Fiber Optically Smooth - The OTDR

The use of modern fiber optic test equipment can be used to help phone companies keep their networks operating without interference. When a long distance telephone line goes down, it's not the type of publicity phone companies revel in. Fiber optical technology continues to grow to ensure the dependability of phone companies to all their customers. In addition to the underlying stability and dependability of these networks, fiber optical measurement tools play a large role in keeping these networks operating smoothly. During installation, commissioning and maintenance, fiber optic cables, connectors and splices are routinely tested for flaws. These tests are done by using specialized test equipment such as fiber optic power meters, optical time domain reflectometers (OTDR), optical sources and optical attenuator's. These same instruments can be used to determine the basic system operating parameters such as signal levels, signal attenuation and bit error rate (BER) measurements. During installation and maintenance, it is important to view the continuity of the fiber optic link. This procedure can only be done by using the OTDR. An OTDR consists of a pulsed optical transmitter, an optical coupler and a photo diode-based receiver, signal-processing circuitry and display screen. By using the connectors and the adapters, the OTDR is connected to one end of an fiber optic cable. Its transmitter sends short-duration pulses along the cable that are back scattered by imperfections of the fiber optic itself (Raleigh scattering), or reflected from splices, connectors, breaks and fiber end (Fresnel reflections). The returned pulses are oriented through the fiber optic coupler to the receiver, where it measures the levels and the traveling time of the returned pulses. Loss and reflection values are shown on a display versus the location of these events, calculated with the traveling time and speed of light inside the fiber core. Locations of the loss and reflection value’s can be given with a 1-meter resolution. For the exact fault location, the values must be corrected, since they show the physical location along the fiber, while the fiber optic is actually twisted within the cable. Depending on the power level of the transmitter and the pulse width, OTDR's can reach distances of 50 km to 200km. Longer pulses, due to their higher energy level, are used to cover long-haul applications. Higher resolution, as necessary in short-haul applications, can only be achieved by shorter pulse widths. The measurement resolution describes how far apart two faults can occur and still be accurately measured. An OTDR is often used by phone companies to isolate breaks or faults within their operation, such as in areas of extreme signal loss within a cable. Resolving a break to within a meter or less narrows down the section of cable that must be replaced, saving expense and time for the service crew. As the OTDR also enables the measurement of the overall length of the fiber optic link, it’s results are often used as a base for the expense calculation of the installation company.

Fiber Optic Cable Otdr Basics

Fiber optic communication systems have become more of a challenge for network operators to strategically and promptly keep them running at top performance in order to meet intense demands for reliable services. Many operators will go through a rigorous fiber optic training course. As the fiber optic communication systems evolve, there become newer and more complex parameters to monitor, more links to install and maintain, and more expected disruptions to track down. A new function in the primary test tool for fiber optic cable plants is the Optical Time Domain Reflectometer, or OTDR. The OTDR is an instrument that uses the inner back scattering properties of an optical fiber to detect and categorize its condition by sending high power pulses of laser light down into the fiber and capture the light that is reflected back. This new tool is of great significance for fiber optic technicians. Fiber optic patch cables are another way to provide the correct amount of light. Software enhancements are reshaping OTDR testing with potent new data processing capabilities that allow even the least experienced operator to analyze the fiber optics quickly and completely, and to find subtle features easily. While OTDR concepts are basically simple, precise measurements can be complicated. Reflected fiber optical power is a tiny fraction (of basically one-millionth) of transmitted pulse power that eminently varies with wavelength, cable length, fiber optic backscatter co-efficient, along with splice and connector attributes. Measurement parameters of fiber optics under test have to be carefully selected based on mode, length and attenuation, in order to optimize fiber optic measurements with an older, manual OTDR. The optimal parameters for all fibers, in exception for the shortest optical fibers, vary in relation to the distance of the event from the instrument. The newest OTDR instruments integrate software programs that automatically detect and configure the optimum test parameters and show results in simple formats. Most fiber optic cables require multiple OTDR measurements by using different parameters to completely and accurately characterize their property ties. These types of tests can take more time than is acceptable during a network emergency or a lengthy commissioning process. When troubleshooting the close-range resolution versus long-range visibility, several sets of waveforms must be acquired by using different OTDR settings as often as necessary. After completing the first scan by using a short-duration optical pulse, the next scan will use a longer-duration optical pulse to provide additional optical power to test further along the optical fiber. Newer OTDR's incorporate built-in testing programs that automatically characterize the fiber optics in a sequential manner, starting from the instrument-to-fiber connection and working outward. Such programs automatically determine which parameters need to change, based on criteria like signal-to-noise-ratio, length, total loss and elapsed time. They may also increase the number of averages, change the filtering, or adjust the gain of the detection circuitry in order to optimize the test results for each specific cable segment. Many other software enhancements have been introduced to the acquisition , analysis and archiving of fiber optical test data, making the OTDR an even more valuable asset for technicians to meet the challenges of supporting fiber optic cable plants.

Using Fiber Patch Cables

Fiber patch cables are the backbone of the fiber optics industry. These fiber patch cables are strands of optically pure glass as thin as human hair. These cables carry information via mode of transmission of light. Short patch leads usually made with stranded wire are flexible patch cables. The fiber patch cables are used to plug one piece of equipment into another.

They have various uses in all kinds of industries. Fiber patch cables are used in medical imaging, mechanical engineering, LAN applications, cable TV networks, telephone lines, etc. Fiber patch cables have revolutionized the total network industry of telephones, cable, internet, audio applications, etc. The fiber patch cables offer accurate signal transfer which is totally distortion free. Thus due to these cables the audio or video transmission is completely distortion free and crystal clear. Since these fiber patch cables use light as a mode of transmission there is no hazard of electric interferences or any tampering.

Fiber patch cables are used to two nearby components with fiber connectors. Fiber patch cables come with their respective connectors. They can be an ideal and easy replacement of copper cables because they use the same RJ45 connector as copper patch cables.

Fiber patch cables are available in simplex, duplex, multimode, single mode with STST, STSC, SCSC connectors. Fiber patch cables are of two prominent types – single mode and multimode. Single mode fiber patch cables are used in long-distance high capacity voice applications like telephone transmission or long distance gigabit networking. These fiber patch cables can use 9/125 micron bulk fiber cables and connectors at both ends.

Multimode fiber patch cables are used in computer industry which is standard for data applications like local area network, wide area network, etc. Fiber patch cables in multimode are available in 50µm and 62.5µm. SC, ST, LC, FC, MT-RJ, E2000 and MU connectors have polished ceramic ferrules for precision and durability. The SC and LC duplex fiber patch cables come equipped with a clip to maintain polarity.

ST to ST fiber patch cable gives unlimited bandwidth at high speeds over long distances. These fiber patch cables are ideal for connections between fiber patch panels, hubs, switches, media converters and routers, etc. Fiber patch cables provide higher speeds and increased bandwidth, compared to conventional twisted-pair copper cable. These fiber patch cables are compatible with all standard fiber optic equipment and connectors. Ceramic connectors of these fiber patch cables ensure low signal loss and high reliability along with total immunity to electrical and electromagnetic interference.

Fiber patch cables are the most opted solution these days for the networking and broadcasting industry.

Choosing Fiber Optic Patch Panels

When surmounting trouble rises, an optic fiber technician must choose the most suitable patch panel for a particular situation. That technician must recognize that when it comes to easy installation, proper termination and long term maintenance, not all patch panels are created equally. Optic fiber is robust and therefore deserves some special treatment. For example: if a horizontal copper cable is damaged, one user will be affected. If a backbone fiber goes down, it can take a lot of users down with it. This is why using fully enclosed connecting hardware for optic fiber is crucial. This is where the technician must choose between using wall-mounted or rack-mounted hardware. The optic fiber density required will most likely influence the technicians choice between the wall-mounted and rack-mounted connectivity. Many technicians will choose to use fiber patch cables. Trust your technician to know what’s best.

Wall-mounted enclosures are suitable for up to 24 optic fibers, although with small form factors and high density connectors, can extend the fiber optic cable count to as many as 144. Wall-mount enclosures also offer the benefit of reduced floor space requirements. Rack-mounted optic fiber enclosures can be used with higher fabric counts or depending on the proximity to communications equipment, where rack-mounted optic fiber enclosures are preferable. 1U enclosures can handle up to 24 optic fiber cables with ST or SC connectors, or up to 48 optic fibers by using small form factor connectors. For extra protection, 2U to 4U enclosures can be used to handle up to 144 optic fiber connections.

A 12 fiber MPO connector can speed installation time and increase the concentration of connection hardware. The factory terminated and tested cassettes take care of breaking out the optic fibers from the MPO connectors to ST, SC, or MT-RJ connectors. The MPO cassettes can double the concentration that are possible in rack-mount enclosures - up to 72 optic fibers in a 1U enclosure and 288 optic fibers in a 4U enclosure - making these optic fibers perfectly fit to meet high density applications, such as data center’s and storage area networks.

Accessibility is a concern for long term maintenance when choosing a rack-mount enclosure. The 1U enclosures may have a an access panel to reach the rear optic fibers, while larger enclosures may have a removable rear cover with adequate room inside to make changes or perform repairs. Strain relief and loop management for incoming cables must be provided, nonetheless management devices should be small enough as to not interfere with access to the optic fibers. Cable management for patch cords should be provided on the front of the enclosure with clear front covers and labeling arranged to ease moves, adds and changes and by ensuring that port identification is not obscured by patch cords.

Since copper patch panels need to be strong enough not to flex too much as the cables are punched down. The rolled edges on the panel sheet metal stock help to make the panels rigid. Copper patch panels should provide 24 ports in a 1U height or 48 ports in a 2U height. It's very important to make sure that the modular jacks and circuit traces on the panels are protected from debris that can short out circuits. All cable management systems must be easy to use and maintain to avoid any potential problems.

A Brief Introduction To Fiber Optics Technology

Understanding how fiber optics are made and function for uses in everyday life is an intriguing work of art combined with science. Fiber optics has been fabricated from materials that transmit light and are made from a bundle of very thin glass or plastic fibers enclosed in a tube. One end is at a source of light and the other end is a camera lens, used to channel light and images around the bends and corners. Fiber optics have a highly transparent core of glass, or plastic encircled by a covering called "cladding". Light is stimulated through a source on one end of the fiber optic and as the light travels through the tube, the cladding is there to keep it all inside. A bundle of fiber optics may be bent or twisted without distorting the image, as the cladding is designed to reflect these lighting images from inside the surface. This fiber optic light source can carry light over mass distances, ranging from a few inches to over 100 miles.

There are two kinds of fiber optics. The single-mode fiber optic is used for high speed and long distance transmissions because they have extremely tiny cores and they accept light only along the axis of the fibers. Tiny lasers send light directly into the fiber optic where there are low-loss connectors used to join the fibers within the system without substantially degrading the light signal. Then there are multi-mode which have much larger cores and accept light from a variety of angles and can use more types of light sources. Multi-mode fiber optics also use less expensive connectors, but they cannot be used over long distances as with the single-mode fiber optics.

Fiber optics have a large variety of uses. Most common and widely used in communication systems, fiber optic communication systems have a variety of features that make it superior to the systems that use the traditional copper cables. The use of fiber optics with these systems use a larger information-carrying capacity where they are not hassled with electrical interference and require fewer amplifiers then the copper cable systems. Fiber optic communication systems are installed in large networks of fiber optic bundles all around the world and even under the oceans. Many fiber optic testers are available to provide you with the best fiber optic equipment.

In fiber optic communication systems, lasers are used to transmit messages in numeric code by flashing on and off at high speeds. This code can constitute a voice or an electronic file containing, text, numbers, or illustrations, all by using fiber optics. The light from many lasers are added together onto a single fiber optic enabling thousands of currents of data to pass through a single fiber optic cable at one time. This data will travel through the fiber optics and into interpreting devices to convert the messages back into the form of its original signals. Industries also use fiber optics to measure temperatures, pressure, acceleration and voltage, among an assortment of other uses.