If you prefer to stay within the IEEE guidelines, the most cost-efficient way to lengthen the distance of twisted-pair cabling is to use Local Area Network (LAN) extenders. A LAN extender can boost an Ethernet signal an additional 330 feet. Some LAN extenders even support Power over Ethernet (PoE). You can chain up to three of these extenders in a row, enabling you to install a Class 1 (4 Watts) PoE network camera up to 1300 feet from your network switch or router. If you power the camera locally, you can chain up to seven units to achieve 2600 feet. Since copper wires can be negatively affected by lightening, it’s best to use extenders for indoor installations, such as the interior halls of a school or inside a parking garage.
Fiber optics: extending several miles
While fiber optics is more expensive than copper wiring, some fiber optics can transmit signals for several miles without degradation. This makes it a prime outdoors solution for malls and airports where the physical constraints of the location force installers to place switches and routers far beyond the standard 330 feet from the camera. With fiber, you get distance and quality. There are several drawbacks, however. First off is the additional cost of the cabling itself. Then, since it is a point-to-point communication, you also need to absorb the expense of installing transceivers on both ends of the wire to convert signals to and from twisted pair Ethernet. In addition, you can’t use a single PoE cable to both power the camera and transmit the data.
Wireless technology: extending many miles
Wireless technology offers several variations that can extend network camera connections over even greater distances than the three previously mentioned options. Here are a few of the more popular ones:
- 900 MHz. This is a point-to-point solution for operating over long distances. If you have a direct line of sight to the network camera, 900 MHz can transmit the signal up to 40 miles. The distance is considerably less when there isn’t a direct line of sight. Also, you need to be aware that the distance between the nodes will impact the bandwidth and the frame rate. One typical application for a 900 MHz connection is when just a few cameras are used to cover a large parking lot.
- Wireless mesh. Self-healing wireless mesh networks are popular when the area that has to be covered is large and requires many cameras. The nodes cover a broad area and provide overlapping and backup coverage through multiple transmission paths. A wireless broadband mesh generally operates at 4.9 GHz and can include hundreds of nodes, which makes it an ideal option for city center surveillance systems covering several square miles. The drawback is that it isn’t very economical for small system implementations.
Connecting an array of network cameras through wireless mesh nodes
can extend video coverage across many square miles.
- Cellular networks. With the rise in popularity of smart phones, data pipes for mobile networks continue to improve. With ever-greater capacity, this same bandwidth can also be used for video surveillance. Distance restriction is virtually unlimited, provided you are within the network of the cell phone operator. Using a wireless 3G modem, you can install a network camera quite cost-effectively – even on a remote highway far from the monitoring station. It’s a very flexible solution often used by police departments in covert, city-wide surveillance. Because it involves a cellular service provider like AT&T or Verizon, you need to budget for a monthly subscription fee for the network service.
Start thinking outside the box
Despite a common belief, distance should not be a limiting factor when choosing network over analog cameras. There are a number of viable options you can exploit, depending on your specific needs. And, unlike cabling analog cameras, distance does not affect image quality in network video. Nor are you limited to fixed lengths of 700 or 1200 feet like coax cable. Network surveillance can go any distance, often at a lower cost than coax. Consult with your surveillance vendor to determine which network option is the best choice for your specific installation.
About the author: Fredrik Nilsson is General Manager of the Americas for Axis Communications and author of the book Intelligent Network Video. He is a regular expert contributor on topics of networked video surveillance systems and cameras.