Tag Archives: UPC connector

Common Mistakes in Fiber Optic Network Installation

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When install a fiber optic network, people may make some common mistakes, which were usually overlooked. In this article, I will list the most common ones. Hope to give you some guidance for your optical network installation.

1. Single Strand Fiber Device Must Be Used in Pairs

You will never buy two left shoes, but people often make a similar mistake when they’re working with Single Strand Fiber (SSF). Single strand fiber technology allows for the use of two independent wavelengths, such as 1310 and 1550 nm, on the same piece of cable. The most common single strand fiber device is Bi-Directional (BiDi) transceiver. Two BiDi transceiver must be matched correctly. One unit must be a 1310nm-TX/1550nm-RX transceiver (transmitting at 1310 nm, receiving at 1550 nm) and the other must be a 1550nm-TX/1310nm-RX transceiver (transmitting at 1550 nm, receiving at 1310 nm). The 1550nm-TX/1310nm-RX transceiver is more expensive than the 1310nm-TX/1550nm-RX transceiver, due to the cost of their more powerful lasers. So network engineers may hope to save money by installing a pair of 1310nm-TX/1550nm-RX transceivers. But, like mismatched shoes, it doesn’t work.

single-strand-fiber

2. Don’t Use Single-Mode Fiber over Multimode Fiber

Some people may want to make use of legacy cabling or equipment from an older fiber installation to save cost. But keep in mind that single-mode and multimode fiber are usually incompatible. Multimode fiber uses cable with a relatively large core size, typically 62.5 microns (om2, om3 and om4), and 50 microns (om1) still used in some installations. The larger core size simplifies connections and allows for the use of less powerful, less expensive light sources.  But the light therefore tends to bounce around inside the core, which increases the modal dispersion. That limits multimode’s useful range to about 2 km. Single-mode fiber combines powerful lasers and cabling with a narrow core size of 9/125 microns to keep the light focused.  It has a range of up to 120 km, but it is also more expensive. If you tried to use single-mode fiber over a multimode fiber run.  The core size of the fiber cable would be far too large.  You’d get dropped packets and CRC errors.

single-mode-multimode-fiber

3. Understand All kinds of Fiber connectors First

Fiber optic transceivers use a variety of connectors, so make clear their differences before you begin ordering products for a fiber installation is necessary. SC (stick and click) is a square connector. ST (stick and twist) is a round, bayonet-type. LC, or the “Lucent Connector”, was developed by Lucent Technologies to address complaints that ST and SC were too bulky and too easy to dislodge. LC connectors look like a compact version of the SC connector. SFP (small form‐factor pluggable) transceivers usually use LC connector.  Less common connectors include MT-RJ and E2000.

st-lc-sc

4.Connector Links and Splice Times Also Affect 

Although single-mode fiber suffers from less signal loss per km than multimode, all fiber performance is affected by connectors and splices. The signal loss at a single connector or splice may seem insignificant. But as connectors and splices become more numerous signal loss will steadily increase. Typical loss factors would include 0.75 dB per connector, 1 dB per splice, 0.4 dB attenuation per km for single-mode fiber and 3.5 dB attenuation per km for multimode fiber.  Add a 3 dB margin for safety. The more splices and connectors you have in a segment, the greater the loss on the line.

5. Don’t Use APC connector with UPC Connector

Fiber connections may use Angle Polished Connectors (APC) or Ultra Polished Connectors (UPC), and they are not interchangeable. There are physical differences in the ferules at the end of the terminated fiber within the cable (shown in the figure below).  An APC ferrule end-face is polished at an 8° angle, while the UPC is polished at a 0° angle. If the angles are different, some of the light will fail to propagate, becoming connector or splice loss. UPC connectors are common in Ethernet network equipment like media converters, serial devices and fiber‐based switches. APC connectors are typical for FTTX and PON connections.  ISPs are increasingly using APC.

apc-upc-connector

6. Don’t Connect SFP to SFP+ Transceivers

Small Form Pluggable (SFP) transceivers are more expensive than fixed transceivers.  But they are hot swappable and their small form factor gives them additional flexibility. They’ll work with cages designed for any fiber type and their prices are steadily dropping.  So they have become very popular. Standard SFPs typically support speeds of 100 Mbps or 1 Gbps. XFP and SFP+ support 10 Gbps connections. SFP+ is smaller than XFP and allows for greater port density.  Though the size of SFP and SFP+ is the same, you can’t connect SFP+ to a device (SFP) that only supports 1 Gbps.

Related Article: Optical Module Maintenance Methods and Installation Tips

What’s the Difference Between UPC and APC Connector?

We usually hear about descriptions like “LC/UPC multimode duplex fiber optic patch cable”, or “ST/APC single-mode simplex fiber optic jumper”. What do these words UPC and APC connector mean? What’s the difference between them? This article may give some explanations to you.

What’s the Meaning of UPC and APC?

As we know, fiber optic cable assemblies are mainly with connectors and cables, so the fiber cable assembly name is related to the connector name. We call a cable LC fiber patch cable, because this cable is with LC fiber optic connector. Here the words UPC and APC are related only to the fiber optic connectors and have nothing to do with fiber optic cables.

Whenever a connector is installed on the end of fiber, loss is incurred. Some of this light loss is reflected directly back down the fiber towards the light source that generated it. These back reflections will damage the laser light sources and also disrupt the transmitted signal. To reduce back reflections, we can polish connector ferrules to different finishes. There are four types of connector ferrule polishing style in all. UPC and APC are two types of them. Among UPC stands for Ultra Physical Contact and APC is short for Angled Physical Contact.

Differences Between UPC and APC Connector

The main difference between UPC and APC connector is the fiber end face. UPC connectors are polished with no angle, but APC connectors feature a fiber end face that is polished at an 8-degree angle. With UPC connectors, any reflected light is reflected straight back towards the light source. However, the angled end face of the APC connector causes reflected light to reflect at an angle into the cladding versus straight back toward the source. This causes some differences in return loss. Therefore, UPC connector is usually required to have at least -50dB return loss or higher, while APC connector return loss should be -60dB or higher. In general, the higher the return loss the better the performance of the mating of two connectors. Besides the fiber end face, another more obvious difference is the color. Generally, UPC connectors are blue while APC connectors are green. The following figure picture shows the differences mentioned above intuitively.

UPC and APC Connector

Application Considerations of UPC and APC Connectors

There is no doubt that the optical performance of APC connectors is better than UPC connectors. In the current market, the APC connectors are widely used in applications such as FTTx, passive optical network (PON) and wavelength-division multiplexing (WDM) that are more sensitive to return loss. But besides optical performance, the cost and simplicity also should be taken into consideration. So it’s hard to say that one connector beats the other. In fact, whether you choose UPC or APC will depend on your particular need. With those applications that call for high precision optical fiber signaling, APC should be the first consideration, but less sensitive digital systems will perform equally well using UPC.

Fiberstore offers a variety of high speed fiber optic patch cables with LC, SC, ST, FC etc. connectors (UPC and APC polish). For more information about UPC and APC fiber optic connectors, please visit fs.com.

Related Article: 6 Steps Help to Choose Right Fiber Optic Patch Cable

Related Article: LC Fiber Connector, Adapter and Cable Assemblies

One Small Problem When We Choose the Fiber Patch Cable

There is a common phenomenon that people are always able to distinguish different types of interfaces easily after corresponding to the given pictures, but when we choose the fiber patch cable, such as the polishing type also confused them, it shows UPC or APC, also confused us, recently I finally understand it and share my ideas with you.

First we can look from the definition, the above are acronyms for the following:

    • UPC – Ultra Physical Contact
    • APC – Angled Physical Contact

Only from the words we can have a simple understanding of them, in order to have a deeper understanding, there i named a few examples for you. Usually when we hear about the description like “fiber patch lc apc lc upc”, “e2000 fc apc”, “sc apc to sc upc single mode 9 125 simplex fiber optic patch cord cable”, what do this words apc upc mean? Then we will give you explanations. In Fiberstore, We use different color to distinguish them, the blue is UPC connector and the green is APC connector, shown as the figure.

In fact, it stands for the polish style of fiber optic core and connect the copper connector of copper cable as medium, and we need to know that the connections between the fiber optic connector and the ceramic core. Different fiber optic connector ring’s size, length and polished style is different, different polish of the fiber optic connector rings result in different performance, mainly on the back reflection. Generally, UPC is 50dB or higher and APC is 60dB or higher. All insertion loss of that they should be less than 0.3dB and the lower insertion loss is, the better performance they have, it is the reason why UPC connector is more widespread than APC. At the same time, there is a point we need to pay attention to, we all know that fiber optic cables can be divided into single mode and multimode fiber cables, but single mode fiber optic cables can be with UPC or APC polished connectors, while multimode fibers are not made with APC connectors. When we talk about the insertion loss, fiber optic attenuators have to be mentioned, it also has the diffent db to choose, as for the more knowledge about it, please always pay close attention to.

Fiberstore, you know, it offers kinds of fiber cables to choose, the different connector series all available for UPC/APC version, and we can also provide SM, MM, OM3 cables, simplex and duplex option, 0.9mm, 2.0 mm, 3.0mm cable diameter for choose, as for the fiber length, it can be customized according to your requirements.

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