Tips on Selecting an Ethernet Media Converter

January 9, 2014 at 10:00 AM


L-com Industrial Ethernet Media Converter (DIN Rail mounting)

Fiber optic technology is taking the Ethernet networking world by storm. It is faster, completely resistant to EMI/RFI, and offers incredible distances between nodes.

 

But fiber is not quite ready for all LAN applications. In many cases it makes sense to keep a copper network intact and lay a fiber network over it. So, here we find a need in our industry for a device that will convert seamlessly between the fiber optic network and the copper network without loss of speed.

 

We call these devices Ethernet media converters.

 

 

Industrial vs. Commercial

 

Commercial Media Converters

The first consideration in finding the proper converter for your application is whether your Ethernet media converter will be installed in a commercial or industrial environment. A commercial environment would include a typical office or clean room, and an industrial environment includes places with dust, moisture, temperature variations, vibrations, and other complications.

 

We've gone over the differences between the two in regards to switches before, but the same rules apply for media converters. It is very important not to confuse industrial versus commercial converters. While an industrial Ethernet media converter can operate in a commercial environment, it costs more and generally supports features not commonly found in a commercial environment such as DC power. On the other hand, a commercial Ethernet media converter should not be used in an industrial environment as network downtime and system failure can occur.

 


Single mode vs. Multimode

 

Fiber Glass Types

There are two main "modes" for fiber optic cabling: single mode and multimode. L-com has a great tutorial and video with in-depth explanation. In general, a single mode system is more expensive, but also provides better signal strength over large distances (up to 100km or more).

 

Multimode is much more affordable and can be used in distances of up to 2km, depending on network speed and bandwidth. Again, don't confuse the two! If you are running multimode cable, you need a multimode Ethernet media converter; a single mode version will not work.

 


Fiber Optic Connector Types

 

 

Fiber optic cables have their own unique connector types. There's a good video explaining fiber connectors here. Unlike copper, fiber connectors are very difficult to install properly in the field, and there aren't many options for converting a connector type with a passive adapter (although L-com does carry ST-SC, ST-FC and LC-SC adapters, among others, on its fiber optic adapters page). It is best to match the connector type with the device so they can be easily connected and no extra loss is incurred.

 

Remember, L-com stocks hundreds of factory terminated fiber optic cables off-the-shelf. We can custom manufacture fiber cables without minimum order quantities and with very short lead times, so you don't need to re-terminate or adapt a mismatched cable.

 

 

Other Features

 

Before ordering your media converter, also consider things like mounting method (DIN rails, 19" racks or chassis, or just placed on a shelf), network speed (10/100/1000 Mbps), and how you will get power to the unit. A properly installed media converter can both future-proof and provide redundancy for your network for years to come!

 

Quick note: Installing Ethernet media converters may require other components as well, such as fiber optic cables, Ethernet cables, and racks and accessories.
 

Access Point (AP) Antenna Replacements

August 21, 2013 at 10:00 AM

 

Upgrading the antennas on your WiFi access point: How to determine the correct AP connector

 

Our technical support department often answers questions like: "How do I upgrade my access points' antennas?" or "How do I identify the type of connector on my WiFi access point or router?" There are a few simple steps to adding or replacing the antenna on your wireless product.

 

First you must check to see if the antennas on your access point are removable.

 

                               Front of an EnGenius wireless access point (AP) showing antennas behindBack of an EnGenius wireless access point (AP) showing antennas

Front and back of a WiFi Access Point showing removable rubber duck antennas installed

 

Back of an EnGenius wireless access point (AP) showing antennas removed

Back of a WiFi Access Point showing rubber duck antennas removed.

 

Next you should identify the type of connector the antenna jack is on the access point. One tip is to check with the manufacturer's website or user manual for your specific make and model listing for the antenna connector type. If you cannot find it on the manufacturer's web site, you can compare it with our common RF connector chart shown below.

 

Common RF Coaxial Connectors

 

Also, you may want to upgrade to a higher gain rubber duck antenna on your access point to increase the signal range and strength. View our 2.4 GHz Rubber Duck antenna selection.

 

Or you might want to connect your access point to an outside antenna. In this case you will need to connect a low loss coax pigtail cable to your access point and then to a longer antenna feeder cable to reach the outside antenna as illustrated below.

 

Illustration of low loss coax pigtail used to connect wireless AP to an antenna

Quick tip: If you need a new antenna, try L-com's Antenna Product Wizard to make your search easier. The wizard will walk you through three steps to identify antennas that match your criteria.

Tutorial on Coaxial Cabling

July 3, 2013 at 10:00 AM

 

 

 

Coax is one of the most venerable cabling standards having been developed for the US military over 50 years ago. Unlike some standards that were popular for a while and eventually became legacy, coaxial cabling is still very relevant and used in a lot of common applications. It is a robust and reliable cable type with no sign of going away any time soon.

 

 

 Types of Coax Cabling

 

As you can imagine, over the years that coax has been around, many variations have been designed for specific applications. We will talk about the Radio Guide (RG) styles and the low-loss styles that were made popular by Times Microwave's LMR® standard. Though there are many other coax options like mini coax, twinaxial and tri-axial, the applications for those have dwindled in recent years.

 

 

RG-style Coaxial Cable

 

The original Radio Guide standard called for a number followed by codes to determine specific aspects of the cable (such as jacket type, center conductor material, etc.). However, today many of the standards have become "soft" meaning that RG58B/U, for instance, may have very different characteristics from manufacturer to manufacturer.

 

Exposed view of a coaxial cable

Most RG numbers refer to cables made with specific diameters (as thicker diameters typically have lower attenuation over long lengths), shielding, jacket type, and dielectric type. The dielectric is important as it can control the "characteristic impedance" of the cable. In general, cables with a characteristic impedance of 50 Ohms are used in data and wireless network applications, and cables with a characteristic impedance of 75 Ohms are used in higher bandwidth audio/video applications.

 

The bottom line about RG-style coax cable: if you need to get a specific type for your application, you should include the characteristics of the cable with your request. The actual standard may have some variations that would make the off-the-shelf product unsuitable for some circumstances.

 

 

Low-loss Coaxial Cable

 

Low-loss cable is almost exclusively used in wireless applications. It is ideal for any antenna-to-radio setup, and is often used extensively in wireless system installations. Low loss cable is often referred to by its series number, such as 200-Series cable, which is usually a rough approximation of the diameter of the cable. The higher the number (ie, 400, 800, etc), the thicker and heavier the cable, and the less attenuation over the length. Because of this, higher series numbers are typically used in cases where the antenna is permanently installed at some distance from the radio. Lower series numbers are used in cases where the antenna is closer, especially in portable setups where the weight of the cable is important.

 

 

Connectors

 

There are a large variety of coaxial connectors, usually designated by a letter or combination of letters. Most coaxial connectors are round or hex shaped, and can come in screw-on, push-on, or twist-lock designs. Be extra careful if you need a connector that is called "reverse polarized" or preceded with the letters "RP". These connectors are similar to the regular polarity versions except that the gender of the connector is reversed, making it unable to mate unless it is with another RP style connector. For a complete list of coaxial connectors with large images, try this coaxial connector chart.

 
If you are in need of coax: L-com has carried RG style coax cable and assemblies for decades, and together with our vast collection of low-loss coax cables it is one of the most comprehensive in the industry.
 

Tutorial on Wireless Networking

June 12, 2013 at 10:00 AM

 

Wireless network antenna and devices

Entire cities and even countries are looking into ways to expand communications access for their residents as the Internet has shifted from a luxury to an imperative. The most promising solution: wireless networking.

 

Why? Wireless networking allows a non-physical (well, at least non-cabled) connection to a wireless LAN (WLAN) and onto the World Wide Web for users. So what are you waiting for? Cut the cord!

 

Be mindful of this though- issues such as network and band congestion, security, signal range and propagation, power demands, and more make WLANs tricky to implement for all but the most informed network engineers and IT professionals. Yet there's no stopping this technology in its rapid advance, with solutions such as distributed antenna systems (DAS) and MESH networks beginning to show promise. For you to get started, here's a basic wireless tutorial on terminology and concepts.

 


Wireless Standards

 

Radio frequency signals can take a lot of different forms, so in order for devices made by different manufacturers to communicate, the IEEE has provided several standards including the mainstay for wireless Ethernet: 802.11.

 

The 802.11 standard specifies the band and IP protocol used to transmit data, and provides guidelines to maximize the speed of transmission. 802.11a, for instance, uses the 5Ghz band and can typically transmit at speeds up to 54 Mbps in shorter ranges. 802.11b, 802.11g, 802.11n, and the new 802.11ac all use various methods to increase the speed and range. The latest IEEE wireless standard, 802.11ac boasts transmission speeds of up to 1 Gbps!

 

Each standard typically requires wireless routers, access points, and other transmission equipment to match its designation, though there are many that can operate in multiple standards (such as routers that are 802.11b/g/n compliant).

 


Wireless Bands

 

In attempt to maintain order within the entire radio frequency spectrum that is available to us, the FCC and other global communications standardization organizations have designated or set aside specific ranges of frequencies for specific uses. We call these "ISM bands". ISM stands for industrial, scientific and medical to denote where these frequencies are used.  ISM bands (specifically the 2.4 GHz and 5 GHz frequencies) are also used in commercial wireless networks. 

 

Typically access points, antennas, and amplifiers all use either the 2.4 GHz band, 5.8 GHz band, or both for WiFi. Other ISM bands have been set aside for things like cell phone use, RFID chips, emergency/municipal use, and military use.

 


Wireless Security

 

As mentioned previously, one of the big emerging issues with wireless networking is security. Without a physical cable that can be plugged and unplugged, the only method to control who can do what on a network is to build it into the software and protocol. That means it is critical to set up a wireless network with appropriate security measures and to be aware of the security status of any network you connect to.

 

For most small networks, methods such as WPA, WPA2, or WPA-PSK allow the safe identification of nodes that should be allowed on a network with passwords and other controls. Wireless routers can also use access passwords to allow administrators to adjust or update security features as required.

 
If you have questions about a wireless project or application, contact L-com's technical support line for a live response and expert advice!
 

A Tutorial on USB

May 22, 2013 at 10:00 AM

 

What exactly is USB?

USB Cable

 

USB stands for Universal Serial Bus and is a connectivity standard that transfers large amounts of data between devices. While it is far from the first standard designed for this purpose, the need for an effective method to transfer data between devices has become enormous due to the increase in portable and mobile devices.

 

The USB standard does just this, providing a universal method across different products and manufacturers. Other, "proprietary" standards exist, but they are often derivatives of USB with slight changes to the wiring or physical connector type.

 

 

Types of USB Cabling and Connectors

 

In the years since USB was first implemented, there have been three dominant versions, each providing faster data throughput than the last. USB 1.1, sometimes called "full-speed", can transfer data at about 12 Mbps. USB 2.0, which is currently the most common, operates at 480 Mbps. The latest standard, USB 3.0, operates at over 4.8 Gbps (about 10 times that of USB 2.0).

 

The most common USB connector types, Type A and Type B, are the same throughout the different versions. Though, other connector types such as the Mini B4, Mini B5, and Micro B are gaining popularity for their small size, which is preferred in smaller portable electronics such as mobile phones and tablets.

 

However, even if the connectors are similar, the cable itself must be constructed to the standard. For example, a USB 2.0 compliant cable could not pass 4.8 Gbps of data even if it were plugged into a USB 3.0 compliant device.

 

 

Why is USB so popular?

 

USB has several advantages over other standards that are used for the same purpose. First, it is a "hot connection", or has the ability to plug and unplug into a computer without causing it to freeze or causing programs to crash. USB is also uniquely designed to carry some low-voltage power which makes it capable of powering or charging devices that it is plugged into.

 

Also, though most applications only need standard USB cables, another advantage of USB is that it has the capability of specialization. Today we are seeing a rapid expansion of USB applications which require more specialized cabling- outdoor, wet or dusty environments, high-vibration situations, and places where special flame ratings, armor, or angled connectors are required. 

 

Check out our detailed USB tutorial here. Or, if you find yourself in this kind of special situation, try browsing L-com's USB product center for innovative solutions.

 

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