short-term threshold value as detection threshold, hopping edge using first hopping edge detecting as short-term transmitted wave, record short-term transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Hopping edge using second hopping edge detecting as short-term reflection wave, record short-term reflection wave hopping edge along saltus step direction (rising edge or negative edge), to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of short-term reflection wave, more the hopping edge of new record short-term reflection wave along saltus step direction (rising edge or negative edge), and the second timer time t2.Until detection window finishes, last hopping edge detecting before finishing along saltus step direction and moment, be exactly final short-term reflection wave hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described short-term time interval Δ t2=t2-t1.

202, taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and grow line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple.

Then, cable fault detection apparatus sends long line transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking long line threshold value as detection threshold, hopping edge using first hopping edge detecting as long line transmitted wave, record long line transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Using second hopping edge detecting as the hopping edge of long line reflection ripple, record long line reflection ripple hopping edge along saltus step direction (rising edge or negative edge), to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of long line reflection ripple, more the hopping edge of the long line reflection ripple of new record along saltus step direction (rising edge or negative edge), and the second timer time t2.Until detection window finishes, last hopping edge detecting before finishing along saltus step direction and moment, be exactly final long line reflection ripple hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described long line time interval Δ t1=t2-t1.

203, judge whether the described long line time interval is less than Preset Time threshold value.

If the 204 described long line time intervals were not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

The size of the more described long line time interval and described Preset Time threshold value, if described long line time interval Δ t1 is not less than described Preset Time threshold value, the cable between known cable fault point and test side is longer, with the result that described long line threshold value detects as detection threshold be correct, therefore according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

If the 205 described long line time intervals were less than described Preset Time threshold value, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described short-term time interval.

If described long line time interval Δ t1 is less than described Preset Time threshold value, the cable between known cable fault point and test side is shorter, detect as detection threshold by described short-term threshold value result time correct, therefore can according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

The embodiment of the present invention also provides a kind of cable fault detection apparatus, and as shown in Figure 3, described cable fault detection apparatus comprises: the first long line detecting unit 301, the first judging unit 302, the first results verification unit 303, the first short-term detecting units 304.

The first long line detecting unit 301, for taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and length line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple.

In Ethernet there is fault in somewhere cable, need to carry out cable fault detection, detects cable failure cause and position of failure point.First selected test side, cable fault detection apparatus starts to carry out cable fault detection in the test side of cable.In cable fault detection apparatus, be preset with two detection thresholds, a long line threshold value, a short-term threshold value.Described long line threshold value is less than described short-term threshold value, and described long line threshold value setting very little can ensure can detect when cable between test side and trouble spot is long line the hopping edge of reflection wave; Described short-term threshold value setting larger, can ensure that overshoot when cable between test side and trouble spot is short-term can not affect the correctness of detection.

First, the first long line detecting unit 301 of described cable fault detection apparatus can be taking the long line threshold value preset as detection threshold, application window detection method detect obtain long line transmitted wave and length line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple.

In actual testing process, detect and start can calculate acquisition to detecting the moment finishing.Described cable fault detection apparatus sends transmitted wave from the test side of cable, the time of described transmitted wave arrival test side can calculate according to radiating circuit, the twisted-pair cable length of agreement support in Ethernet is no more than 100 meters, velocity of propagation by ripple in cable can calculate transmitted wave arrival trouble spot and reflect used maximum duration again, arriving time of test side and transmitted wave according to transmitted wave arrives trouble spot and is reflected back maximum duration that test side uses again can to obtain the time period of detecting between starting to finish to detection be the size of detection window.In described detection window, can ensure to detect that the hopping edge of transmitted wave can detect again the hopping edge of reflection wave.

In actual testing process, first hopping edge detecting in described detection window must be the hopping edge of transmitted wave, the each hopping edge behind first hopping edge be all likely reflection wave along saltus step; But known to general knowledge, first hopping edge must be the hopping edge of transmitted wave, last hopping edge must be the hopping edge of reflection wave.Based on above situation, on the detection strategy of reflection wave, the embodiment of the present invention adopts the way since second along saltus step continuous detecting in detection window, often detect that a hopping edge all sets it as last hopping edge, detected value using its testing result as reflection wave, result to reflection wave refreshes, until detection window finishes, last result before detection finishes is as the result of real reflection wave.Windows detecting method adopts along (rising edge in waveform judgement, negative edge) detect way, first detecting is along the edge that is transmitted wave, be first timer time t1 this moment, successfully detecting that first is after saltus step, subsequent detection to along be all reflection wave along saltus step, the timer time along saltus step with the reflection wave that detects at every turn upgrades second timer time t2, until final hopping edge is the hopping edge of real reflection wave, timer time is the waveform jumping moment t2 of reflection wave, the difference DELTA t of first timer time t1 and the second timer time t2 is as the foundation of weighing line length.

Cable fault detection apparatus is in the time starting to detect, the first long line detecting unit 301 first sends long line transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking long line threshold value as detection threshold, hopping edge using first hopping edge detecting as long line transmitted wave, record long line transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Using second hopping edge detecting as the hopping edge of long line reflection ripple, record long line reflection ripple hopping edge along saltus step direction, to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of long line reflection ripple, more the hopping edge of the long line reflection ripple of new record along saltus step direction, and the second timer time t2.Until detection window finishes, finish last hopping edge that front detection upgrades along saltus step direction and moment, be exactly final long line reflection ripple hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described long line time interval Δ t1=t2-t1.

The first judging unit 302, for judging whether the described long line time interval is less than Preset Time threshold value.

The first results verification unit 303, for in the time that the described long line time interval is not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

The size of the first more described long line time interval of judging unit 302 and described Preset Time threshold value, if described long line time interval Δ t1 is not less than described Preset Time threshold value, the cable between known cable fault point and test side is longer, with the result that described long line threshold value detects as detection threshold be correct, therefore described the first results verification unit 303 just according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

Confirm that along saltus step direction cable fault reason specifically comprising according to described long line transmitted wave and long line reflection ripple described in described the first results verification unit 303: in the time of described long line transmitted wave and described long line reflection ripple consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described long line transmitted wave and described long line reflection ripple inconsistent along saltus step direction, confirm that described cable fault is short circuit.While being rising edge in the hopping edge of described long line transmitted wave, the hopping edge of the long line transmitted wave detecting is rising edge, confirms that described cable fault is for open circuit; The hopping edge of the long line transmitted wave detecting is negative edge, confirms that described cable fault is short circuit.Meanwhile, described the first results verification unit 303 is according to the described long line time interval, and the transmission speed of ripple in cable just can calculate described cable fault point position.

The first short-term detecting unit 304, for in the time that the described long line time interval is less than described Preset Time threshold value, taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

If the first judging unit 302 judgement obtains described when the long line time interval, Δ t1 was less than described Preset Time threshold value, the cable between known cable fault point and test side is shorter, the result detecting as detection threshold by described long line threshold value is inaccurate, therefore need to be taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

The first judging unit 302 of cable fault detection apparatus is sending short-term transmitted wave to test side, start in detection hopping edge, test side simultaneously, the first judging unit 302 detects hopping edge taking short-term threshold value as detection threshold, hopping edge using first hopping edge detecting as short-term transmitted wave, record short-term transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Hopping edge using second hopping edge detecting as short-term reflection wave, record short-term reflection wave hopping edge along saltus step direction, to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of short-term reflection wave, more the hopping edge of new record short-term reflection wave along saltus step direction, and the second timer time t2.Until detection window finishes, last hopping edge detecting before end along saltus step direction and moment, be exactly final short-term reflection wave hopping edge along saltus step direction, and the second timer time t2, thus calculate described short-term time interval Δ t2=t2-t1.

Described the first results verification unit 303, also in the time that the described long line time interval is less than described Preset Time threshold value, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

Described the first results verification unit 303 confirms that along saltus step direction cable fault reason specifically comprises according to described short-term transmitted wave and short-term reflection wave: in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.While being rising edge in the hopping edge that described short-term transmitted wave detected, the hopping edge of the short-term transmitted wave detecting is rising edge, confirms that described cable fault is for open circuit; The hopping edge of the short-term transmitted wave detecting is negative edge, confirm that described cable fault is short circuit, described the first results verification unit 303 of while is according to the described short-term time interval, and the transmission speed of ripple in cable just can calculate described cable fault point position.

The embodiment of the present invention also provides a kind of cable fault detection apparatus, and as shown in Figure 4, described cable fault detection apparatus comprises: the long line detecting unit of the second short-term detecting unit 401, the second 402, the second judging unit 403, the second results verification unit 404.

The second short-term detecting unit 401, for taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

First, the second short-term detecting unit 401 of described cable fault detection apparatus is taking the short-term threshold value preset as detection threshold, application window detection method detect obtain short-term transmitted wave and long line reflection ripple arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave.

In actual testing process, first hopping edge detecting in described detection window must be the hopping edge of transmitted wave, the each hopping edge behind first hopping edge be all likely reflection wave along saltus step; But known to general knowledge, first hopping edge must be the hopping edge of transmitted wave, last hopping edge must be the hopping edge of reflection wave.Based on above situation, on the detection strategy of reflection wave, the embodiment of the present invention adopts the way since second along saltus step continuous detecting in detection window, often detect that a hopping edge all sets it as last hopping edge, detected value using its testing result as reflection wave, result to reflection wave refreshes, until detection window finishes, last result before detection finishes is as the result of real reflection wave.Windows detecting method adopts along (rising edge in waveform judgement, negative edge) detect way, first detecting is along the edge that is transmitted wave, be first timer time t1 this moment, successfully detecting that first is after saltus step, subsequent detection to along be all reflection wave along saltus step, the timer time along saltus step with the reflection wave that detects at every turn upgrades second timer time t2, until final along saltus step be real reflection wave along saltus step, timer time is the waveform jumping moment t2 of reflection wave, the difference DELTA t of first timer time t1 and the second timer time t2 is as the foundation of weighing line length.

First, the second short-term detecting unit 401 of cable fault detection apparatus sends short-term transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking short-term threshold value as detection threshold, hopping edge using first hopping edge detecting as short-term transmitted wave, record short-term transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Hopping edge using second hopping edge detecting as short-term reflection wave, record short-term reflection wave hopping edge along saltus step direction, to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of short-term reflection wave, more the hopping edge of new record short-term reflection wave along saltus step direction, and the second timer time t2.Until detection window finishes, last hopping edge detecting before finishing along saltus step direction and moment, be exactly final short-term reflection wave hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described short-term time interval Δ t2=t2-t1.

The second long line detecting unit 402, for taking the long line threshold value preset as detection threshold, cable test side application window detection method detect obtain long line transmitted wave and length line reflection ripple arrive long line time interval of described test side along saltus step direction and described long line transmitted wave and described long line reflection ripple.

The second long line detecting unit 402 of cable fault detection apparatus sends long line transmitted wave to test side, start in detection hopping edge, test side simultaneously, first cable fault detection apparatus detects hopping edge taking long line threshold value as detection threshold, hopping edge using first hopping edge detecting as long line transmitted wave, record long line transmitted wave hopping edge along saltus step direction (rising edge or negative edge), will be designated as the first timer time t1 this moment; Using second hopping edge detecting as the hopping edge of long line reflection ripple, record long line reflection ripple hopping edge along saltus step direction (rising edge or negative edge), to be designated as the second timer time t2 this moment, after this hopping edge often detected, all done the hopping edge of long line reflection ripple, more the hopping edge of the long line reflection ripple of new record along saltus step direction (rising edge or negative edge), and the second timer time t2.Until detection window finishes, last hopping edge detecting before finishing along saltus step direction and moment, be exactly final long line reflection ripple hopping edge along saltus step direction, and the second timer time t2.Thereby calculate described long line time interval Δ t1=t2-t1.

The second judging unit 403, for judging whether the described long line time interval is less than Preset Time threshold value.

The second results verification unit 404, for in the time that the described long line time interval is not less than described Preset Time threshold value, according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval; In the time that the described long line time interval is less than described Preset Time threshold value, according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described short-term time interval.

The size of the second more described long line time interval of judging unit 403 and described Preset Time threshold value, if the second judging unit 403 judges described long line time interval Δ t1 and is not less than described Preset Time threshold value, the cable between known cable fault point and test side is longer, with the result that described long line threshold value detects as detection threshold be correct, therefore the second results verification unit 404 just according to described long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the described long line time interval.

The second results verification unit 404 confirms that along saltus step direction cable fault reason specifically comprises according to described long line transmitted wave and long line reflection ripple: in the time of described long line transmitted wave and described long line reflection ripple consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described long line transmitted wave and described long line reflection ripple inconsistent along saltus step direction, confirm that described cable fault is short circuit.While being rising edge in the hopping edge of described long line transmitted wave, the hopping edge of the long line transmitted wave detecting is rising edge, confirms that described cable fault is for open circuit; The hopping edge of the long line transmitted wave detecting is negative edge, confirms that described cable fault is short circuit.Meanwhile, described the second results verification unit 404 is according to the described long line time interval, and the transmission speed of ripple in cable just can calculate described cable fault point position.

If the second judging unit 403 judges described long line time interval Δ t1 and is less than described Preset Time threshold value, the cable between known cable fault point and test side is shorter, detect as detection threshold by described short-term threshold value result time correct, therefore described the second results verification unit 404 just according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

Described the second results verification unit 404 confirms that along saltus step direction cable fault reason specifically comprises according to described short-term transmitted wave and short-term reflection wave: in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.While being rising edge in the hopping edge that described short-term transmitted wave detected, the hopping edge of the short-term transmitted wave detecting is rising edge, confirms that described cable fault is for open circuit; The hopping edge of the short-term transmitted wave detecting is negative edge, confirms that described cable fault is short circuit.Meanwhile, described the second results verification unit 404 is according to the described short-term time interval, and the transmission speed of ripple in cable just can calculate described cable fault point position.

The embodiment of the present invention provides a kind of cable fault detection method and device, by taking long line threshold value as detection threshold, detects the long line time interval along saltus step direction and arrival test side thereof that obtains long line transmitted wave and long line reflection ripple; And in the time that the long line time interval is not less than Preset Time threshold value, according to long line transmitted wave and long line reflection ripple confirm cable fault reason along saltus step direction, and calculate cable fault point position according to the long line time interval; In the time that the long line time interval is less than Preset Time threshold value, taking the short-term threshold value preset as detection threshold, detect the short-term time interval along saltus step direction and arrival test side thereof that obtains short-term transmitted wave and short-term reflection wave, then confirm cable fault reason according to short-term transmitted wave and short-term reflection wave along saltus step direction, calculate cable fault point position according to the short-term time interval, method that two detection thresholds carry out twice detection is set like this and can in the situation that not increasing hardware circuit, solves the problem that the overshoot of testing process middle short line or long line attenuation bring.

One of ordinary skill in the art will appreciate that: all or part of step that realizes said method embodiment can complete by the relevant hardware of programmed instruction, aforesaid program can be stored in a computer read/write memory medium, this program, in the time carrying out, is carried out the step that comprises said method embodiment; And aforesaid storage medium comprises: various media that can be program code stored such as ROM, RAM, magnetic disc or CDs.

The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited to this, any be familiar with those skilled in the art the present invention disclose technical scope in; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of described claim.

Claims

1. a cable fault detection method, is characterized in that, comprising:

If the described long line time interval is less than described Preset Time threshold value, taking the short-term threshold value preset as detection threshold, cable test side application window detection method detect obtain short-term transmitted wave and short-term reflection wave arrive short-term time interval of described test side along saltus step direction and described short-term transmitted wave and described short-term reflection wave, then according to described short-term transmitted wave and short-term reflection wave confirm cable fault reason along saltus step direction, calculate cable fault point position according to the described short-term time interval.

2. method according to claim 1, is characterized in that, described windows detecting method comprises:

Hopping edge using first hopping edge detecting in detection window as transmitted wave, last hopping edge is as the hopping edge of reflection wave, thereby obtain described transmitted wave and reflection wave along saltus step direction;

Measure described first hopping edge and described last hopping edge and arrive the time interval of described test side, thereby obtain described transmitted wave and reflection wave and arrive time interval of described test side; Described detection window is the time period between the detection preset starts to finish to detection.

3. method according to claim 1 and 2, is characterized in that,

Describedly confirm that along saltus step direction cable fault reason specifically comprising according to described long line transmitted wave and long line reflection ripple: in the time of described long line transmitted wave and described long line reflection ripple consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described long line transmitted wave and described long line reflection ripple inconsistent along saltus step direction, confirm that described cable fault is short circuit;

Describedly confirm that along saltus step direction cable fault reason specifically comprising according to described short-term transmitted wave and short-term reflection wave: in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit; In the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.

4. a cable fault detection method, is characterized in that, comprising:

5. method according to claim 4, is characterized in that, described windows detecting method comprises:

6. according to the method described in claim 4 or 5, it is characterized in that,

Describedly confirm that along saltus step direction cable fault reason specifically comprising according to described short-term transmitted wave and short-term reflection wave: in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit, in the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.

7. a cable fault detection apparatus, is characterized in that, comprising:

The first judging unit, for judging whether the described long line time interval is less than Preset Time threshold value;

8. cable fault detection apparatus according to claim 7, is characterized in that, described windows detecting method comprises:

9. according to the cable fault detection apparatus described in claim 7 or 8, it is characterized in that,

Described the first results verification unit, in the time that the described long line time interval is not less than described Preset Time threshold value specifically for, in the time of described long line transmitted wave and described long line reflection ripple consistent along saltus step direction, confirm that described cable fault is for open circuit; In the time of described long line transmitted wave and described long line reflection ripple inconsistent along saltus step direction, confirm that described cable fault is short circuit;

Described the first results verification unit, in the time that the described long line time interval is less than described Preset Time threshold value specifically for, in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit; In the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.

10. a cable fault detection apparatus, is characterized in that, comprising:

11. cable fault detection apparatus according to claim 10, is characterized in that, described windows detecting method comprises:

12. according to the cable fault detection apparatus described in claim 10 or 11, it is characterized in that,

Described the second results verification unit, in the time that the described long line time interval is not less than described Preset Time threshold value specifically for, in the time of described long line transmitted wave and described long line reflection ripple consistent along saltus step direction, confirm that described cable fault is for open circuit; In the time of described long line transmitted wave and described long line reflection ripple inconsistent along saltus step direction, confirm that described cable fault is short circuit;

Described the second results verification unit, in the time that the described long line time interval is less than described Preset Time threshold value specifically for, in the time of described short-term transmitted wave and described short-term reflection wave consistent along saltus step direction, confirm that described cable fault is for open circuit; In the time of described short-term transmitted wave and described short-term reflection wave inconsistent along saltus step direction, confirm that described cable fault is short circuit.