Technicians face the challenge of providing CCTV installations that meet their customers’ current and future needs. By understanding the trends and some simple installation techniques, you will be able to provide your customers with superior service.
Industry trends indicate that the capabilities of advanced IP-based systems will be driving a migration to IP-based cameras. To prepare for these changes, you need to know how to install an analog camera in a way that allows simple migration to an IP camera without having to completely rewire. Since wiring is often a significant expense in the initial installation, it’s prudent to use as much of the existing cable as possible for new installations.
For many years, coaxial cable has been the standard for installing CCTV. Cable selection was easy. Technicians just needed to understand the distance between the camera and the control center or monitoring point. However, complexity increased with the introduction of the pan-tilt-zoom (PTZ) cameras and their associated control circuits. But even this design condition rarely presented a cable selection challenge.
Now, with the advent of IP cameras, distance is becoming a concern. The standard allowable distance for Ethernet connectivity is 328 feet. Initially, this may appear to be a significant limiting factor for CCTV installations. However, in actuality, it provides a basis for truly future proofing your installations, whether they are analog or digital.
For IP camera installations, the network architecture defines the cabling requirements. As shown in Figure 1, a patch cable connects the camera to the network wiring. Category 5e or Category 6 unshielded twisted pair (UTP) cable connects to a patch panel in the telecommunications room. The cable length from the jack to the patch panel is limited to 295 feet. Since 328 feet is allowed for the entire channel, there’s an additional 33 feet for patch cable at either end of the cable run.
Additionally, the telecommunications room contains an electronic device known as a data switch that receives many inputs from devices connected to wall jacks throughout an area. Using electronics, the data switch manages the input signals and multiplexes them together on a single output connected to the network backbone. A typical network backbone uses fiber optic cable to transmit the data back to a data center. Data switches manage data traffic according to specific protocols, most commonly TCP/IP. The use of standards, such as those created by IEEE and TIA, has made the design and implementation of a data network a highly reliable utility.
Using the standards set in place for data cabling, you can install an analog camera today and still provide a viable path for future upgrades. When it is time to replace an analog camera with an IP camera, you simply change the connection in the telecommunications room to connect the camera to a data switch.
Figure 2 illustrates the components of an analog system utilizing standard network cabling techniques. Since the coaxial and UTP have different electrical characteristics, a converter is required. This device converts the 75ohm coaxial electrical characteristics to match the electrical characteristics of 100 ohm UTP.
In addition to the impedance mismatch between the cables, you must consider the types of signals. By design, coaxial transmits an unbalanced ground referenced signal while the UTP transmits a balanced signal without a ground reference. The conversion from the balanced to unbalanced signal is provided by a device called a BALUN (Balanced Unbalanced).
Typically, high-performance BALUNS are referred to as transceivers. The primary difference in the quality of BALUNS is reflected in the signal-to-noise ratio and the ability of the device to withstand a surge voltage. Low-cost devices can inject enough noise into the signal that the picture quality suffers. When used with motion video detection recorders, the high noise level can increase the recording usage and possibly eat into available bandwidth.