While cabling and transmission were at one point in time almost afterthoughts in video surveillance systems, in recent years they have come farther out of the shadows and are now fully recognized as the key foundational solutions they are. With this greater prominence has come more thoughtful consideration of the importance of getting things right through careful evaluation.
As always, distance is one of the primary factors in determining the proper cabling for a job, with coax, Cat 5e/6 and single-mode fiber only capable of transmitting video over finite distances (See “Distance Limits” on page 95). With the majority of transmission companies providing Power over Ethernet (PoE) capabilities, limits on the amount of power that can be provided to cameras and other devices go hand in hand with distance limitations.
Network Security
While the term cyber security tends to imply someone with a virtual intrusion into a network, it can also encompass physical breaches that provide access into a network — such as breaching cables to connect hardware or load malicious software.
“From a physical standpoint, integrators should make sure that the cable termination points and the cable runs are not visible and readily accessible by anyone,” says Speco Technologies’ David Choi.
When this isn’t possible, there is a relatively simple workaround.
“All cables not already within walls are contained within conduit, [which] can help secure against an unauthorized intercept connection,” says Aaron Starr of SecurityTronix.
For example, an IP camera installed at the edge can be disconnected with the intent of hacking into the network by connecting another IP device at that point. There are solutions on the market, such as ComNet’s Port Guardian, that protect against this possibility by detecting a disconnection and physically locking out that port from the network while simultaneously alerting administrators that a port has been compromised and disconnected.
“The port is, in effect, dead, and no connection to the network can be made,” says ComNet’s Skip Haight. “Upon notification of that action, the network administrator can investigate and reset the port when threats have been cleared.”
In addition to limiting physical access to cables, there is one other cable-related factor to consider for protecting networks.
“Integrators must stay aware and informed about all new and emerging threats against networks. One of these network threats is the potential for surge damage to critical systems from over-voltage events,” says Rich Mitchell, technical sales director, DITEK Corporation, Largo, Fla.
Case in point: most pass-through products are limited to approximately 15 watts, which may not be sufficient with today’s cameras and equipment. As IP-powered devices are developed, network transmission product manufacturers are constantly developing products to supply that power. The challenge now is the ever-increasing requirement for more delivered power, says Frank “Skip” Haight, director of marketing, ComNet, Danbury, Conn. “The first standard, IEE 802.3af, was for 15 watts; IEEE802.3at or PoE+ was for 30 watts; and now IEEE802.3bt 4PPoE or UPOE (Universal power over Ethernet, also known as PoE++) is for 60 watts. As these devices require more power for the use of PTZ and heaters, more power must be supplied.
“There are now IP cameras that need more than 15 watts to operate and require up to 30 watts to operate at their fullest capabilities,” he adds. “More IP devices are calling for even more power, and now PoE++.”
To overcome some of the challenges with PoE using some pass-through products, there are solutions, such as ComNet’s CopperLine products, that can act as power-sourcing equipment and provide up to 30 watts at distances greater than the typical 100 meters. Lower voltages can be sent even farther, up to 600 meters with a throughput of 100 Mbps.
“This capability alone gives the integrator an untold amount of flexibility and has the potential to reduce a very significant amount of cost from any project in terms of material cost and installation labor,” Haight says.
Fighting the Surge
Whether powered locally or over Ethernet cables, cameras and other devices can be prone to over-voltage events that can reduce their service life — requiring extensive repair and replacement costs on top of system downtime.
“Signal degradation can be caused by repeated exposure to surge energy, as can destruction and downtime,” says DITEK’s Rich Mitchell. “Users can avoid these hazards by applying proper surge protection. In order to increase the service life and help maintain uptime of a video power system, it is essential to provide a surge solution.”
When video power is provided as an individual circuit or from a power supply with multiple circuits, it is more convenient for an integrator to effectively manage video power requirements.
“Using a multiple-circuit video power supply makes it easier to apply surge protection for these circuits with a multiple-channel surge protective device,” Mitchell says.
At least in the near term, integrators should learn to work with what’s currently available rather than hoping for a new technology that could serve as a silver bullet for solving power and transmission challenges.
“Looking forward, I don’t believe there will be a new transmission medium invented, but what can be done over these different media is certainly going to advance — greater PoE distances and power over copper media; greater distances with less chance of interference from wireless; and greater bandwidth over distance with fiber,” Haight says. “All have their benefits, and integrators should not have any concerns about using one or all to solve transmission challenges they may face.”
Integrators who may be considering designing systems that approach the maximum limitations of the transmission medium should reconsider, as this will likely cause problems for customers’ systems.
“Power pushed to the limits of its capabilities and distances is a very common cause of video distortion or no video at all if the remaining power at the camera is below the bias forward threshold of the circuit,” says Aaron Starr, president of SecurityTronix, West Chester, Pa. “Many cameras may initially function outside their performance spec, only to distort or fail when power draw increases — for instance, during IR LED use in the dark.”
Distance Limits
Each of the three cable-based transmission methods brings its own pros and cons. Chief among these is the realistic distance over which video can be transmitted without degradation in the signal. Below are the generally accepted distance limitations — without using extenders, repeaters or baluns — associated with each, which must be taken into consideration when designing video surveillance systems.
Coax: 320 feet
Cat 5e/6 UTP: 1,600 feet
Single-mode fiber: 12.5 miles
CABLE QUALITY
Among the many potential causes of signal degradation or interruption are faulty terminations, poor quality cable and outside radio frequency or electrical interference, just to name a few. Therefore, one of the best things an integrator can do to ensure signal integrity is to use quality cabling as an important foundation for the infrastructure of any system.
“Routing cables away from sources of electromagnetic interference will help safeguard many common forms of signal degradation,” Starr says. “Running fiber optic cable will eliminate all sources of RF or EMI cables since the signals in a fiber are modulated to light frequencies, which are impervious to electronic signal frequencies.”
Integrators should do their homework and carefully evaluate the cables themselves before they are used in any surveillance project.
“Badly constructed cables or poor material quality cables can cause degradation,” says David Choi, product manager, Speco Technologies, Amityville, N.Y. “Also, getting close to the maximum distance can cause degradation as well. To avoid these issues, use good quality cables and give enough of a tolerance on the cable distance.”
When it comes to evaluating the quality of cables, Starr cautions that all cables are not created equal, despite what a manufacturer may claim. “More and more now there are several cables on the market that are sold as cat 5E or cat 6 that do not have a 100 percent pure copper conductor or the conductor is on the lower end of the specs’ conductor diameter,” he says. “These cables will restrict the typical maximum distances and it is important to evaluate the quality of what you are buying and not always trust the spec sheets.”
Generally speaking, it’s rare that any single project or application is going to be able to be completed with the use of a single medium. The likelihood that fiber optics, existing copper and even wireless is going to be needed is great. This fact should guide integrators in their design and deployment of video systems, Haight says.
“An integrator or dealer is going to have to be comfortable with all media and able to design a network that accomplishes everything the end user requires, and that might require a combination of fiber, copper and wireless,” he says.
