IEC 61746 PDF


IEC provides procedures for calibrating multimode optical time domain reflectometers (OTDR). It covers OTDR measurement. Buy IEC CALIBRATION OF OPTICAL TIME-DOMAIN REFLECTOMETERS (OTDR) – PART 2: OTDR FOR MULTIMODE FIBRES from SAI Global. Buy IEC CALIBRATION OF OPTICAL TIME-DOMAIN REFLECTOMETERS (OTDR) – PART 1: OTDR FOR SINGLE MODE FIBRES from SAI Global.

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The answer to this question has several aspects. We recommend that insertion loss ie be done even when OTDR testing is required by installation contracts. Your Alert Profile lists the documents that will be monitored. The launch cable has also been called a “pulse suppressor” because it allows time for the OTDR to settle down from this initial overload.

Calibration of fibre optic measurement instruments

Some multimode OTDRs are now usable for short length multimode premises cables but only if they are properly set up before use and launch and receive cables have connections with low reflectance. A light is placed on one end of the cable and a power meter measures loss at the other end, just like a link transmitter and receiver use the fiber for communications.

The differences in the measurement techniques used by OTDRs and a light source and power meter means that OTDR testing, especially on longer premises cable plants with higher loss, may not be comparable to measured insertion loss or the actual loss the communications system will experience.

A ghost will not have any loss, it will be at equal distance from a highly reflective event look for repetitiontends to be in the middle of noise after the end of the cable. It only covers OTDR measurement errors and uncertainties.

IEC Ed. b – Calibration of optical time-domain reflectometers (OTDR)

As the voice of the U. Add to Alert PDF. Premises cabling, however, has short cable runs and almost never includes splices, so the requirement of OTDR testing appears to be as an alternative to insertion loss testing with a light source and power meter, which in reality, is inappropriate.


Proceed to Checkout Continue Shopping. Are there some reusable connectors in the commerce? Most OTDRs also allow setting a threshold for detection of events and that must be set correctly to recognize events.

If your network is short, the OTDR will not give you valid data. The long recovery time from this overload pulse means the OTDR cannot make any useful measurements near the instrument itself. It is designed to cover every economic sector and virtually every activity of the humankind where technical standards may be used.

Directional Results Can Be Confusing: Splice threshold Reflectance threshold Slope threshold slope is attenuation coefficient End threshold depends on whether you 1 use receive reference cable which would be a normal connection loss or 2 the length of the cable and the noise floor of the measurement.

I use bi directional analysis. Although we endeavour to maintain an up-to-date catalogue, on occasion we may not have the latest version of a document, including where it has not yet been provided through an international feed. The large event you see right in front of the instrument on the OTDR trace is caused by crosstalk within the instrument and reflectance from the connector on the face of the OTDR.

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Results are archived with other documentation to be available if restoration is necessary in the future. You are seeing the directional differences. From this trace, the OTDR calculates fiber length, attenuation and joint loss. Needless to say, it’s extremely important to understand how to use these instruments correctly.


An insertion loss test made with a light source and power meter is a simple test that is similar in principle to how a fiber optic link works.

Later OTDR testing may be used for troubleshooting problems like finding locations of cable breaks caused by dig-ups. New international testing standards, however, accept both OTDR testing and insertion loss testing, even for short premises multimode cable plants.

For testing bare fiber, use a splice, not a connector.

For a splice with 0. The actual resolution of the OTDR is usually thought of as its ability to distinguish between two points on the cable, like intermediate patchcords or closely spaced splices. Subscription pricing is determined by: Please first log in with a verified email before subscribing to alerts. Most OTDRs have a display 617446 digitized to aboutparts, ifc on a 20km range, the display resolution is 1m, or on a 2km range it would be 0.

It constitutes a technical revision. International Classification for Standards ICS is an international classification system for technical standards. I have a limit 0.

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Some manufacturers of cable can provide that information for your testing. It is important to us that you purchase the right document. It is not considered a replacement for insertion loss testing by knowledgeable fiber optic personnel. If you need help with the purchase or have any queries please email enquiries standards. Just measure the fiber on the spool of cable with the OTDR, then look at the cable jacket for length markings to get the actual length of the cable from the printed markings at each end of the cable.