Discussion Based On The OTDR Technology Of Fiber Optic Test Method

Optical fiber communication based totally on light waves for the provider to the optical fiber as the transmission medium of conversation. Optical fiber communication transmission distance and capacity of data and verbal exchange pleasant characteristics and become the primary method of facts transmission, is the cornerstone of the "information superhighway". The fiber optic testing era is one of the most broadly used in fiber optic programs, the most primary technical expertise. OTDR is the principle device in the discipline of fiber-optic test, it is broadly used in optical fiber cable line upkeep, construction, and fiber duration, the transmission attenuation of the fiber connector attenuation and fault place measurements. The OTDR has a short test time, take a look at pace, excessive precision test.
OTDR (Optical Time Domain Reflectometer, Optical Time Domain Reflectometer) is the backscatter generated by means of the Rayleigh scattering and Fresnel mirrored image inside the use of mild pulses in optical fibers made ​​of high-tech, high-precision photoelectric integrationinstrument. Semiconductor light source (LED or LD) output mild pulse within the modulation of the power circuit, the directional optical coupler and sports connector into the measured optical fiber cable line into the incident pulse. Incident light pulse transmission line along the Rayleigh scattering of mild and Fresnel meditated light, most of the Rayleigh scattered light can be refracted into the cladding attenuation, opposite to the course of propagation of mild pulses again to Rayleigh scattering light along the optical fiber transmission line into the optical port, the directional coupler splitter fired on the photodetector into an electrical sign, low noise amplification and the wide variety average remedy can be processed alerts from the mild supply the lower back of the emission cause sign is extracted via synchronous scanning come to be a reflected mild pulse on the oscilloscope. Useful data again by way of the OTDR detector to measure them as a time or curve fragments in extraordinary places on the measured fiber. According to transmit indicators to the time of the go back signal, after which decide the velocity of mild in the quartz cloth, you may calculate the gap.

Test wavelength choice

OTDR for fiber optic communications offerings, before making optical fiber take a look at first pick a test wavelength unmarried-mode fiber to pick out best 1 310 nm or 550 nm. 1 at 550 nm wavelength on the fiber bending loss is much more touchy than the 1 310 nm wavelength, regardless of fiber optic cable line construction or fiber optic cable line protection or test, teaching, the usage of an OTDR to the whole of a cable or a fiber optic transmission hyperlink The fiber optic sign backscatter curve trying out, choice of greater than 1 550 nm wavelength. 310nm and 550 nm, the wavelength of the take a look at shape of the curve is the same, the measured optical fiber splice loss values ​​are essentially the equal. 1 550 nm wavelength trying out found no problems, then the 1 310 nm wavelength dimension is truly no hassle. Select the 1 550 nm wavelength checking out fiber complete smooth to discover whether or not there's immoderate bending of the situation. If it's far discovered someplace at the curve have a more loss steps, after which the 1 310 nm wavelength retest, 1 310 nm wavelength loss steps disappear, indicating that there does exist a bend excessively, you need to discover and put off. 1 310 nm wavelength loss steps are the equal, wherein fiber might also produce other issues, additionally want to appearance to exclude. In the single-mode fiber line take a look at, you should try to use the 1 550 nm, in order that test effects will be better.

The refractive index of fiber alternatives

Now use single-mode fiber refractive index within the range of 1.460 zero 1.480 0. To accurately decided on in line with the actual price supplied by means of the producer of fiber optic cable or fiber. For G. 652 single-mode fiber, the real check with a wavelength of 310 nm, the refractive index is typically choose 0 1.468; if 1 550 nm wavelength, the refractive index is typically pick out to 1.468 five. The refractive index pick not allowed to affect the test period. In refractive index mistakes of 0.001 (1), 50 000 m relay segment will generate the error of about 35 m. Cable renovation and troubleshooting of small errors would deliver substantial error, the test ought to be taken significantly sufficient.

Three commonplace techniques of implementation of the OTDR checking out

OTDR fiber optic cable and fiber optic take a look at season checking out events, inclusive of the preservation tests and periodic trying out of the development take a look at for factory testing of fiber optic cable and optical fiber, optical cable and fiber optic cable, fiber optic cable and optical fiber.

The OTDR forward one-way take a look at technique

OTDR check the path of the optical fiber splice connector point, check devices and testers are always beforehand of the switch of construction cars. Use this technique to monitor, take a look at factors and splices is continually simplest one cable period, the accuracy of the test connector attenuation, and to facilitate communications and liaison. A cable duration of approximately 2 to a few km, using walkie-talkie in the wellknown topography can make sure that communication hyperlinks. If the fiber optic cable corrugated metal protecting layer can also use the magnet telephone touch.

The drawback of this check approach is glaringly an OTDR to move to every take a look at point time and labor, and now not conducive to the protection of the instrument; take a look at factor to the terrain, in particular the line faraway from the street, greater cumbersome in complicated terrain. Selection of transportable OTDR monitoring at close variety to check the instrument dynamic range of less demanding, and small 0TDR quantity small, mild weight and easy to move, this may substantially reduce the workload of testers, to enhance take a look at velocity and performance.

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