What is “OTDR”
Optical Time Domain Reflectometer (OTDR). An OTDR is an optoelectronic instrument used to characterize an optical fiber. An OTDR is the optical equivalent of an electronic time domain reflectometer. The OTDR is useful for testing the integrity of fiber optic cables. It can verify splice loss, measure length and find faults. The OTDR is also commonly used to create a “picture” of fiber optic cable when it is newly installed. This is equivalent to the way that an electronic time-domain meter 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. 
OTDR is most effective when testing long cables (more than approximately 250 meters or 800 feet) or cable plants with splices.
The data that the OTDR produces are typically used to create a picture called a “trace” or “signature” that has valuable information for the trained user and can be stored for later reference or to check against a blueprint when network trouble arises. OTDRs simply show you where the cables are terminated and confirm the quality of the fibers, connections and splices. Of course, OTDR traces are also used for troubleshooting, since they
How Does an OTDR Work?
The OTDR works indirectly，use a unique optical phenomena of fiber to indirectly measure loss. The biggest factor in optical fiber loss is scattering. In fiber, light is scattered in all directions, including some scattered back toward the source The OTDR uses this “backs cattered light” to make measurements along with reflected light from connectors or cleaved fiber ends.
The OTDR will calculate the distance difference between the two markers and give the distance. It will also read the difference between the power levels of the two points where the markers cross the trace and calculate the loss, or difference in the two power levels in dB. Finally, it will calculate the attenuation coefficient of the fiber by dividing loss by distance and present the result in dB/km, the normal units for attenuation. In order to get a good measurement, it is necessary to find a relatively long section of fiber to give a good baseline for the measurement. Short distances will mean small amounts of loss, and the uncertainty of the measurement will be higher than if the distance is longer.
It is also advisable to stay away from events like splices or connectors, as the OTDR may have some settling time after these events, especially if they are reflective, causing the trace to have nonlinearities caused by the instrument itself.
This OTDR manufactured with patience and carefulness, following the national standards to combine the rich experience and modern technology, subject to stringent mechanical, electronic and optical testing and quality assurance; in the other way, the new design makes OT700 series more smart and compact and multi-purpose. Whether you want to detect link layer in the construction and installation of optical network or process efficient maintenance and trouble shooting, OT700 Series can be your best assistant.
Features:
• Integrated design, smart and rugged
• IP65 protection level, outdoor enhanced
• 7-inch anti-reflection LCD screen
• PON online test module (1625nm) is optional
• MMF test module (850/1300nm) is optional
• Support multi-language display and input
Application:
• FTTX test with PON networks
• CATV network testing
• Access network testing
• LAN network testing
• Metro network testing
• Lab and Factory testing
• Live fiber troubleshooting
