CN1236234A - Fiber optic cable monitoring system - Google Patents
Fiber optic cable monitoring system Download PDFInfo
- Publication number
- CN1236234A CN1236234A CN99105287A CN99105287A CN1236234A CN 1236234 A CN1236234 A CN 1236234A CN 99105287 A CN99105287 A CN 99105287A CN 99105287 A CN99105287 A CN 99105287A CN 1236234 A CN1236234 A CN 1236234A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- signal
- optical
- monitor
- moisture content
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Method and system for monitoring the condition of fibre optic commanication cables. By using two separate laser sources and simultanously monitoring the optical losses at two distinct and separate wavelengths, the loss signature is determined, analyzed and related to mechanical condition of the cable structure. Every splice location is assigned a unique sensor code. The optical splice sensor is driven by moisture detection cell, which forms a signal cell water activated battery. Water entering the monitored splice closure wets the tape, which activates the cell. The cell generates sufficient voltage and current to power timing, code generation and modulator circutis in the sensor unit for an extended period of time. The modulated light is momitored at the equipment and the address of alarming sensor decoded.
Description
The application is that Chinese patent application number is 93104451.0, the applying date is on April 14th, 1993, be entitled as the dividing an application of patent application case of " fiber optic cable monhoring system ".
The present invention relates to the monitoring of telecommunication cable, relate more specifically to the monitoring of optical fiber communication cable.
Phone and some other telecommunication cables will stand environment and the people is damage and the abrasion that cause.Can damage the cable of exposure such as bad weather environment such as strong wind, ice and snow, rainwater mighty torrent and thunders and lightnings.Building or destruction near harm may come from.It is a main cause that causes service disruption (broken string) that rainwater or underground water immerse in impaired part cable core or the adapter piece.Therefore, people have made the state that various effort keep cable to be in being in good repair, and anti-sealing enters among the construction of cable.
Frequently, damage does not cause the forfeiture of service immediately, but causes cable system slowly to degenerate, and this slowly degenerating usually causes cable failure and service disruption.Then must under very urgent situation, carry out its reparation later.This very high rehabilitation expense of will paying wages on the one hand also causes the loss on the income on the one hand.
Begin till now from first leader cable equipment, using some to safeguard that monitoring system is to provide the early warning of cable fault.Time that this makes people to be ranked to safeguard and avoid losing service and expensive reparation.The earliest system uses air pressure to prevent water breakthrough cable or adapter piece, and comes detection failure by the air velocity that measurement enters the cross-section of cable.
Modern telephone cable comprises fibre-optic cable, is usually filled by the water proof mixture, flows among the cable core to prevent water.Though provide good resistance for the water enchroachment (invasion) evil, the composition of filling also stops or has seriously limited flowing of air, thereby makes the air pressure monitoring system become useless.In order to overcome this restriction, and safeguard monitoring, developed some all-electronic systems, as 5,077, No. 526 described those systems of United States Patent (USP) of people such as people's such as McNaughton No. 4,480,251, United States Patent (USP) and Vokey for the telephone cable that is filled provides.
Be the fibre-optic cable that is configured under some applicable cases, comprise that fibre-optic cable all adopts dielectric insulation material as the situation in overhead electric power transfer fixing cord or the low phase electric conductor (below phase conduc-tors) of the suspension type on launching tower.Therefore, those are just no longer suitable such as the described traditional cable of metallic conductance body component and the joint monitoring method of needing of people's patents such as people such as McNaughton and Vokey.
The OTDR technology has been used to monitor optical cable and joint, and this technology is injected optical fiber with light pulse, measures the energy of reflection again, to measure increasing of energy loss.These method costs are very high, and need be in adapter piece the specified moisture of detection fiber bending apparatus, to attempt to monitor the immersion of water, in addition, the characteristic of joint bending apparatus always can not expect, and must accurately know the definite optical distance to each joint.Although preferably can adopt active checkout gear at the tap points place, the main difficulty that exists is for all dielectric cable, does not have practical means to provide power supply to operate these devices to the joint.
The present invention be directed to these above-mentioned problems and propose, and provide a kind of here according to each side of the present invention and be used to monitor the construction of cable and the mechanism that obturator damages is closed up in butt joint.
The application relates to a kind of moisture sensing signal generator, is used to detect butt joint and closes up the moisture content intrusion of obturator and send the signal that has moisture content to invade along optical fiber.
According to an aspect of the present invention, provide a kind of fiber optic cable monhoring system here, be used to monitor the physical state of at least one monomode fiber, described optical fiber has first and second ends, and described fiber optic cable monhoring system comprises:
Optical signal generating apparatus, be used to produce first and second monitor signals of light with different wave length, the wavelength that described first signal has is to select according to the macrobending of the optical fiber that transmits described first signal, so that produce significantly decay, the wavelength that described secondary signal has is to select according to the macrobending of the optical fiber that transmits described first and second signals, so that provide than the less decay of described first signal, and the wavelength of described first and second signals is to select according to the microbend of the optical fiber that transmits these two kinds of signals, so that produce identical attenuation;
Be used for sending simultaneously the device that described two kinds of monitor signals enter the first end of described optical fiber;
The optical receiver device is coupled to the second end of described optical fiber on the optics, be used for receiving simultaneously described two kinds of monitor signals;
Signal processing apparatus, it comprises:
Be used to separate the device of described two kinds of monitor signals; With
Be used to measure the device of the amplitude of described separated signal.
The extent of damage of signal shows the situation of optical cable, and for example, for the signal that wavelength is 1300nm and 1550nm, loss identical on two wavelength can be thought what microbend caused.Microbend may be because optical cable extruding or certain temperature relevant with causing the cable configuration variation cause.Only when 1550nm significantly loss increase may be relevant with macrobending, macrobending normally since the twist and warping of optical cable or optical cable volume scratch and cause.
Light signal is preferably modulated with selected frequency.When receiving, composite signal is converted into light signal, and is filtered then, so that isolate described two kinds of signals.
Light signal can be produced by two lasers, and is assigned to many optical fiber.Then, each optical fiber is monitored by receiver separately, and the output of receiver is scanned by a multiplexer, and the output of multiplexer offers the monitoring of a routine and makes alert Tip element.
According to another aspect of the present invention, provide a kind of method that is used to monitor monomode fiber here, described optical fiber has a terminal end and a reception end, and described method may further comprise the steps:
From described terminal end, along described optical fiber, transmit first light signal with first wavelength, described first wavelength is to select according to the macrobending or the microbend of described optical fiber, so that this signal is produced significantly decay;
From described terminal end, along described optical fiber, also transmit second light signal simultaneously with second wavelength, described second wavelength is to select according to the microbend of described optical fiber, so that this signal is produced significantly decay, and select according to the macrobending of this optical fiber, so that described secondary signal is produced than the obviously less decay of described first signal;
Monitor described two kinds of signals in described reception end; And
Determine the extent of damage of these two kinds of signals.
According to a further aspect of the invention, provide a kind of optical cable monitoring system here, be used to monitor the physical state of many optical fiber, every optical fiber among described many optical fiber all has first and second ends, and described optical cable monitoring system comprises:
The optical signal transmitter device, it comprises: the device that is used to produce two kinds of monitor signals of the light with different wave length; And coupler device, be used to transmit the first end that described monitor signal enters described optical fiber with being equal to;
The optical receiver device, it comprises: a plurality of optical receivers, each optical receiver all couples light to the second end of each bar optical fiber, is used to receive described monitor signal;
Signal processing apparatus, it comprises: a plurality of processors, each processor all is connected to a corresponding receiver among described a plurality of receiver, is used to separate described by a corresponding monitor signal that optical fiber transmitted among many optical fiber, and measures its amplitude; And multiplexer apparatus, be connected to described each processor, be used to scan the output of described processor; And
At least one banjo fixing butt jointing, at least one optical fiber of described optical fiber, and with it the corresponding moisture content sensing signal generator relevant with each described banjo fixing butt jointing, be used to respond intrusion at described banjo fixing butt jointing place sensing moisture content.
These aspects of the present invention will be described in detail hereinafter in conjunction with the following drawings.Below in conjunction with accompanying drawing these aspects of the present invention will be described in further detail.
Fig. 1 is the schematic diagram according to monitoring system of the present invention; Fig. 2 is the schematic diagram of fiber optic emitter; Fig. 3 is the schematic diagram of photodetector unit; Fig. 4 is the profile of a joint; Fig. 5 is the profile of moisture acquisition sensor device; Fig. 6 is the curve chart of expression optical fiber splice coupling loss with respect to the optic fibre end skew; Fig. 7 is the schematic diagram of optical receiver; Fig. 8 is the schematic diagram of an alternative embodiment of photodetector unit; Fig. 9 is the curve chart of expression optical fiber splice coupling loss with respect to the optic fibre end axial separation.
Referring to accompanying drawing, particularly Fig. 1 shows a fiber optic cable monhoring system 10 that is associated with fibre-optic cable 12.Shown optical cable is a single mode (sm) optical cable, and its length is up to 100Km.Shown optical cable comprises one along 14 parts of the joint on its length direction.Usually, a complete cable can comprise a lot of joints.This optical cable comprises a lot of root optical fiber 16.
Receiving terminal at optical fiber is an optical receiver 20 (Fig. 7), and it detects the laser that intercepts on the diode 42 and detect from each monitored optical fiber at a PIN, and described light converts the signal of telecommunication to by diode, and this signal of telecommunication is amplified by preamplifier 44.This signal of telecommunication comprises frequency content F1 and F2, and they are by band pass filter 46 and 50 separated coming, and measured circuit 48 and 52 is measured.Calculate the optical attenuation of fiber lengths on two wavelength by the amplitude of measuring.
Optical receiver also comprises a pulse detector 54, in order to monitor the pulse that produces in the photodetector unit.This photodetector unit will be described in more detail in the back.
The output of optical receiver is sent to multiplexer 56, and the latter is scanned the output from each monitored optical fiber, and provides input to central office's terminal 58; Central office's terminal 58 comprises warning circuit 58, gives the alarm when exceeding a predetermined maximum attenuation at detected optical fiber attenuation.This terminal also comprises a decoding circuit 60, in order to deciphering from the pulse of pulse detector 54.
Referring to Fig. 3,4 and 5, joint 14 comprises a modulator 62 especially, is used for producing pulse at the light by each optical fiber emission and detects for pulse detector 54.Modulator comprises a joint 64 that has V-type groove 66, and V-type groove 66 makes by the termination of the monitored optical fiber of cable joint and aimed at.In the joint, optic fibre end 70 has a very little ferrous metal element 72 that is connected in its end face.It is positioned under the utmost point of being close to modulator electromagnet 74.This ferromagnet 74 electrically is connected between the collector electrode 78 of moisture content acquisition sensor 76 and driving transistors 80.The emitter of this transistor 80 is connected in moisture content acquisition sensor 76 its base stages 84 and then is connected in code generator 86, and the latter is connected to clock 88 again.Code generator all strides across the terminal of moisture acquisition sensor 76 with clock and is connected.
With 5 to 10 microns energy needed of 125 microns glass fibre deflection is considerably less.These detector circuits are designed to adopt low-voltage microwatt CMOS integrated circuit.As a result, one meter long single-sensor battery can be to modulator and relevant several weeks of some circuit supplies.Thereby guaranteed detection to wet joint.
As previously mentioned, optical receiver intercepts and detects the laser from monitored optical fiber, and converts thereof into a signal of telecommunication.Decoded in decoding circuit by the pulse that pulse detector 54 detects, to distinguish the adapter piece that pulse occurs.Be a little purposes, will produce an exclusive pulse signal for the code generator 86 of each adapter piece.
Optical attenuation on the whole optical fiber under two kinds of monitor signal wavelength is to calculate by the amplitude of each switching electrical signals of measuring.Any over proof additional optical fiber decay all obtains analyzing.
Increase if record similar decay under two kinds of wavelength, so this decay increases can be thought to be caused by microbend, and it may be because cable extruding or cause with the construction of cable change of temperature correlation.Increase if only detect tangible decay under 1550nm, problem then may be relevant with macrobending, this normally owing to cable tangle or losing of optical fiber causes.
An alternative embodiment of photodetector is shown in Fig. 8.This embodiment is different from part embodiment illustrated in fig. 3 and is that modulator has adopted the joint 100 of capillary type, and in this joint, optic fibre end is aimed in sleeve pipe 102.Optical fiber one end 104 is fixing, and the other end is movable but apply bias voltage by spring to stiff end.An iron class sleeve pipe 108 is fixed on the movable end of optical fiber.Modulator coil 110 is around the optical fiber of adjacency sleeve pipe 108.When being excited, coil detaches optic fibre end 104 with optic fibre end 106, so just the signal on the optical fiber is modulated.
The curve that coupling loss is separated with respect to the axial optical fiber termination is provided by Fig. 9.Fibre movement is carried out with a kind of like this amplitude level, promptly greater than producing same coupling loss, needed skew.
Modulator and relevant electricity and mechanical organ may be not easy to be installed among the joint carriage or other adapter assembly that is used in the adapter piece, can utilize the appropriate location of the carriage back side or side so.
Although more than described one embodiment of the present of invention, it will be appreciated that, can also make some other embodiment within the scope of the invention.Therefore, for example, the photodetector unit can adopt some non-modulators as the electromagnetic type shown in the figure.For example, can electric pulse be changed into mechanical bias and follow-up coupling attenuation with piezoelectric crystal or some other dynamo-electric modulating device.Any other device that plays the optical switch effect all can adopt.The moisture content acquisition sensor can be made by any two kinds of metals of selecting, as long as provide half suitable cell reaction under the situation that suitable electrolyte exists.Therefore be to be understood that, can not think that the present invention is only limited to disclosed specific embodiment.The present invention is only limited by appending claims.
Claims (16)
1. fiber optic cable monhoring system is used to monitor the physical state of at least one monomode fiber, and described optical fiber has first and second ends, it is characterized in that, described fiber optic cable monhoring system comprises:
Optical signal generating apparatus, be used to produce first and second monitor signals of light with different wave length, the wavelength that described first signal is had is to select according to the macrobending of the optical fiber that transmits described first signal, so that produce significantly decay, the wavelength that described secondary signal had is to select according to the macrobending of the optical fiber that transmits described first and second signals, so that provide than the less decay of described first signal, and the wavelength of described first and second signals is to select according to the microbend of the optical fiber that transmits these two kinds of signals, so that produce identical attenuation;
Be used for sending simultaneously the device that described two kinds of monitor signals enter the first end of described optical fiber;
The optical receiver device is coupled to the second end of described optical fiber on the optics, be used for receiving simultaneously described two kinds of monitor signals;
Signal processing apparatus, it comprises:
Be used to separate the device of described two kinds of monitor signals; With
Be used to measure the device of the amplitude of described separated signal.
2. monitoring system according to claim 1 is characterized in that, described optical signal transmitter device comprises: the device that is used for different signal frequencies described monitor signal being carried out amplitude modulation.
3. fiber optic cable monhoring system according to claim 2 is characterized in that, described optical receiver device comprises: be used for described monitor signal is converted into the device of the signal of telecommunication, the described signal of telecommunication has corresponding signal frequency.
4. fiber optic cable monhoring system according to claim 3 is characterized in that, described signal processing apparatus comprises: frequency discrimination device, and in order to separate described two kinds of signals of telecommunication.
5. fiber optic cable monhoring system according to claim 1 is characterized in that, described optical signal transmitter device comprises: coupler device is used for described monitor signal is sent to with being equal to the first end of a plurality of optical fiber; Described optical receiver device comprises: a plurality of optical receivers, each optical receiver all are coupled to the second end of a relative optical fiber of many optical fiber, are used to receive described monitor signal.
6. fiber optic cable monhoring system according to claim 5, it is characterized in that, described signal processing apparatus comprises: a plurality of processors, wherein each operationally is coupled to a corresponding receiver among described a plurality of receiver, is used to handle by a corresponding monitor signal that optical fiber transmitted among described many optical fiber.
7. fiber optic cable monhoring system according to claim 6 is characterized in that, also comprises: multiplexer apparatus, be connected to a corresponding processor among described a plurality of processor, and be used to scan the output of described processor.
8. optical cable monitoring system is used to monitor the physical state of many optical fiber, and every optical fiber among described many optical fiber all has first and second ends, and described optical cable monitoring system comprises:
The optical signal transmitter device, it comprises: the device that is used to produce two kinds of monitor signals of the light with different wave length; And coupler device, be used to transmit the first end that described monitor signal enters described optical fiber with being equal to;
The optical receiver device, it comprises: a plurality of optical receivers, each optical receiver all couples light to the second end of each bar optical fiber, is used to receive described monitor signal;
Signal processing apparatus, it comprises: a plurality of processors, each processor all is connected to a corresponding receiver among described a plurality of receiver, is used to separate described by a corresponding monitor signal that optical fiber transmitted among many optical fiber, and measures its amplitude; And multiplexer apparatus, be connected to described each processor, be used to scan the output of described processor; And
At least one banjo fixing butt jointing, at least one optical fiber of described optical fiber, and with it the corresponding moisture content sensing signal generator relevant with each described banjo fixing butt jointing, be used to respond intrusion at described banjo fixing butt jointing place sensing moisture content.
9. fiber optic cable monhoring system according to claim 8 is characterized in that, described banjo fixing butt jointing comprises: docking facilities, with two optical fiber ends to be docked of alignment; Described moisture content sensing signal generator comprises: modem devices, be used to be offset at least one optical fiber end among the optical fiber end described to be docked, and make it not line up with other end; And code generating device, be used to operate described modulator, be used to modulate from described a plurality of optical fiber ends one of them to another optical fiber end the light signal of process.
10. optical cable monitoring system according to claim 9 is characterized in that, described moisture content sensing signal generator comprises: the cell apparatus of moisture content monitoring is used for producing a voltage when this cell apparatus is run into water; An electric command code signal generation device is electrically coupled to described cell apparatus, produces a fault-signal when the electric energy that receives from described cell apparatus; Described modem devices is work when described fault-signal produces.
11. optical cable monitoring system according to claim 9 is characterized in that, described banjo fixing butt jointing comprises: docking facilities, and two optical fiber ends to be docked are used to align; Described moisture content sensing signal generator comprises: modem devices is used for separating coaxially described optical fiber end to be docked; And code generating device is used to operate described modem devices, with the light signal of modulation from an optical fiber end among described a plurality of optical fiber ends to another optical fiber end process.
12. optical cable monitoring system according to claim 11 is characterized in that, described moisture content sensing signal generator comprises: the cell apparatus that moisture content detects produces a voltage when this cell apparatus is run into water; An electric command code signal generation apparatus is electrically coupled to described cell apparatus, produces a fault-signal when the electric energy that receives from described cell apparatus; And described modem devices work when described fault-signal produces.
13. optical cable monitoring system according to claim 3 is characterized in that, also comprises: a plurality of banjo fixing butt jointings are positioned at described optical fiber; A plurality of moisture content sensing signal generating meanss, with among described a plurality of banjo fixing butt jointings corresponding one be associated, response senses moisture content at corresponding banjo fixing butt jointing, modulates described monitor signal; Each moisture content sensing signal generator comprises: be used to modulate the device of described monitor signal, described monitor signal has the modulation that has nothing in common with each other with other moisture content sensing signal generator.
14. a method that is used to monitor monomode fiber, described optical fiber have a terminal end and a reception end, described method may further comprise the steps:
From described terminal end, along described optical fiber, transmit first light signal with first wavelength, described first wavelength is to select according to the macrobending or the microbend of described optical fiber, so that this signal is produced significantly decay;
From described terminal end, along described optical fiber, also transmit second light signal simultaneously with second wavelength, described second wavelength is to select according to the microbend of described optical fiber, so that this signal is produced significantly decay, and select according to the macrobending of this optical fiber, so that described secondary signal is produced than the obviously less decay of described first signal;
Monitor described two kinds of signals in described reception end; And
Determine the extent of damage of these two kinds of signals.
15. method according to claim 14 is characterized in that, also comprises: the loss of two kinds of signals of response produces an alarm prompt, to represent the microbend of this optical fiber.
16. the method according to claim 15 is characterized in that, also comprises: response is the loss in described first signal only, produces an alarm prompt, to show the macrobending of this optical fiber
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99105287A CN1236234A (en) | 1999-04-30 | 1999-04-30 | Fiber optic cable monitoring system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN99105287A CN1236234A (en) | 1999-04-30 | 1999-04-30 | Fiber optic cable monitoring system |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN93104451A Division CN1046830C (en) | 1993-04-14 | 1993-04-14 | Fiber optic cable monhoring system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1236234A true CN1236234A (en) | 1999-11-24 |
Family
ID=5271942
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN99105287A Pending CN1236234A (en) | 1999-04-30 | 1999-04-30 | Fiber optic cable monitoring system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1236234A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103632510A (en) * | 2013-12-04 | 2014-03-12 | 国家电网公司 | Pre-warning system for preventing high-voltage underground long-distance-transmission power cable from being damaged by external force |
| WO2016045358A1 (en) * | 2014-09-23 | 2016-03-31 | 华为技术有限公司 | Optical fiber cabinet resource sorting device, method and optical fiber cabinet |
| CN110617946A (en) * | 2018-06-19 | 2019-12-27 | 通号工程局集团电气工程有限公司 | Quick detection device for optical cable connection quality |
| CN111398201A (en) * | 2020-06-08 | 2020-07-10 | 翼捷安全设备（昆山）有限公司 | Optical gas detector |
-
1999
- 1999-04-30 CN CN99105287A patent/CN1236234A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103632510A (en) * | 2013-12-04 | 2014-03-12 | 国家电网公司 | Pre-warning system for preventing high-voltage underground long-distance-transmission power cable from being damaged by external force |
| WO2016045358A1 (en) * | 2014-09-23 | 2016-03-31 | 华为技术有限公司 | Optical fiber cabinet resource sorting device, method and optical fiber cabinet |
| US10050701B2 (en) | 2014-09-23 | 2018-08-14 | Huawei Technologies Co., Ltd. | Apparatus and method for reorganizing resources of optical fiber cabinet and optical fiber cabinet |
| CN110617946A (en) * | 2018-06-19 | 2019-12-27 | 通号工程局集团电气工程有限公司 | Quick detection device for optical cable connection quality |
| CN110617946B (en) * | 2018-06-19 | 2021-12-28 | 通号工程局集团电气工程有限公司 | Quick detection device for optical cable connection quality |
| CN111398201A (en) * | 2020-06-08 | 2020-07-10 | 翼捷安全设备（昆山）有限公司 | Optical gas detector |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| AU2004202903B2 (en) | Method and apparatus using polarisation optical time domain reflectometry for security applications | |
| US5349182A (en) | Fiber optic cable moisture monitoring system | |
| CA2529654C (en) | Multimode fiber optic intrusion detection system | |
| KR101963853B1 (en) | Fault section detection device by connecting point of underground distribution line | |
| EP0533771B1 (en) | Video logging cable | |
| CA2372864A1 (en) | System for monitoring cables | |
| EP0136271B1 (en) | Apparatus for detecting tapping of light energy from an optical fiber | |
| CN110715752B (en) | Optical cable joint box detection system and method | |
| CN1046830C (en) | Fiber optic cable monhoring system | |
| CN1236234A (en) | Fiber optic cable monitoring system | |
| CN107123477B (en) | Existing railway through ground wire anti-theft system based on optical fiber microbend design | |
| CN1888834B (en) | Optical fiber grating sensor wave length measuring system | |
| KR970002776A (en) | Multifunctional Vibration Sensor System Using Optical Fiber | |
| CA2065785C (en) | Fiber optic cable monitoring system | |
| Holst | Fiber-optic intensity-modulated sensors for continuous observation of concrete and rock-fill dams | |
| CA2237377C (en) | Fiber optic cable monitoring system | |
| KR101883359B1 (en) | System for diagnosing deterioration of underground power cable | |
| Nan et al. | Optical Fiber Sensing System for Online Monitoring Wind-induced Vibration on Power Transmission Tower Survey | |
| US5903221A (en) | Method and apparatus for determining the moisture level in a buried splice | |
| KR102693702B1 (en) | System and method for detecting fault location of submarine cable using energy-independent sound wave generator apparatus | |
| CN112729523B (en) | Well lid anti-theft sensor based on optical fiber technology | |
| WO2016027966A1 (en) | Failure monitoring system and failure monitoring method for optoelectronic cable assembly | |
| KR20050075801A (en) | Optical signal detector | |
| WO2010119095A1 (en) | Monitoring temperature of an overhead electrical line | |
| Ransford | Christoher P. Nemarich |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C06 | Publication | ||
| PB01 | Publication | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |