When Do You Use OTDRs?

We have brought in various OTDR manufacturers to teach their use to our students. Since most of our attendees are contractors, we try to give them a realistic overview of what jobs they will see and what tools they will need. It is very important to understand when you need an OTDR and when it is not appropriate.

If you are installing an outside plant network such as a long distance network or a long campus LAN with splices between cables, you will want an OTDR to check if the fibers and splices are good. The OTDR can see the splice after it is made and confirm it's performance. It can also find stress problems in the cables caused by improper handling during installation. If you are doing restoration after a cable cut, the OTDR will help find the location of cut and help confirm the quality of temporary and permanent splices to restore operation. On singlemode fibers where connector reflections are a concern, the OTDR will pinpoint bad connectors easily.

OTDRs should not be used to measure cable plant loss. That is the job of the source and power meter, which duplicates the actual fiber optic link, as we described in the first part of this article and is documented by every standard ever written for cable plant loss. The loss measured will not correlate between the two methods; the OTDR cannot show the actual cable plant loss that the system will see.

The limited distance resolution of the OTDR makes it very hard to use in a LAN or building environment, where cables are usually only a few hundred feet long. The OTDR has a great deal of difficulty resolving features in the short cables of a LAN and is more often than not simply confusing to the user.

And one OTDR manufacturer once told one of our Fiber U classes that they could justify the cost of an OTDR simply by using it to test the length of the fiber on a reel when they get it to make sure they got what they paid for. The class laughed at the instructor and pointed out the cable manufacturers mark length on the cable jacket and a $2 calculator would do as well!

Since OTDRs are very expensive and have only specific uses, the decision to buy one must be made carefully. For that reason, most instrument rental companies will rent one for a few days or weeks when you need them. However, if you are not familiar with their operation or cannot understand the results of OTDR tests, it would be much better to hire a specialist to do the testing for you.

Source: www.fiberstore.com

DVP-321 OTDR Optical Testing Equipment Supplies For FiberStore

 

Description

One key-press measurement and one key-press storage
Shortcut key design, one key-press setup
Smart portable OTDR, large colorized LCD screen
Firm, durable, shock-proof, moisture-proof
Large storage capacity, maximum store up to 800 measurement files
Built-lithium batteries, more than 10 hours working hours
Support USB and network interface, more convenient to manage files
Model: DVP321
Wavelength(nm): 1310±20/1550±20
Dynamic Range(dB): 31/29
Event Dead Zone (m):<3m
Attenuation Dead Zone (m):<25m

General Parameters:

Distance range(Km): 5m-160km
Pulse width(ns): 5ns-10μs
Measurement time: user-defined(smart link) with real-time measurement function
Distance accuracy(m): ±（0.5m ±0.001%×range + sampling resolution）
Attenuation accuracy: ±0.01dB/dB
Loss limit(dB): 0.01dB
Loss resolution(dB): 0.001dB
Sampling resolution(m): 0.1m
Sampling points: 64000
Data storage: 800 item

Other Indicators:

LCD type: 4.0 inch TFT colorized LCD
Laser adapter: FC/PC SC/PC
Interface: USB、RJ45
Battery: built-in rechargeable Li-ion battery charging time <4 hours working time >10 hours
Power: AC/DC adapter input AC90-240V ±10% output DC18V
Operating temperature: 0~40℃
Storage temperature: -10~50℃
Relative humidity: <80%
Weight: <1.5Kg
Dimensions (mm):247×130×67mm

Fiberstore is specializing in supplying fiber optic components and network equipment, and we are trying to complete this system. For the OTDR, we provide one year warranty for each domestic and foreign brand product. If you have any problems or special requirement of this DVP-321 OTDR, please feel free to contact us. We will try our best to provide you the best service.

Fiber Optic Fault Locator

Fiber visual fault locator(VFL) is a kind of device which is able to locate the breakpoint, bending or cracking of the fiber glass. It can also locate the fault of OTDR dead zone and make fiber identification from one end to the other end. Designed with a FC,SC,ST universal adapter, this fiber fault locator is used without any other type of additional adapters, it can locates fault up to 10km in fiber cable, with compact in size, light in weight, red laser output.
handheld, single wavelength, SM/MM, 650±10nm, Output Power: 1/3/5/10mW, FC adaptor, standard accessories.
Visual Fault Locator VFL-105P Features:
Operates either in CW or Pulsed
Constant output power
Lower Battery warning
Long battery life (up to 60 hours)
Crash-proof and dust-proof design for laser head
Laser case ground design prevents ESD damage
Burning testing to ensure the reliability
Portable and rugged, easy to use
2.5mm universal connector, for 1.25mm connectors
FC (Male)-LC (Female) convertor can be provided on requests
Guarantee to CE standards include EMC,EMI, ROHS
Visual Fault Locator VFL-105P Applications:
Maintenance in telecom
Maintenance CATV
Test Lab of optical fibers
Other fiber optic measurements
FiberStore supplies all kinds of fiber optic tester, if you want to know more fiber optic products, please visit our web site.

OTDR In Fiber Construction Process Testing

As we all know, optical fiber because of light weight, corrosion resistance, immunity to electromagnetic interference image, in the area of environmental adaptability than cable, fiber optic line quality is good or bad depends on the cable quality and construction process. According to the structure of the fiber optic cable, cable construction process, in strict accordance with the specifications construction, fiber optic cable by the injury a chance. Once the fiber optic cable construction requires the help of OTDR in order to understand the status of the fiber-optic lines by the human eye is not known, it is in the maintenance and operation of the fiber optic cable lines, with OTDR testing fiber link is very important and necessary.

OTDR in fiber construction process testing generally need four tests: Incoming test,Welding before testing, After welding testing and acceptance testing after construction.

(1) before laying the fiber optic cable for each fiber in the fiber optic cable must first be tested, because the fiber optic transport from the factory to the buyer unit and then transported to the site through the middle of the up and down loading, unloading, there is no guarantee optic cablefrom damage. So, tested before laying fiber optic cable in order to draw the lines of responsibility, which is make sure the fiber optic cable is good before construction. Maintenance operations perspective, the test has two purposes: First, to ensure the cable is not damaged due to the construction, the second is to determine long cable lines, in order to avoid not long enough.

(2) Cable laying continues must also re-test, which is due to the advancement of technology, fiber splicing machines weld quality has been greatly improved, making the weld point loss is no longer the main factor of the fiber line loss. Because of splice loss is small, the optical signal after passing through the point, the changes in the optical power is not obvious when the OTDR test, not easy to judge out, but is also easy to find a test curve of the optical fiber link to splice point, On the future operation and maintenance, which will generate a lot of inconvenience: First line maintenance, resulting in picking difficult because I do not know just how long the paragraph cable; line change then not easy change contact general should be selected in the jointsthe position, because of the curve in the welding point is not obvious, may not find the fusion point can not be changed then. So, before connecting again testing to prevent the occurrence of such problems, and can verify that the fiber optic cable in the arm when no cable damage. Connection before testing and OTDR test the same way, just splice in the cable before the first test cable length and the loss of data stored, to establish the length of the line segment and the loss of the database, as an important reference for future line maintenance.

(3) Cable welding again with OTDR testing, the test has two effects: First, test weld point splice loss does not exceed the stipulated requirements, once found excessive point can again re-welding, the second is the use of testand control cable core wire, weld to hundreds-core optical fiber there is no guarantee that it will not take wrong.

Many welding cable link, link the individual excessive weld point, generally speaking, there are two reasons: First, the fiber of the reasons, that successive points at both ends of the fiber numerical aperture difference is too large, may be due to differentthe manufacturers, however, with the advances in optical fiber manufacturing technology, this difference is getting smaller and smaller; another weld reasons, caused by human negligence or fault of welding machine.

Identify failed weld point fiber link with OTDR must be carefully tested and carefully judged on unqualified to be taken seriously, otherwise this point may cause deterioration of the fiber link special fast the most direct reason.

(4) After the completion of the fiber optic cable project, but also the final test of the line, the construction side of the test cable link self-test, self-examination, self-test, the test data can be used as the reference when the subsequent acceptance, acceptance-square test according to the standardacceptance testing requirements, the length of the fiber optic cable link, link loss and splice loss, the establishment of a database of test data, as an important reference for future operation and maintenance.

Final test also can take advantage of the light source, optical power meter,, and OTDR three instruments common, before they are used to test the wear and tear of the optical signal transmission within the actual link with OTDR is to find the bad linkweld point and location.

Fiber optic link loss is measured by the light source and the optical power meter, the measurement, the transmitting end and the receiving end of each take one person, before the test, the two sides of the optical fiber in the cable of the test sequence (according to the color of the optical fiber coating material) can be agreed doingAnother advantage is that timely detection the miswiring fiber.

Source: http://www.fiberstore.com/tutorial.html

What Do You Should To Know About Fiber Optic Tester

Fiber Optic is the most effective way of transferring data. At present, fiber optic is the one of the great innovations in modern telecommunications technology. Just like all other forms of technological wonders, fiber optic needs to be tested for defects which can possibly block its transmission efficiency. We need a device called a fiber optic tester to do this.

Contamination and damages are the two main reasons why fiber optics can lose its efficacy. An optical can become tainted by dust and oil deposits in its transmission path and it can also be harmed by the
natural wearing away or cracks and pits formed in the thread. With a high-quality fiber optic tester, there wouldn't be any difficulty detecting these defects. And with the convenience of different types of testers in the market, there is a device to test fiber optics and other related tools like gigabit converters and XFP transceivers.

The one kind of tool is continuity tester. It uses a light source to transmit light from one of the fiber and detect light at the other end to detect any possible defects. Although continuity tester can
identify the flaw, they are impractical when it comes to providing a detailed data about the type of flaw. The insertion loss tester is another kind of device, which is a good thing. Information about the total loss in the fiber per kilometer in addition to highlighting the bends, splices and links in the fiber or transceiver is supplied by the insertion loss tester. But the OTDR or optical time domain reflectometer is the best type of fiber optic tester.It doesn't only provide the extensive data about the damage such as length and splice losses, connector losses and fiber defects at the same time it also stores data electronically. It is considered as the most advanced tester.

It's not enough only to find out the flaws in the optics, but these defects should be eliminated by cleansing the cables themselves. You can clean them by using a solvent like isopropyl alcohol or better yet, use fiber specific solvents or air blast the fiber cables.

But then again, you don't need to assess them anymore, if you make use of the highest quality optics, since you're quite convinced that these fiber optics adopted industry standard quality specifications for efficiency and functionality and can endure contamination and damages for a long time. So, to avoid the hassle of testing and buying fiber optics tester, begin with buying the best fiber optic cables, gigabit converters and sfp transceivers from a trusted leader in transceivers.

Source: http://www.fiberstore.com

10mW New Visual Fault Locator For Sale In FiberStore

 

Fiber visual fault locator is is a kind of device which is able to locate the breakpoint, bending or cracking of the fiber glass. It can also locate the fault of OTDR dead zone and make fiber identification from one end to the other end. Designed with a FC,SC,ST universal adapter, this fiber fault locator is used without any other type of additional adapters, it can locates fault up to 10km in fiber cable, with compact in size, light in weight, red laser output.

10mW new visual fault locator fiber optic laser tester 10km is specially designed for field personnel who need an efficient and economical tool for fiber tracing, fiber routing and continuity checking in an optical network during and after installation. 

Features:

Easy to check fiber faults with visual red laser light
FC, SC, ST General interface
Sturdy and durable shell
Constant output power
Long inspection distance
Operates in either CW (Continuous wave) or pulse (Both modes are available)
Pen pattern design, convenient for use and carry
Compact in size, light in weight, red laser output, both SM and MM available

Specifications:

Wavelength: 650±10nm;
Fiber mode: SM, MM;
Output power: 10mW;
Inspection distance: 10Km;
Electrical source: 2 x AAA 1.5V Alkaline Batteries
Working time of batteries: More than 15 hours;
Operating Temperature: 10~60℃;
Storage Temperature: -40~+85℃;
Material of shell: Cu-alloy;.

FiberStore supply all kinds of high quality fiber optic products in China, such as fiber transceiver, fiber splitter, fiber optic tester and so on.

How Does OTDR Work?

OTDRs are always used on OSP cables to verify the loss of each splice. But they are also used as troubleshooting tools. Let's look at how an OTDR works and see how it can help testing and troubleshooting. When you finish this section, see Understanding OTDR for a more detailed explanation.

Unlike sources and power meters which measure the loss of the fiber optic cable plant directly, the OTDR works indirectly. The source and meter duplicate the transmitter and receiver of the fiber optic transmission link, so the measurement correlates well with actual system loss.
The OTDR, however, uses backscattered light of the fiber to imply loss. The OTDR works like RADAR, sending a high power laser light pulse down the fiber and looking for return signals from backscattered light in the fiber itself or reflected light from connector or splice interfaces.
At any point in time, the light the OTDR sees is the light scattered from the pulse passing through a region of the fiber. Only a small amount of light is scattered back toward the OTDR, but with sensitive receivers and signal averaging, it is possible to make measurements over relatively long distances. Since it is possible to calibrate the speed of the pulse as it passes down the fiber, the OTDR can measure time, calculate the pulse position in the fiber and correlate what it sees in backscattered light with an actual location in the fiber. Thus it can create a display of the amount of backscattered light at any point in the fiber.
Since the pulse is attenuated in the fiber as it passes along the fiber and suffers loss in connectors and splices, the amount of power in the test pulse decreases as it passes along the fiber in the cable plant under test. Thus the portion of the light being backscattered will be reduced accordingly, producing a picture of the actual loss occurring in the fiber. Some calculations are necessary to convert this information into a display, since the process occurs twice, once going out from the OTDR and once on the return path from the scattering at the test pulse.

There is a lot of information in an OTDR display. The slope of the fiber trace shows the attenuation coefficient of the fiber and is calibrated in dB/km by the OTDR. In order to measure fiber attenuation, you need a fairly long length of fiber with no distortions on either end from the OTDR resolution or overloading due to large reflections. If the fiber looks nonlinear at either end, especially near a reflective event like a connector, avoid that section when measuring loss.
Connectors and splices are called "events" in OTDR jargon. Both should show a loss, but connectors and mechanical splices will also show a reflective peak so you can distinguish them from fusion splices. Also, the height of that peak will indicate the amount of reflection at the event, unless it is so large that it saturates the OTDR receiver. Then peak will have a flat top and tail on the far end, indicating the receiver was overloaded. The width of the peak shows the distance resolution of the OTDR, or how close it can detect events.

OTDRs can also detect problems in the cable caused during installation. If a fiber is broken, it will show up as the end of the fiber much shorter than the cable or a high loss splice at the wrong place. If excessive stress is placed on the cable due to kinking or too tight a bend radius, it will look like a splice at the wrong location.

OTDR Limitations
The limited distance resolution of the OTDR makes it very hard to use in a LAN or building environment where cables are usually only a few hundred meters long. The OTDR has a great deal of difficulty resolving features in the short cables of a LAN and is likely to show "ghosts" from reflections at connectors, more often than not simply confusing the user.

If you want to know more fiber optic products please pay attention to my blog http://www.fiber-optic-components.com/

How To Solve The Pigtail Failure

Pigtail coiled caused by poor optical receiver no output

Analysis and Maintenance: Remove the fiber pigtail from the optical receiver pigtail head power meter measurement, the measured optical power is-1.3dB, this line distance is about 2.7km (per kilometer loss of 0.3dB)there is also a splice loss of 02dB, normal output pigtail. Turn on the power of the optical receiver, then access pigtailed optical receiver, the Signal Level Meter measured the optical receiver output is 98dB normal wear light output in the receiver cover not open the optical receiver lid pigtail no well plate, resulting in part of the pigtails pressure on the lid of the optical receiver crevices, resulting in no light power input to the optical receiver, re-plate a good pigtail, optical receiver back to normal, troubleshooting .

Pigtail head cleaning, resulting in the optical receiver output signal level is low

Analysis and Maintenance: The optical power meter to measure tail-4.5dB (cable optical power standards for 0-3dB), and then the Signal Level Meter the Metering receiver output signal level is about 48dB, is obviously not normal. Examination revealed a pigtail connecting the optical receiver of light dust, dirt, cotton ball with alcohol to wipe clean dust and dirt of the pigtail head, the then pigtail received optical receiver, and the Signal Level Meter measured the optical receiver output 98dB normal troubleshooting.

Overhaul Summary: The cause of the failure of these two cases is caused by the maintenance staff, careless in the connection of the pigtail and optical receiver in the repair process should pay attention to the end of the suspect's coiled correctly, pigtail less than 2cm in diameter bend, it will cause a greater attenuation. In addition, the connection must ensure that the pigtail head clean, so as to avoid failure.

Pigtail and poor fiber splicing, resulting in the optical receiver signal turtle output

Analysis and Maintenance: the face of this failure, first check the front-end optical transmitter and optical splitter is normal, if normal, check the optical node is normal, because this fiber optic cable distance of 2.7km. There are two splices. Pigtail head power meter measurement, found that the line failure, with OTDR measurements, measured at the 2.4km around the local failure in the front-end optical splitter. Because the first splice has passed, we can conclude that the fault lies between the fiber and pigtail. View and then weld the box fiber pigtail contacts are connected. Look contacts weld, but poor welding. Resulting in no light power output, call off the welding point, re-use of automatic welding machine for fiber and pigtail splicing. Welding a good measurement of contact loss is 0.2dB, normal. Using the power meter measured the optical transmission link loss is-1.4dB, normally, and the fiber pigtail box fasten, then pigtail connects to the optical receiver. Signal Level Meter to measure the optical receiver RF output signal level is 98dB normal optical receiver back to normal work and troubleshooting.

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What is OTDR And How To Use?

OTDR (OpticalTimeDomainReflectmeter) OTDR Optical Time Domain Reflectometer (OpticalTimeDomainReflectmeter) is short for Optical Time Domain Reflectometer test of its fiber has a non-destructive, single-ended intervention, intuitive and fast unique advantages. With OTDR optical fiber testing can be divided into three steps: parameter setting, access to data and curve analysis. Manually set the measurement parameters including wavelength selection, and pulse width settings, measuring range, the average time.

(1)Select the wavelength: due to the different wavelengths corresponding to different light enamel reactor characteristics, general test wavelength should follow the principle of corresponding to the communication system transmission wavelength, that is open 1310nm wavelength, the test wavelength of 1310nm.

(2)Set the pulse width: the longer the pulse width, the greater the dynamic range, the longer the distance measurement, but have a greater test blind, short-pulse injection test short distance, but can reduce the blind spot.

(3) Measuring range: OTDR measurement range refers to the OTDR to obtain the maximum distance of data sampling, the choice of this parameter determines the size of the sampling resolution, the best measurement range of about 1.5 times the length of the fiber under test.

(4) The average time: Due to the scattered light signal is extremely weak, the general use of statistical averaging method to improve the signal to noise ratio, the average of the longer signal to noise ratio the higher the The general idea of the fault location in optical transmission systems: the first external, after the transfer. That is the fault location, first rule out the possible factors of the external, such as broken cables, power outages, and then consider the transmission equipment.Therefore, how to accurately locate the point of failure significant cause live Chui plug ring suck, resulting in displacement of lower. Lower the temperature, we can solve the problem.

Here we must note two points: (1) the environmental temperature is not high, does not exceed 40 ℃. (2) If the valve leakage, high temperature exhaust gas will return to the cylinder. At this time we should carefully check valve grinding disc or replace the valve, to eliminate air leaks, it was possible to solve the ultra-high temperature. Changde Ling Park Hunan oil-free air compressor air compressor for each field, to dusting pile driver, live Chui plug no oil, oil air compressor, screw air compressor, shotcrete, air compressor machine equipment, sand blasting anti-corrosion, fully equipped production facilities, manufacturers of direct leasing, and construction.

This blog reproduced from http://www.fiber-optical-networking-products.com/ more information please visit fiberstore.