Reusing Existing Coax Cabling (EoC) TutorialBy Ethan Ace, Published Feb 09, 2012, 12:00am EST
The coaxial cables which transmit most analog CCTV video can be reused when migrating to IP cameras. The technology to do so, most often referred to as Ethernet over Coax (or EoC), is mature and available from a variety of vendors. The challenge is: when should you use EoC and when should you simply pull new UTP cable? In this note, we examine the advantages and disadvantages of re-using coaxial cable.
There are a number of advantages to reusing existing cables. The most commonly cited is money saved versus pulling new cable. However, a number of other benefits exist for niche scenarios:
- No Cabling Costs: Since cable is already in place, there is no additional expense involved to pull new cable, install new conduits, cable supports or cable trays. There is no need to remove the existing cabling, as many end-users and code officials frown upon abandoning existing unused cables in place.
- Faster Installation Time and Deployment: An analog camera can be replaced with IP camera and online in less time than it would take to pull a new Cat 5e/6 cable.
- Minimal Impact to End User Operations: No business interruptions due to installers, ladders, open ceilings, or cabling spool boxes. There is no potential for damage to the customer’s facility and minimal jobsite clean-up.
- Extended Cable Distance: Ethernet using UTP cable is generally limited to a 100 meter distance, without the use of extenders, for IP data transmission. With converters, existing coaxial cabling can transmit IP video over more than a thousand feet of cable.
- Camera Power: Coaxial cabling, when used with converters, can also transmit PoE power to IP cameras without the need for a separate power supply at the camera location.
However, there are key disadvantages to reusing existing cable, as well. The most important is that converters are needed at each end and they can be expensive.
- Cable Converter Costs: Ethernet over coax converters cost, on average, $400-500 per camera/connection. Note that less expensive off-brand and consumer products are avaiable, which are generally not recommended for professional installation, as they generally lack the same data rates and features of professional models. UPDATE: The Altronix eBridge, a recent entrant to the EoC space, is available for much less than other options, selling online for about $200.
- Data Transmission Speed: Coaxial cable can generally only reach 10/100 Fast Ethernet speed as opposed to gigabit speeds which can be achieved with UTP cabling. However, 100 Mbps is usually more than enough bandwidth for a single SD or MP resolution IP camera.
- Cable Testing & Re-Terminating: It is generally a good idea to test the existing cabling prior to re-using it to make sure that it is functioning properly, terminated correctly, and not excessively spliced. Existing cabling may need to be re-terminated for maximum transmission quality.
- Warranty: Generally, most security integrators will not warranty existing cabling, whereas certified installers of copper Ethernet systems may offer warranties of ten to twenty years or longer, supported by the manufacturer.
Using Ethernet over Coax Converters
The installation of coax converters is pretty straightforward: at the camera end a small form factor media converter is installed in the camera housing, if space permits, or in an adjacent junction box. At the network switch location, another small form factor or rack mounted converter unit with a power supply is installed. The existing coaxial cable connects to one side of the converter and a UTP patch cable connects the other end to the camera or network switch. Many current genereation EoC converters transmit PoE power, in addition to data, via coax, eliminating the need for a power supply at the camera end. However, not all manufacturers provide this, so users should confirm this capability.
EoC Product Options
Coaxial converters are readily available in the marketplace. Comnet’s Copperline [link no longer available] and Veracity’s Highwire PowerStar [link no longer available] coax converters are commonly cited. Last year, NVT entered this market and this month, well-known power supply and video connectivity manufacturer Altronix has released their eBridge coax converters. All of these product lines have pros and cons, with some offering PoE over coax, multi-port units, and other capabilities.
Historically, the major drawback to using coax media converters has been their cost. With most manufacturers averaging $400+ per camera, this pricing was more normally more than the cost of running a new UTP cable, $150-250 on average. However, the Altronix eBridge has been released at a price point which makes it competitive with UTP cables.
Taking a sixteen-camera system as an example, we get the following numbers:
- 16 x Altronix eBridge: $3,200
- 16 x Other options: $6,400
- 16 x UTP drop: $2,400-4,000
If available, options which reduce hardware required at the head-end (NVT has a 4:1 transmitter/receiver ratio and Nitek offers 8- and 16-port options) will reduce these prices modestly. At shorter distances, running UTP cables is still likely less costly than the eBridge. However, reductions to disruption of business may make this difference palatable. Other EoC options, are more expensive than UTP in all but very specific cases, which we discuss below.
When to Use EoC
So, if EoC converters are more expensive in typical cases, when should they be used? Fundamentally, the decision to use EoC comes down to determining which applications will cost more to pull new cable than to deploy EoC converters. Historically, this has been limited to very specific cases, where building construction made cables too costly to install, or distances were beyond those UTP could serve.
However, with lower-cost products such as the eBridge available, EoC becomes a reasonable option for many more installations, as the $200 price tag is equal to or only modestly more than what a UTP drop would cost. Even very small systems may appreciate EoC in these cases, despite slightly higher price tags, simply because it reduces the amount of hours the integrator will be on-site, as well as the disruption to business. Since work only needs to be performed at the camera location and the head-end, dirt, debris, and interruptions are limited to these areas.
EoC options which provide power via the coaxial cable may also be considered for cameras which are beyond the 100m maximum distance allowed when using UTP. Typically, fiber-optic cables are used in these applications, further increasing costs over UTP. Parking lots, outbuildings, or warehouses may all be good candidates for EoC adapters, as less costly coax cable may be used, and power may be supplied up the coax with many adapters, eliminating the need for power at the far end which a fiber media converter would require.
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