How to Test Fiber Optic Cables by OTDR

by Fiber-MART.COM

OTDR, full name of which is optical time-domain reflectometer is one of the most popular method of testing the light loss in the cable plant. In most circumstance, it also indicate an fiber optic testing instrument to characterized the optical fibers. OTDRs are always used on OSP cables to verify splicing loss or locating damages to the fiber optic cables. Due to the decline in the OTDR price over recent years, it is more and more applied by technicians for the system installation process.

 

OTDR testing

 

OTDR uses backscattered light of the fiber to imply loss, which is an indirect measurement of the fiber. OTDR works by sending a high power laser light source pulse down the fiber and looking for return signals from backscattered light in the fiber itself or reflected light from connectors or splice interface. OTDR testing requires a launch cable for the instrument to settle down after reflections from the high powered test pulse overloads the instrument. OTDRs can either use one launch cable or a launch cable with a receive cable, the tester result of each is also different.

 

Test With Launch Cable Only

A long lauch cable allows the OTDR to settle down after the initial pulse and provides a reference cable for testing the first connector on the cable. When testing with an OTDR using only the launch cable, the trace will show the launch cable, the connection to the cable under test with a peak from the reflectance from the connection, the under testing cable and likely a reflection from the far end if it is terminated or cleaved. Most terminations will show reflectance that helps identify the ends of the cable.

 

By this method, it can not test the connector on the far end of the under testing cable since it is not connected to another connector, and connection to a reference connector is necessary to make a connection loss measurement.

 

Test With Launch And Receive Cable

By placing a receive cable at the far end of the under testing cable, the OTDR can measure the loss of all factors along the cable plant no matter the connector, the fiber of cables, and other connections or splices in the cable under test. Most OTDRs have a least squares test method that can substract out the cable included in the measurement of every single connector, but keep in mind, this may not workable when the tested cable is with two end.

 

During the process you should always keep in mind to start with the OTDR set for the shortest pulse width for best resolution and a range at least twice the length of the cable you are testing. Make an initial trace and see how you need to change the parameters to get better results.

 

OTDRs can used to detect almost any problems in the cable plant caused during the installation. If the fiber of the cable is broken, or if any excessive stress is placed on the cable, it will show up the end of the fire much shorter than the cable or a high loss splice at the problem locations.

 

Except OTDR testing, the source and optical power meter method is another measurement which will test the loss of the fiber optic cable plant directly, The source and meter duplicate the transmitter and receiver of the fiber optic transmission link, so the measurement correlates well with actual system loss.

Why choose fiber optic cleaning products?

All the clean freaks out there, we know what goes through your head when something does not seem clean even when you wipe it spotless. Little fragments of dust seem to be present throughout. In fact dust, dirt, oil and other particles can block signals of your fiber optic network by accumulating on the optic connectors. That is why fiber optic cleaning is the future; it is efficient in its own way and does a lot of work for its money to reduce downtime of any network.

There are different types of cleaner available in the market but let us discuss one here that is commonly used and it is fiber optic cleaning fluid.

There is no alcohol present. While some people argue that alcohol helps germs and dust particles to come off completely. The alcohol doesn’t mix well with the fiber optics and instead causes it to block the signals on its connectors. While alcohol removes germs, it can also attract new forms of dust on products.

It is environmentally safer. Due to its double filtration and alcohol free formulas, it poses no threat to the environment. These fiber cables are non toxic and non flammable so they carry no risks of potential danger anyways.

You can take it on travel anywhere and everywhere, its non hazardous nature is approved by travel authorities and it is very convenient as it is properly sealed and it is not pressurized. It is extremely economical as well. Any average person can buy this and make it worth their money with unlimited shelf life.

In this day and age, fiber optics have become a fundamental part of our lives and maintaining it that way is very important task that we need to fulfill. Repeated connection and disconnection leaves debris in the bulkheads of the different compartments, which if not attended to, can cause a major problem.

There are different types of cleaning involved in fiber optic cleaning.

• There is dry cleaning, meaning without the use of any sort of solvent

• There is wet cleaning that involves a solvent

• Non-abrasive cleaning, which involves the material not touching the fiber optic connectors and are merely air dusted.

• Then there is abrasive which is basically the opposite of non abrasive and involves wiping on the surfaces of the fiber optic.

Overall, this is the best product you can get for your money as it includes the necessary qualities to properly clean and get the job done.

The Classification Of Fiber Optic Transceivers

A wide range of fiber transceivers, corresponding changes according to different classification types.

Can be classified according to the nature of the fiber optic multimode fiber-optic transceivers and single-mode fiber transceiver. Different due to the use of fiber-optic transceivers can transfer distance is not the same multimode transceiver transmission distance of 2 km to 5 km, the area covered by the single-mode transceiver from 20 km to 120 km.

Required optical fiber can be divided into single-fiber optical transceivers: the transmission and reception of data transmission on a single fiber; dual-fiber optical fiber transceivers: the transmission and reception of data on a pair of optical fiber transmission.

Work level/rate points, can be divided into single-10M, 100M fiber optic transceivers, a 10/100M adaptive fiber optic transceivers and 1000M fiber optic transceiver. Points, according to the structure can be divided into the desktop(Independent) fiber optic transceivers and rack-mounted fiber optic transceivers. Desktop fiber optic transceiver is suitable for use on a single user, such as to meet the corridor in a single switch on the joint. Rack-mount (modular) fiber optic transceivers for multi-user aggregation, such as the center of the cell room must meet all the switches in the district of the Alliance.

Network management can be divided into managed fiber optic transceivers and fiber optic transceivers unmanaged.

Can be divided according to the type of management, unmanaged Ethernet optical transceiver: Plug and Play, electrical interfaces via hardware DIP switch settings mode. Managed Ethernet fiber optic transceivers: support carrier-grade network management.

Built-in power supply fiber optic transceivers according to the type of power can be divided into: built-in switching power supply for carrier-grade power; external power supply fiber optic transceivers: external transformer power multi-use civilian equipment. The advantage of the former is to be able to support a wide power supply voltage regulator, filter and equipment power protection, reducing external point of failure caused by mechanical contact; advantage of the latter is that the device is compact and cheap.

Points according to work, the full duplex mode (full duplex) is when the data transmission and reception of the shunt, respectively, transmitted by the two different transmission lines, the communication to both sides at the same time for sending and receiving operations, such a transfer way is full-duplex system, the full duplex mode without the need for the direction of the switch, therefore, no switching time delay generated by the operation.

The half-duplex mode (half duplex) is used with a transmission line, both for the reception and for transmission, although the data may be transmitted in both directions, but the communication parties can not simultaneously send and receive data, such transfer method is half-duplex system.

Using half-duplex mode, the communication system at each end of the transmitter and the receiver through the transmit / receive switch is transferred to the communication line, the direction of the switch, therefore, will produce a time delay.