It has been highlighted again & again on this blog that performance of a CCTV Security Camera is not something which is totally dependent on the camera itself, which means, you cannot give 100 % credit to your favorite camera for its best resolution, and on the other hand you cannot even blame it for the low performance .
The show of CCTV Security Camera System is a team effort and is run by various components/modules in it playing their part and contributing to its overall performance. One such module is communication channel deployed for taking signals from camera at one place to the central monitoring station. We already discussed various types of topology employed in a CCTV System in our previous post for the case when communication channel is optical fiber network for larger distances. But there is more to it. Depending on the distance to be covered, technical expertise, budget available, there are n number of communication channels that can be used to make a CCTV System work in a premises.
Usage of RG Cable in CCTV Security Surveillance:-
RG Cable is the most commonly used cable as a communication medium in CCTV Video Surveillance System. It is generally used for a small scale requirement and where the distances are comparatively lesser. If the distance between the camera and central monitoring station is more, then the system may not provide its best performance due to attenuation in the signal, inspite of best of the cameras being deployed.
RG as such stands for Radio Guide or Radio Grade and is a term that is used when sending radio frequency (RF) signals down a coaxial cable. This is a cable with 75 Ohm impedance, comes in several sizes with the most common types being RG- 179, RG-59, RG-6, RG-7, and RG-11. RG-179 and RG-59 are the most commonly used coaxial cables because they are small in diameter and easy to work with.
The cables like RG-11 and RG-6 have larger gauge conductors and are used for larger distances as there are less signal losses in these cables owing to its larger diameter.
Below is the distance chart for various RG cables used in CCTV Video Surveillance
Our standards are—–
RG 06 Co-axial cable-(For short run – 270 meters)
RG 59 Co-axial cable- (For short run – 200 meters)
RG 11 Co-axial cable-(For long run – 400 meters)
(After 400 meters use video amplifier or use optic fiber cable)
Use of CAT 5 and CAT 6 Cables for IP Cameras:
If the Cameras deployed are IP Cameras, and distances from Camera to PC ie central monitoring station is also less (less than 100m), Then CAT6 cables are best suited for the application. We have already discussed the Benefits of IP Cameras over Analogue CCTV Systems in certain applications. But when it comes to cabling and network configuring, IP Camera System may sound a bit complex initially.
First of all we cannot use CAT 6 (Category 6 )cables for larger distances (that does not mean we prefer Analogue System over IP System), and when it comes to increased distances, we may have to switch to optical fiber.
Optical Fiber Network for CCTV Video Surveillance:-
Optical Fiber is advantageous for larger distances in networking. Be it the network for our CCTV System, or any other IT application. Although it is costly at times as signals travel in optical form in the network, hence there will be need of media converters and light interface units to convert the digital electrical signals into optical signals and vice versa. But as the distances in this case for video signals can go up to and more than even 60 Kms – All networking, splicing and even trenching costs at times can be overlooked.
Types of Optical Fiber:-
The Fiber Cable is generally of two types:- Single Mode and Multi Mode. Single Mode is used for larger distances whereas Multi Mode for shorter distances. Cost and types of networking devices will also change accordingly looking at the compatibility issues.
Wireless Networks for CCTV Security System
Now this does not end here, as places where cabling is not possible, or we have applications like City Surveillance- There is one more communication medium available which is worth exploring – ie Wireless Communication. It also saves us from the hassles of time consuming activities like trenching, cabling.
Motorola is one of the leading players in this field, where a transmitter and receiver or a group of transceivers are used to build a wireless network among the cameras installed and central monitoring station. For better connectivity it has to be ensured in this type of networking that clear line of sight (LoS) is available between cameras and CMS. Although there are devices available in the market which operates even in Non Line of Sight conditions, but I do not recommend that to avoid lag in the system.
This is all for this post, please do let me know if you would like to add any other communication medium in the above list.