AT Attachment with Packet Interface Extension

　　As mentioned in the previous sections, ATA was originally designed for, and worked only with hard disks and devices that could emulate them. The introduction of ATAPI (ATA Packet Interface) by a group called the Small Form Factor committee (SFF) allowed ATA to be used for a variety of other devices that require functions beyond those necessary for hard disks. For example, any removable media device needs a media eject command, and a way for the host to determine whether the media is present, and these were not provided in the ATA protocol.

　　The Small Form Factor committee approached this problem by defining ATAPI, the ATA Packet Interface. ATAPI is actually a protocol allowing the ATA interface to carry SCSI commands and responses; therefore all ATAPI devices are actually speaking SCSI other than at the electrical interface. In fact, some early ATAPI devices were simply SCSI devices with an ATA/ATAPI to SCSI protocol converter added on. The SCSI commands and responses are embedded in packets (hence ATA Packet Interface) for transmission on the ATA cable. This allows any device class for which a SCSI command set has been defined to be interfaced via ATA/ATAPI.

　　ATAPI devices are also speaking ATA, as the ATA physical interface and protocol are still being used to send the packets. On the other hand, ATA hard drives and solid state drives do not use ATAPI.

　　ATAPI devices include CD-ROM and DVD-ROM drives, tape drives, and large-capacity floppy drives such as the Zip drive and SuperDisk drive.

　　The SCSI commands and responses used by each class of ATAPI device (CD-ROM, tape, etc.) are described in other documents or specifications specific to those device classes and are not within ATA/ATAPI or the T13 committee's purview. One commonly used set is defined in the MMC SCSI command set.

　　ATAPI was adopted as part of ATA in INCITS 317-1998, AT Attachment with Packet Interface Extension (ATA/ATAPI-4).

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Asymptotic bandwidth

　　The asymptotic bandwidth for a network is the measure of useful throughput, when the packet size approaches infinity.

　　Asymptotic bandwidths are usually estimated by sending a number of very large messages through the network, measuring the end-to-end throughput. As other bandwidths, the asymptotic bandwidth is measured in multiples of bits/second, e.g. megabits per second, etc.
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A STAR, Alcatel-Lucent prepare silicon photonics device library

　　The Institute of Microelectronics (IME), part of Singapore’s Agency for Science Technology and Research (A*STAR), has big plans to commercialize silicon photonics.

　　To make the plan a reality, IME has partnered with semiconductor foundry GlobalFoundries Inc. and equipment maker Alcatel-Lucent. The trio say they will bring innovative silicon component designs from research stage to commercial fabrication readiness within the next few years.

　　The new service will allow photonics developers to create new optical products out of silicon. They will be offered a library of building blocks consisting of silicon photonics device designs with the requisite process control monitors (PCMs) and process design kits (PDKs).

　　These photonic devices ; ranging from next-generation high-speed optical modulators, germanium photo-detectors, waveguides, and other common photonic circuits found in networking equipment ' have been developed as part of IMEs silicon photonics program. Further enhancements to the chips were enabled through strategic collaboration with Bell Laboratories, the R&D arm of Alcatel Lucent (see “IME, Alcatel-Lucent to collaborate on silicon photonics).

　　Silicon photonics enables manufacturers to integrate optical functions in silicon wafers, just as electronic devices are today, thus enabling them to take advantage of the infrastructure and R&D knowhow of silicon manufacturing accrued over the past 40 years. The result should be a dramatic reduction in cost of manufacturing photonic devices, sidestepping one of the main obstacles that has hindered their widespread adoption.

　　This milestone reflects the rapidly growing commercial significance of silicon photonics, said Prof. Dim-Lee Kwong, the executive director of IME. IME will continue to enhance our silicon photonics technology platform and work with our strategic partners to bring the benefits of silicon photonics to the industry worldwide.

　　I'm delighted that IME and GlobalFoundries are working with Bell Labs to accelerate the development of the exciting silicon photonics technology, which holds such promise for use in communication systems, said Alice White, chief scientist, Alcatel-Lucent Bell Labs. Bell Labs has been actively engaging leading microelectronics research institutes in silicon photonics research ' it is exciting to see these efforts moving forward into the commercial realm.

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Certifying Fiber Optics

A good quality of fiber optic networks is very important for the healthy of the critical networks especially for business use. For a network administrator, it is very necessary to known how well the invested fiber cabling network performed and how to solve problems at the first time they occur. Fiber optics certification has experienced a development from Tier 1, the Fiber Optics Certification Basic to Tier 2 fiber certification, that extended Tier 1 with an Optical Time Domain Reflectometer (OTDR).

The Tier 1 tests are attenuation (insertion loss), length and polarit, the complete Tier 1 fiber certification is required in all fiber optic cabling links. During the Tier 1 testing, each fiber
link is measured for attenuation and results are documented. This test ensures that the fiber link exhibits less loss than the maximum allowable loss budget for the immediate application. This CertiFiber is one handheld tester that quickly and easily certifies multimode networks. One button measures fiber length and optical loss on two fibers at two wavelengths, computes the optical loss budget, compares the results to the selected industry standard and provides an instant PASS or FAIL indication. By Tier 1 testing, the invisible events are hardly to locate.
Tier2 is the extended Tier 1 with the application of an additional tool, OTDR, which is used to trace each fiber link. An OTDR trace is a graphical signature of a fiber’s attenuation along its
length. You can gain insight into the performance of the link components such as fiber optic cable, connectors and splices and the quality of the installation by examining non-uniformities in the trace. This fiber test certifies that the workmanship and quality of the installation meets the design and warrantee specifications for current and future applications. An obvious advantage of using OTDR is that is helps detect the invisible events that may happened when conducting only loss/length (tier 1) testing, which is regarded as a complete fiber certification.
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What is Optical Time-domain Reflectometer Used for

Optical Time-domain Reflectometer is the full name of OTDR. In fiber tester fields, it is a very important and common optoelectronic instrument used for certifying and characterizing the optical fibers. During its working process, the optical time domain reflectmeter send a series of fiber optic pulses into the fiber cable, the fiber signal light will be scattered back and reflected back from points along the fibers. because of the fiberglass attribute, fiber joint point or fiber break. The strength of the return pulses is measured and integrated as a function of time, and is plotted as a function of fiber length. By this way, the OTDR can detect the Fiber Optic Cable length, fiber optic cable overall attenuation and locate the break point. In the following text, we will introduce the two major function of the optical time domain reflectmeter.
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Filter-based Wavelength Division Multiplexer

FTTX Filter WDM module is based on Thin Film Filter (TFF) technology. The Filter-Based WDM is extensively used in EDFA, Raman amplifiers, WDM networks and fiber optics instrumentation. The FWDM series is based on environmentally stable Thin Film Filters technology. The device combines or separates light at different wavelengths in a wide wavelength range. They offer very low insertion loss, low polarization dependence, high isolation and excellent environmental stability. In 10gmodule, Filter-Based WDM product family covers following wavelength windows commonly used in optical fiber systems: 1310/1550nm (for WDM or DWDM optical communications), 1480/1550nm (for high-power DWDM optical amplifier and EDFA), 1510/1550nm (for DWDM multi-channel optical networks) and 980/1550nm (for high performance DWDM optical amplifier and EDFA) and 1310/1490/1550nm (for PON, FTTX and test instrument).
1310/1490/1550 FTTX FWDM is based on filter based platform for optical device. This multiplexer features ultra low loss, high isolation, and high reliability.
10gmodule 1490/1310/1550nm FTTH FWDM can realize the multiplexing and de-multiplexing of two communication signal 1490/1310 and 1550nm. It can expand the capacity of a single fiber to achieve bidirectional communication, so that widely used in optical network upgrade and expansion, or introduce new comprehensive business etc.
As you might know, GEPON system itself works on 1310/1490, so CATV signal here is delivered over same fiber using 1550nm, and FWDM is a place where all this get’s “mixed”.
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The World Of Fiber Optics

The principle of fiber optics are based on transmission of data by means of light. Fiber optics emerged and grew into more advanced phase due to requirement from radio and telephone engineers. These engineers required more bandwidth for data transmission. Therefor these engineers had been looking out for a medium to transmit data in more reliable and faster form rather than copper cables.
Fiber optics had attracted some attention because they were analogous in theory to plastic dielectric waveguides used in certain microwave applications. Finally a technology evolved that used glass or plastic threads to transmit data. Cables involved in fiber optics contain several bundles of glass threads which are capable of transmitting data in modulated form.
With the start of fiber optics and Fiber Optic Cables data started to transfer faster as fiber optic cables have greater bandwidth than metal cables and are more resistive to external interference. Lighter and thinner fiber optic cables readily transfer data in digital form rather than analogue form. This technology is most useful in computer industry which now forms an integral part of telephone, our mission is to save shoppers time, money by bringing together everything that's needed to buy a fiber optic splitter radio and television industry.
Fiber optics yield distortion free data transmission in digital form. The audio waves transmitted via principle of fiber optics deliver accurate signal transfer. Fiber optics is also useful in automotive and transportation industry. Traffic lights, the new MIPP is a termination Patch panel that need to be connected to active equipment. organized and scrutinized highway traffic control, explains what is a optical fiber pigtail, fiber pigtail color codes are some of the benefits of application of fiber opticons in the transportation mechanism.
The use of lasers in fiber optics is an important milestone in the technical field. Because of their capability for higher modulation frequency, lasers were identified as an important means of carrying information. In fiber optic technology, transmitters comprise lasers and modulators. Lasers help to inject a signal into the fiber. Lasers create the light and the modulator changes the power of the laser light to combine the data to be transmitted.
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