2018年2月28日星期三

OTDR Basis

by Fiber-MART.COM
With the development of technology, more and more fiber tools are available. They are used for testing at different stages of the network to meet various test requirements. These tests are used to reveal the total loss, optical return loss and fiber length, and the tests can be in a complete network or in a single fiber. Besides, the test may require further examination of the different elements of the measured link. Whether find fault in the network, or identify the characteristics of each component in the link, or locate potential problems for a fiber, all these will need to use optical time domain reflectometer (OTDR). OTDR is the ideal choice from commissioning to the optical network troubleshooting and maintenance.
 
OTDR is an optoelectronic instrument used to characterize an optical fiber. An OTDR is the optical equivalent of an electronic time domain reflectometer. It injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered (Rayleigh backscatter) or reflected back from points along the fiber. The scattered or reflected light that is gathered back is used to characterize the optical fiber. This is equivalent to the way that an electronic time-domain reflectometer measures reflections caused by changes in the impedance of the cable under test. The strength of the return pulses is measured and integrated as a function of time, and plotted as a function of fiber length.
 
During the process of OTDR testing, the instrument inject a higher power laser or fiber optic light source pulse into a fiber from one end of the fiber cable at the OTDR port to receive the return information. When the optical pulse is transmitted through the fiber, there will be a scattered reflection. Part of the scattering and reflection will return to the OTDR. Useful information returned will be measured by he OTDR detector, and act as the time or curve segments of fibers at different positions. By recording the time used of the signals from transmission to returning, the transmission speed of the light in the glass fibers, the distance can be calculated.
 
The major advantage of the OTDR is that tests can be done from one end of the link and you do not have to access to the other end. This means that you don’t need two people to do the test and then save the problems of coordinating between people. Besides, it is much quicker for the testing. So even simple tests which could be performed with a basic optical source at one end of the link and a power meter at the other are often performed with an OTDR.
 
Many modern OTDRs come with additional functions such as optical power meter or laser source so that a good OTDR often has all of the function needed by a technician in the field. Moreover, many OTDRs offer computer output so that you can collect OTDR data in the form of digital readings and analyze it later on a computer. FS.COM has many kinds of OTDRs at reasonable price. If you are looking for an OTDR, FS.COM is an excellent option.

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