The Mighty PoE

Media converters play myriad roles in today’s centric world

• By Frank (Skip) Haight
• Oct 01, 2019

The lowly media converter—the mainstream definition was always an electrical to optical Ethernet transmission device. Traditionally, it was considered a device used to convert from copper media to an optical fiber media and then back to copper, usually to send the data longer distances than the standard copper cabling can handle. But in today’s IP-centric world, media converters work on lots of different types of media.

The three that this article discusses are fiber optic media converters, extended distance media converters, and wireless media converters, all of which are transmitting an Ethernet signal.

The Ethernet Band

Here’s a graphical example of each type. Since all of them are transmitting Ethernet, they are all converting from a standard copper CAT5 or 6 cable, which has a limitation of 100 meters, or 328 feet. An optical fiber media converter converts to a fiber optic cable and then back.

Although an extended distance Ethernet media converter stays on copper cabling, it’s converting from a standard CAT 5 or 6 to a non-standard copper cable, such as a coaxial cable or an unshielded twisted pair cable, and then back to a standard cable. A wireless Ethernet media converter works the same way as the above types but it’s converting the Ethernet to a radio frequency to be transmitted through the air.

This article is to help you in selecting media converters that fit your application, so here are some important considerations. Many applications are outdoors and not in climate-controlled environments. Electronics don’t like to be cold or wet so a harsh environment requires a hardened product that can withstand extreme temperatures, condensation, transient voltages and other environmental factors. A lifetime warranty on all hardened products means the product will work now and as long as long as it’s installed.

Because there are so many factors to consider when selecting a media converter for a harsh environment, it’s important that you select a good partner to help pick an appropriate product. Fiber optic media converters. The number one benefit with this type is the long distances they can carry an Ethernet signal. Standard copper cat 6 cables only carry the signal 100m, but a fiber-optic media converter can extend that out over 100 km or more!

The second most common reason for using a fiber-optic media converter is to isolate the devices in an outside location from lightning or other electromagnetic interference. Optical fiber does not conduct electricity so any lightning strike or EMI will be isolated to that location and not a carry back to the headend. These are often used for very short runs in lightning prone regions or industrial locations.

Make the Right Choice

So how do you choose the right fiber-optic media converter? They come in lots of different types so here are options you have available to you. The first question is whether you need a fixed optic version or a unit that uses a small form factor pluggable, or SFP, that slides into the electronic unit and acts as your fiber optic transmission and receiving piece.

Next, figure out what type of fiber will be used. There is multimode or single mode. Then conclude whether it will use one or two fibers to make the connection. Many systems used two fibers so that you can send data one way on the first fiber and then in the opposite direction on the second fiber. Also related to the physical cable that will be used is the type of connector on that fiber. There are ST, SC, and LC connectors, and here we have it shown as a dual LC connector for the duplex fiber.

Ethernet runs at different speeds, so you also have to decide what data speed you want running over that fiber. There is 100 Mb per second, 1000 Mb per second, also called gigabit, or multi rate media converters that allow you to slide in either a 100 or a 1000 Mb per second SFP for flexibility.

You also have to decide on the form factor for the media converter. They come in a mini size, a medium mini size, and a full size that would fit in a standard 19-inch electronics rack. These smaller units are good for fitting in small locations like enclosures or the mounting arms/back boxes of IP cameras. The full size variants can be shelf or wall-mounted, or slid in to a 14 slot card cage with no modifications.

Consider All Options

The last option to consider is whether you need power over Ethernet at the remote location for your camera or other IP device. ComNet has options for 15 Watts, 30 W, or even 60 W for the outdoor rated IP PTZ cameras. And of course, all units ship with the correct power supply.

One application to note to consider with fiber-optic media converters is pairing appropriate units. When using just one fiber between the transmitter and the receiver you should pair an A unit with a B unit. The model number will tell you which it is. When you are using a duplex fiber optic cable between the transmitter and receiver, both units have the same model number.

Let’s examine extended distance Ethernet media converters. The main reason installations use them is a retrofit application where are you are moving from an analog camera infrastructure to an IP camera infrastructure. These media converters allow you to use the existing coax cable or UTP cable and now run Ethernet on it instead of the analog signal, and it can represent a huge cost savings versus pulling out the existing cabling.

The second most common benefit is being able to send an IP signal much farther than the standard hundred meters over cat six without having to switch to more expensive optical fiber cabling and optical fiber media converters. Many extended distance Ethernet media converters can transmit an IP signal over 2,000 feet.

The third benefit is a good reason installers choose this type of media converter. Pass-through PoE allows one power source, like a POE switch, power all devices on the line. Power is transmitted from the PoE switch, powering both of the media converters and also passing power up to the camera at the end of the line. This makes for a much quicker installation and means you don’t need to worry about finding power at the camera location.

Please note that the amount of POE you need at the end of the line will affect the distances you can successfully travel over any copper cable, so please consult our data sheets for specific limitations. Although ComNet has several product lines that perform this media conversion, our most comprehensive and popular segment is Copperline® distance extending media converters. It comes in 15- and 30-Watt models, various useful form factors, five different ways to power the modules, and 1 to 16 channel units.

Consider the Expense

Last in the series of media converters are wireless Ethernet media converters. This is a little different in that we are converting the binary code of Ethernet from an electronic signal to a radio frequency signal and then back again. The number one reason people use wireless is, so the cabling infrastructure necessary to carry the signal is not required. Trenching for new cabling is very expensive, complicated, and difficult to accomplish in many environments. This all represents a huge cost savings by using wireless transmission methods. The second big benefit is the speed of deployment. If you have power on site, the installation of a wireless Ethernet media converter can be very quick and effective.

This application is a simple point-to-point solution. The Net- Wave NWK 11/M and NWK1 kits include everything needed to set up a wireless link. The kits are preconfigured in the factory and MAC locked so that installation on the bench or in the field is simple, quick, and reliable. These preconfigured kits have allowed installers with no previous experience using Radio frequency products to successfully implement a wireless Ethernet media converter solution.

Since many of these applications are intended to be used in harsh environments, it is imperative that you select a product that can handle extreme temperatures and other environmental factors. In addition, it’s important to work with a company that has expertise in all types of Ethernet media conversion and can work with you to determine what solutions are best suited for your application.

This article originally appeared in the October 2019 issue of Security Today.