Video Surveillance & CCTV Introduction VideoBy John Honovich, Published Jan 04, 2009, 07:00pm EST
Getting started with video surveillance? This report covers the basic elements of video surveillance, walking you through each aspect including cameras, recorders, power, cabling and wireless.
In addition to the report, we are providing a high quality 30 minute video "Introduction to Video Surveillance," to help those who prefer to watch and learn. Two excerpts of the video are included in this report. The entire downloadable video only costs $9 USD.
CCTV vs Video Surveillance
Before you learn about any technical details, you should know that the field is called by a few names: CCTV, Video Surveillance and IP Video.
CCTV is the most traditional term and is still the preferred term in the UK and Commonwealth countries. The acronynm stands for Closed Circuit TV and signifies that the video is not publicly shared (i.e., it is closed unlike broadcast TV which is public). For better or worse, the term CCTV is increasingly viewed as referring to legacy, outdated technology.
Video surveillance is the most commonly used term in most of the world and the most accurate. Video is being used to surveill, that is to watch, the activities of an area. It does carry negative connotation for the general public because of the implication that people are being watched and privacy is being compromised.
IP Video is the newest term and reflects the new wave of technology that is being used in video surveillance / CCTV systems -- the use of computers to capture, record and transmit video.
VCR vs DVR
Almost everyone records the video from their surveillance cameras. The choices are actually similar to what you have for entertainment: VCRs, DVRs and NVRs.
A surprising number of people still talk about and search for VCRs (20% of Google searches for security recorders are still for VCRs).
However, in 2009, literally no one should be using a VCR because the costs are so close and the functionality is so superior for DVRs. Indeed, the new trend is away from DVRs and to NVRs.
PC vs Appliance
When choosing your recorder, you can use an appliance - that is a purpose built computer that has the video management software pre-loaded or you can buy your own PC and build it yourself.
At the very low end, using an existing PC can save you money. If you only want to record a few cameras and you do not want to spend much money, you can take the time to install an encoder card and load the software on your PC.
If you do not want to spend a lot of time, an appliance (for example, a DVR) is a simple way to quickly and simply connect cameras and have a video management system. This is a common choice in the range of 8 - 32 cameras.
All your equipment is going to need power. With the recorder, power is generally pretty simple because (1) its usually in a fixed position and (2) its usually near a power supply (like most desktop PCs). With cameras, providing power can be much trickier. Usually you will put cameras all over your facility and often outside of your facility as well. The challenge here is that most locations you want to put cameras are not close to power outlets. Making the issue worse, for both security and aesthetic reasons, you do not want to run a power cord from the camera down to a wall outlet.
The general solution is to run the power on a cable alongside the camera. Indeed, there are special cables made for just this (often called siamese to indicate cables for both power and video transmission). If you are installing multiple cameras, you can run these cables back to a headend and then use a camera power supply to terminate power for all cameras.
Most security cameras are powered by either 12V DC or 24V AC power sources. The vast majority of consumer security cameras (for use in home and small business security camera systems) utilize 12V DC power supplies. This low voltage is consumer friendly and the 12V DC power supply can simply be plugged into a standard wall socket. For large scale commercial systems 24V AC is very commonly used to power security cameras. The voltage drop over longer cable lengths (which can be hundreds of feet or more) is much less significant with 24V AC versus 12V DC.
If you are using IP cameras, you can run power and video transmission directly over your network cable (caled power over ethernet or PoE). However, you need a special switch or device to provide PoE and that adds about $30 more per camera.
Cables and Connectors
The vast majority of security cameras utilize a CCD (charge coupled device) composed of thousands of individual sensors that translate the incoming light into an electrical video signal. This video signal is then sent to a recording device or monitor where it is converted into video images. This video clip demonstrates some of the basics of CCD chips:
Size of Camera Chips
The three most common CCD chip sizes used in security cameras are 1/4", 1/3" and 1/2". In general, for a given quality of chip, the larger the chip size, the more area available for light gathering and the more sensitive it is to incoming light. However, a larger CCD chip of inferior quality may not necessarily be brighter than a smaller chip with a superior design. The 1/3" chip seems to be the most common size used in consumer security cameras. Consideration of CCD size is important when choosing the focal length as this will affect the coverage width and magnification.
While using cables is the most common way of transmitting surveillance video, wireless video is often used to deploy cameras in places where laying cable is problematic.
Many, if not, most security incidents happen outdoors. The challenge with outdoor surveillance is that this can be over large areas and those areas rarely have ready access to conduit, cables or existing network infrastructure. Wireless systems are used to overcome this problem.
Wireless systems range from simple $100 short tange kits to systems that cost tens of thousands and can cover cities. (Be careful with cheap wireless though as wireless system deployments are risky.) This video excerpt demonstrates the basic concepts behind wireless transmission.
If you are trying to learn the basics, the Video will help you see and appreciate the various aspects of video surveillance.
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