Introduction of PC, UPC and APC Connector

When we choosing a LC connectors, you might hear descriptions like LC UPC polished fiber optic connector, or LC APC fiber optic connector. Or when you are choosing a ST fiber optic patch cable, you can find the description like ST/PC multimode fiber optic patch cable. What do PC, UPC, APC stand for? The following text will give the explanations.

PC (physical contact), UPC (ultra physical contact) and APC (angle physical contact) are the polish style of ferrules inside the fiber optic connectors. Unlike copper cables with copper wire in the connectors as connection media, fiber optic connectors are with ceramic ferrules for connection. The picture above shows the ferrule in fiber optic connector. Different fiber optic connectors has different ferrule size and length. Also their polish style might be different.

To better understand the why we have PC, UPC and APC, let’s start with the original fiber optic connector which has a flat-surface and is also known as flat connector (showed in the following picture). When two flat fiber connectors are mated, an air gap naturally forms between the two surfaces from small imperfections in the flat surfaces. The back reflection in flat connectors is about -14 dB or roughly 4%. To solve this problem, the PC connectors came into being.

In the PC connector, the two fibers meet, as they do with the flat connector, but the end faces are polished to be slightly curved or spherical. This eliminates the air gap and forces the fibers into contact. The back reflection is about -40 dB. The following picture shows two end faces of PC connectors.

UPC connector, usually has a blue-colored body, is an improvement to the PC connector with a better surface finish (as showed in the following picture) by an extended polishing. The back reflection of UPC connector is about -55 dB which lower than that of a standard PC connector. UPC connectors are often used in digital, CATV and telephony systems.

PC and UPC connectors have reliable, low insertion losses. However, their back reflection depends on the surface finish of the fiber. The better the fiber gain structure, the lower the back reflection. If the PC and UPC connectors are continually mated and remated, back reflection will degrade. An APC connector won’t have such problem. Its back reflection does not degrade with repeated matings.

APC connector usually has a green body with an end-face still curved but are angled at an industry-standard 8 degrees (showed in the above picture) which allows for even tight connections and smaller end-face radii. Thus any light that is redirected back towards the source is actually reflected out into the fiber cladding, again by virtue of the 8 degree angled end-face. APC ferrules offer return losses of -65dB. Some applications that are more sensitive to return loss than others that call for APC connectors, like FTTx and Radio Frequency (RF) applications. APC connectors are also commonly used in passive optical applfications due to the fact that many of these systems also use RF signals to deliver video.

PC, UPC or APC, which should be the choice of fiber optic connector? The answer is it depends. Choosing the appropriate connector for a fiber network depends on things such as, network design and function. This article is originally published in my blog （http://www.fiber-optic-cable-sale.com/）which is update weekly. You can follow this blog for more about optical communication

1000BASE-T—Upgrade Your LAN Over Copper Cable

During the deployment of bandwidth-intensive applications over local area networks (LANs), many factors should be considered, like the speed, the infrastructure, the transmission media, etc. One of the most important things is the cost. Many LANs already use CAT-5 cabling. Replace these cables with fiber optic cable might cost a lot. For some companies which might have tight budgets and must leverage their existing infrastructure, 1000BASE-T would be a nice and cost-effective way to upgrade their LAN.

What is 1000BASE-T?

1000BASE-T is Gigabit Ethernet that provides speeds of 1000 Mbps (1 gigabit is 1000 megabits per second) over four unshielded twisted pairs of cabling rated at Category 5/5e or better. 1000BASE-T specification allows a segment with a maximum length of 100 meters due to signal transmission limits, which can be used in data centers for server switching, LANs, for uplinks from desktop computer switches or directly to the desktop for broadband application. One of the advantages of 1000BASE-T is cost-effective.

A Cost-Effective Solution for Gigabit Ethernet

Fiber optic cables are gradually replacing copper cables in today’s telecommunication network. However, given the high cost of replacing copper cables with fiber optic cables and the low cost and good performances of 1000BASE-T, many companies might choose the 1000BASE-T system to upgrade their network and enjoy Gigabit Ethernet over copper cables. The following text illustrates the reasons why 1000BASE-T is one of the most cost-effective high-speed networking technology available.

• No need to replace copper cables with fiber optic cables—it is known that copper solutions have traditionally been lower than fiber-based solutions. As many companies still use Cat 5 twisted pairs, the replacing of copper into fiber optics will cost a lot of money and time. With the application of 1000BASE-T, companies can upgrades their local area network, data centers, etc. by using their existing copper cable place which would be time-saving and cost-saving.

• No need to change Ethernet equipment and infrastructure investments—if you replace all the copper cables into fiber optic cables, you would be forced to replace cabling located in walls, ceilings, or raised floors. And the equipment connected to the fiber links should also be updated. It would be time-consuming and high-cost task, which won’t be the best choice of some companies with tight budget or lacking of time. With 1000BASE-T, these problems would be solved easily. 1000BASE-T preserves Ethernet equipment and infrastructure investments, including the investment in the installed Category 5 cabling infrastructure.

• Flexible 100/1000 and 10/100/1000 connectivity—1000BASE-T support data rate ranging from 10 Mbps to 1000 Mbps. Flexible 100/1000 and 10/100/1000 connectivity will be offered and will enable the smooth migration of existing 10/1000 networks to 1000 Mbps-based networks. Used in conjunction with 1000BASE-T SFP transceivers, 1000BASE-T can provide highly cost-effective shared gigabit service. Various 1000BASE-T SFP transceiver modules that can enhance the performance of 1000BASE-T systems are being provided by current vendors.

1000BASE-T is a time-saving and cost-effective solution to upgrade the LANs to have Gigabit Ethernet. With the big advantage of cost-effective, 1000BASE-T are being widely applied. As technology advanced, various products are being provided to enhance the 1000BASE-T performances, like 1000BASE-T SFP transceivers. Fiberstore provides a wide range of telecommunication products including 1000BASE-T SFP transceivers and Category 5/5e products. You can visit Fiberstore for more detailed information about 1000BASE-T

Originally published in : http://www.fiber-optic-cable-sale.com/1000base-t-upgrade-your-lan-over-copper-cabling.html

Why Choose Direct Attach Cable in 40G/100G Migration?

Advance technologies like Big Data and Cloud which require high speed of data rate become more and more popular. To meet the ever growing need to high speed data transmission, many data centers are migrating from 10 GbE to 40 GbE or even 100 GbE. And some are considering about the migration, during which the cost is one of the most important factors to consider. Direct attach cable also known as DAC is a cost effective solution during the migration to 40GbE or 100GbE.

What Is Direct Attach Cable

A direct attach cable also known as DAC is usually a fixed assembly supporting high speed data that uses a small form-factor connector module as an optical transceiver on each end of a length of cable. With significant cost-saving and power-saving benefits, direct attach cable is now being widely used in data centers for short reach applications. It can be connected to switches, servers, routers, network work interface cards (NICs), Host Bus adapters (HBAs) providing high density and high data throughput.

Why Choose Direct Attach Cable

Direct attach cable with many significant benefits can satisfy the growing need for high speed data. The main benefits of direct attached cable are described in the following text.

Cost saving: the modules on the end of direct attach cable looks like optical transceivers. However, actually they very much different from optical transceiver. These small form-factor connector modules leave out the expensive optical lasers and some electronic components. That's the main reason why the DAC is much cheaper than optical transceiver. Direct attach cable in some case can be an alternative to optical transceivers as it eliminates the separable interface between transceiver module and optical cable. Thus, choosing DAC in some cases can save a lot of money as well as time.

Low power consumption: to identify the modules on the end and cable type to the Ethernet interface, in both active direct attach cable and passive direct attach cable a small electrical component is used, which is low cost and consumes very little power compared with optical transceiver.

Supporting high data rate: DAC can provide high speed I/O (input and output) data. The most commonly used DAC can support high data rate of 10 Gb/s and 40 Gb/s. However, as technologies advanced, some vendor can provide direct attached cable supporting 120 Gb/s, like 120G CXP Cables.

Meet small form-factor standards: the modules on each end of DAC meet small form-factor standards which means DAC inherits some advantages of the small form-factor module, like space saving. Some time there is no need to upgrade the equipment by using a DAC.

With various benefits like abilities in data transmission and cost saving, direct attach cable is becoming increasingly popular for short distance top-of-rack (ToR) and middle-of row (MoR) data center deployments. It's a cost-effective solution to 40G/100G migration. Currently direct attach cable are continuing to evolve to meet industry needs. Various types of directive attach cable are being provided. Fiberstore as a vendor of optical components provides DAC cable assemblies including 10G SFP+ Cables, 40G QSFP+ Cables, and 120G CXP Cables. For information please visit Fiberstore.

Originally published at: http://www.fiber-optic-cable-sale.com/why-choose-direct-attach-cable-in-40g-100g-migration.html

Optical Transceiver Selection Guide

As an important optical component being widely used in today’s optical network, optical transceiver has been developing rapidly. More and more vendors are providing various types of transceivers to meet the market calls. To select a matching transceiver for a given application and hardware is now an easy thing now. Many parameters should be considered. The following text is to provide the parameters should be considered during the selecting of the proper optical transceivers.

MSA (Multi-Source Agreement) Type

A transceiver is usually used to mechanically and electrically fit into a given switch and router. Transceiver MSAs define mechanical form factors including electric interface as well as power consumption and cable connector types. There are the following types of optical transceivers according to MSA: GBIC, XENPAK, X2, XFP, SNAP12, SFP, QSFP/QSFP+, CXP and CFP.

Protocol and Data Rate

As different switch or router supports different protocol and data rate. Before selecting the transceiver needed, make sure the protocol and data rate to be supported. The following provides the most common protocol and data rate types:

• Gigabit Ethernet: 1 GE/10GE/40GE/100GE
• Fiber Channel: 1GFC (1.25Gbps) / 2GFC / 4GFC / 8GFC / 16GFC
• SDH STM-1 (155Mbps) / STM-4 (622Mbps) / STM-16 (2.5Gbps / STM-64 (10Gbps)
• Multirate (155Mbps to 2.67Gbps)
• CPRI up to 6Gbps (for Video Transmission)

Transport Media

The most commonly used transport media are cooper, single mode fiber (SMF), Multimode fiber (MMF). Maker sure the transport media, before choosing an optical transceiver.

Transceiver “Color”

The colored transceiver commonly known as CWDM transceivers and DWDM transceivers. In CWDM or DWDM system, each channel uses a different “color” transceiver because each lambd represents a different color in the spectrum

Equipment Compatibility

In what switch or router is the transceiver supposed to work. Now the third party transceivers are being provided. If the equipment open for third party transceiver, then the third party transceiver could be an option. However, if not, the brand, model and firmware version must be known.

IEEE Descriptions

The functions of the optical transceivers are various, thus understand the IEEE descriptions of the optical transceivers can help to select the match one quickly. The following provided are the translation of IEEE descriptions:

• MM: multimode
• SM: single mode
• Base -T: “copper” SFP with electrical RJ45 interface
• SX: SFP 850nm, MM, grey, 1GE, approx. 500m
• LX: SFP 1310nm, SM, grey, 1GE, approx. 8km
• EX: SFP 1310nm, SM, grey, 1GE, approx. 40km
• ZX: SFP 1550nm, SM, grey, 1GE, approx. 70km
• CX4: "copper" XFP with electrical IB4x connector
• SR: SFP+ or XFP 850nm, MM, grey, 10GE, approx. 300m
• LR: SFP+ or XFP 1310nm, SM, grey, 10GE, approx. 10km
• ER: SFP+ or XFP 1550nm, SM, grey, 10GE, approx. 40km
• ZR: SFP+ or XFP 1550nm, SM, grey, 10GE, approx. 80km
• SR4: QSFP 850nm, MM, 40GE, approx. 100m
• SR10: CFP 850nm, MM, 100GE, approx. 100m
• LR4: CFP or QSFP 1310nm, SM, 40GE (CFP or QSFP) or 100GE, approx. 10km

Taking the above parameters into consideration, to select a match optical transceiver would be much easier and more quickly. Fiberstore, an professional optical components provider, offers a wide range of optical transceivers of high quality including SFP, SFP+, CWDM transceiver, DWDM transceivers, etc. For more information, you can visit Fiberstore.

Originally published at: http://www.fiber-optic-cable-sale.com/optical-transceiver-selection-guide.html