FOA Guide to Fiber Optics 

Topic: PC Simulator For Optical Time Domain Reflectometer (OTDR)

Table of Contents: The FOA Reference Guide To Fiber Optics

Optical Time Domain Reflectometer Simulator
The OTDR Simulator is a aid to learning how OTDRs work without incurring the expense of owning a real OTDR and tons of cable. The Simulator runs on a PC but works just like a real OTDR. It is the actual operating software from a PC-based OTDR that comes with numerous traces that illustrate how the OTDR works and traces of real cable plants to analyze. The traces are raw data that is analyzed in the PC so the simulator works just like a real OTDR.

OTDR manufacturers provide basic information on using their instruments, but rarely provide an adequate variety of traces to learn from and often do not dwell on measurement uncertainty or common problems like gainers and ghosts. This is where you need the OTDR Simulator. It will help you learn how to set up the OTDR properly and analyze traces correctly.
One of the biggest problems in learning about OTDRs is understanding all the options in setting test parameters. Range, wavelength, pulse width, averages, etc. all need to be understood so the operator knows what effect they have on the trace and how to choose the proper setup for a given test situation. Learning how to interpret traces also requires having access to large numbers of cables, including some very long ones. That's not easy in a lab and impossible at home. 

With the OTDR simulator, you can learn how to use an OTDR on a PC. The simulator includes software that emulates an OTDR and two sets of traces to analyze. 

Included are two types of traces:
1) Parameter setup traces: 26 traces taken of the same cable plant, with each of the OTDR parameters changed to allow you to see the effects of changing these parameters, as shown in the pulse width comparison below. Traces highlight changes in parameters such as: wavelength, range, pulse width, fiber index of refraction, number of averages, and more.
2) Real fibers: Over 40 traces of real cable plants and 5 traces of FTTH PON couplers for you to analyze. Few classrooms can offer this many different traces to analyze - and not many have a 180 km cable run with an obvious gainer section or traces of PON couplers available!
Works Just Like An OTDR, Only Better
The OTDR simulator is the same software used with the PC-based OTDR sold by Advanced Fiber Solutions, but runs without the OTDR hardware. You can, however, buy the OTDR separately and use it with the same software. This instrument uses hardware to acquire the data but analyzes it in the PC, so our simulator can do everything the OTDR can do to analyze traces, including fiber loss by 2 point or LSA, connector/splice loss by 2 points or LSA and back reflection. You can zoom in on features, set markers, and compare traces.
You can load up to 6 traces and compare them on the same display. Below we show two traces compared, the same cable plant shot at 1300 and 850 nm test wavelengths. You can see the effect wavelength on attenuation.

Comparing Traces

comparing traces

Modifying OTDR Setup Parameters For Best Test Results
Two traces showing the effects of averaging the signal.


PC Requirements:

PC running Windows XP or Windows 7

Download the PC Simulator  (Zip file, 9.5 MB)

See the FOA Virtual Hands-On OTDR Tutorial


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