Introduction to CCTV - Online Video Trainingby Scott Oie, posted on Dec 05, 2009
Understanding the basics of CCTV is critical to designing and deploying high quality video surveillance systems. In this report, we cover 8 key fundamental areas of CCTV. We reference a series of videos from Pelco that provide strong coverage of these fundamentals.
The focus of this series is on traditional CCTV. To complement this, you should read guides on IP video surveillance. Two in-depth guides are available - Axis's Technical Guide to Network Video and Vivotek's IP Video Surveillance Handbook.
CCTV Camera Introduction
It is important to understand the functionality of a CCTV camera; specifically how an image is first captured through a lens, processed through an imager, and converted to a signal.
An example of a CCD image sensor is broken down by functionality. Although the video uses examples of CCD imagers, cameras may use a CMOS imager, increasingly common with IP cameras.
In addition, it is key to understand interlaced video functionality, interlaced standards, and composite video properties.
Types of CCTV Cameras
A security professional should be able to identify the type of camera to use in a specific application. Understanding technical specifications for Indoor, Outdoor, High Resolution, Low Light, and Special Application types of cameras will help in selecting the right hardware for the environment.
Camera Lens Selection
This video provides a visual representation of how a lens works.
Since the quality of an image depends on the amount of light that reaches a camera's image sensor, it is important to know and understand the F-Stop rating for a specific lens.
Understand the different lens formats, common focal lengths, and note the calculation for selecting a lens size.
It is important to understand the effect of different types of light can impact the perception of a video image. Understand the difference in light quality of natural light sources like the sun, moon, and starlight. In addition, note how different artificial light sources can change the color of objects in an output video image (a suspect wearing an orange jacket may look like a brown jacket in a recorded video).
Camera Features and Lighting
Know what the features of a camera includes and how these features are applicable in what lighting conditions to adjust the quality of an output image.
Camera features like Automatic Gain Control and Back light Compensation are set depending on the lighting environment it is placed in. Also, be aware of the environmental limitations of a camera that has an Electronic Shutter Speed.
Since the quality of an image is dependent on the amount of light that reaches a camera's image sensor, it is beneficial to understand the quality of the image sensor. Although the video uses a CCD image sensor as an example, some cameras may have a CMOS sensor. The two types of sensors have different manufacturing processes; therefore, the comparative image quality between CMOS and CCD sensors may differ. I encourage further investigation on the topic of CMOS vs. CCD.
In the past decade, video surveillance has seen 3 major recording systems: the VCR, DVR and NVR. The VCR records analog cameras to tape, the DVR records analog cameras to hard drives and the NVR records IP cameras to hard drives or network based storage. Increasingly popular are hybrid DVRs that combine DVR and NVR functionalities.
It is not common to consider a security VCR to integrate into a new security system. Use the VCR explanation in the video below as a comparative analysis to the features of a DVR.
Understand the process of how an analog signal gets converted to digital and stored. Also note the topic of DVR compression methods.
Note: with the growth in the use of IP video, the training is out of date since it does not mention NVRs.
Gaining a strong knowledge base of the previous topics is critical in putting together a successful system design. Effective system design can increase efficiency and cut costs; When performing a site survey, take time in examining the environment, understand the surveillance purpose, and factor the cost of the system.
With these fundamentals in mind, read our Video Surveillance Design Guide to review 7 key factors in designing systems.
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