Page 12 - Security Today, October 2019

The Mighty PoE Media converters play myriad roles in today’s centric world
By Frank (Skip) Haight
“The number one reason people use wireless is, so the cabling infrastructure necessary to carry tThe signal is not required.”
he lowly media converter—the mainstream defini- tion was always an electrical to optical Ethernet transmission device. Traditionally, it was consid- ered 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 cop- per 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 con- verters, 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 ex- treme 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 me- dia 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 iso- lated 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 avail- able 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 mul- timode 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 physi- cal 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 con- verter. 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 Eth- ernet 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 trans- mitter 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
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MEDIA CONVERTERS