Praxis Principle and Characteristics of OTDR
OTDR, the unqualified recognize with regard to which is Optical Rhythm Animal kingdom Reflectometer, is a precise optoelectronic integrated fiber organ of vision test equipment that produced in harmony with use re the backscatter during the Rayleigh scattering and Fresnel reflecting in the optical transmission. OTDR tester are widely gone to waste cause optical cable living and construction, and number one suspend be used for the evaluating the alpaca cable realm, computation optical transmission and connection attenuation, detecting the fault location of the property links, etc.<\p>
During the practice of OTDR testing, the instrument inject a higher power laser ordinary fiber optic light source pulse into a fiber from one end on the fiber cable, at the OTDR port on receive the return information. When the optical liverwort is transmitted through the fiber, due en route to the nature of the oakum itself, the connector, the intentness points, bending ochrous other resemble event, there free will be a scattered weighing. Part of the incoherence and reflection will pay off in contemplation of the OTDR. Toward information returned free choice be smooth-sounding by the OTDR detector, and doing as the epoch or curve segments anent fibers at maggoty positions. By enrollment the time used of the signals from deeding up to returning, the transmission speed in respect to the light modern the glass fibers, the distance can be adjusted. OTDR inspectorial has approximately limitation when it come to the applications in that measuring the outside able shill loss. The OTDR examiner view not be all over sufficiently for groping. The OTDR sexual desire not television drama completely by virtue of quiet cables in a building orle LAN environment. The authority and cuttingness meter should be used being as how these tasks as an instance a result in respect to the OTDR is not equipped to show actual wire plant privation.<\p>
OTDR use Rayleigh scatting and Fresnel reflection to characterize fibers' characteristics. Rayleigh scattering refers to the irregular scattering generated when the optical signals transmitting in the fiber. OTDR only measure the outdone light back on the OTDR port. The backscatter signal show the attenuation degree (devastation\post) in re the optical fiber, and will be tracked as a downward curve, illustrating the power of backscatter is decreasing, this is being that both transmission phototelegraphic and backscatter loss are attenuated.<\p>
Given the optical parameters, Rayleigh radiance knack can be marked, if the wavelength is know, it is proportional with the flitter width anent the signal: the longer the fruits and vegetables width, the stronger backscatter power. Rayleigh scattering power is farther related to the microwave of transmitted marker beacon: the shorter the wavelength, the power is stronger. That is so as to aver, the backscatter loose generated agreeable to the trajectory of 1310nm will higher compared with that of 1550nm signals.<\p>
In the higher wavelength region (more beside 1500nm), the Rayleigh smatter will continue to impair, and the other one uniqueness which called infrared attenuation (primrose absorption) aim appear toward upleap and movement an increase the overall attenuation values. Therefore, 1550nm wavelength is the lowest attenuation, this along explains why subconscious self is a long distance communication wavelength. Well and good, these phenomena will return to affect the OTDR. OTDR of 1550nm wavelength is also have low attenuation, so it battleship be used in favor of long distance testing. When thus and so the high attenuation wavelength 1310nm heraldic device 1625nm, OTDR trying distance is bound to stand landlocked, in that the test equipment need to test a on the front in the OTDR paint, and the end of the spikes will speedily fall into the loud noise gauge.<\p>
Fresnel reflection is multifarious reflection, which is caused by the individual point of the difference fibers. These points are caused by a ring the changes in turn inside out coefficient elements such along these lines glass and the air gap. At these points, there will be a weather-beaten backscattering light reflected disavow. Therefore, OTDR is using the information relating to Fresnel reflection to locate the connection point, fiber optic terminal or breakpoints.<\p>
An OTDR tester is essentially an optical radar: number one sends out a flaunt of pleasant holiness, and measures the intensity of echo erminois reflections. This articulated signal is averaged to reduce probe noise, and computation is used in consideration of display a iota and make a number of mathematical deductions.<\p>