All products that are powered by electricity also emit electromagnetic energy in the form of radio frequency or RF frequency emissions. These signals generally fall in the AM/FM radio range and can be measured with any RF signal detector. The problem is that these frequencies disturb other equipment in the area, causing interference. In video surveillance situations, it could be a loss of image quality on your cameras or monitors. Other nearby devices may also be affected.
In order for these devices to work in an environment, they must be electromagnetically compatible (EMC) so that they will not disturb or disrupt nearby equipment. For EMC to work, it has two elements, emissions from RF signals and immunity from RF signals. Immunity is the ability of any electronic product to tolerate the introduction of electrical energy from nearby electronic products. You must consider both emissions and immunity when setting up a video surveillance network.
The biggest cause of emissions in a network camera deployment would be using UTP or unshielded twisted pair cables to connect cameras near RF emissions, instead of shielded twisted pair (STP) cables. The difference between the two is that the STP version is an FCC Class B product designed for home use, which will have higher RF emission requirements. UTP is an FCC Class A rated product with lower emission requirements, which means higher emission rates that will cause interference.
The main problem is when you run the UTP in an environment that has other electrical devices like lighting, motors, or other electronic devices that emit RF signals. For example, placing a UTP along or inside a conduit with a 12 or 24 volt power line to power a light. In this case, you’ll want to use STP cable, which will help block emissions from the power line.
However, when you’re just connecting a cable to a camera and there’s nothing nearby, there’s no reason you couldn’t use a UTP cable, since there’s nothing nearby that is emitting electromagnetic signals. Let’s look at the advantages and disadvantages of STP cables.
The advantage of shielded twisted pair cable is that it blocks radio frequency emissions so you have fewer interference problems, resulting in better video quality.
The disadvantages are that it is more expensive and less flexible, so installations can be more difficult and will cost more.
Since you don’t really have to run STP on every network camera, it shouldn’t be a big deal or expense. Unless you see that you have certain camera cables that could be a problem with other nearby electronics, for the most part, you don’t need to run STP on every camera. Instead, you can run the UTP cables for the rest of your surveillance system and save the STP for those other areas.
Making sure you are shielding your video feeds in areas that have high RF emissions is critical to a successful network camera deployment so that all cameras can be viewed and results recorded for future use.