Some of the most usable CCTV systems I have ever seen were put together by people who said over and over again, “I don’t know anything about this, but shouldn’t we ...” and then came up with a suggestion based on the specific application and common sense, not years of experience. Conversely, I have seen the same mistakes repeated over and over again by the “experts.”
We all live in the real world, but few of us actually work there. Think about that the next time you push a door that you should have pulled to open, try to unwrap the cellophane from a new CD, or fill out a form by writing above the line you should have written below. There is a poster in many engineering offices that depicts a bumblebee flying and has the slogan “Achieve the Impossible” - any engineer can prove to you that a bee can’t fly!
This article is divided into two sections. The first focuses on the elements of CCTV systems design that many of us don’t think of but annoy the people who use our systems day in and day out. The second section explores some of the high-tech features and buzzwords with an eye on the type of user benefits from each.
Understanding a CCTV User’s Frame of Mind
To understand where a design can go wrong, it is important to step back and look at the evolution of the CCTV, consumer electronics and entertainment industries. While they are not a combination we ordinarily put together, there are several interesting parallels that have brought us to where we are today.
The original CCTV systems were built using equipment intended for other uses, primarily broadcast or industrial television. Cameras were large, expensive, power-hungry and required frequent maintenance. Tubes had to be changed every 12 months to 18 months, and the heat those units generated allowed this fledgling industry to look upon service calls as a continuing and lucrative revenue stream.
Meanwhile, in the consumer electronics market, video rentals and the amateur videographer were coming on the scene. VCRs changed from a pricey luxury to a necessity, and inexpensive CCD cameras were married to lightweight portable VCRs to create the camcorder.
From this melting pot steps forth today’s CCTV user. He or she is not intimidated by buttons and will happily press them all day long. Crisp, clear video images are taken for granted as are time-shifting and reviewing video recordings. The available choices in equipment increase daily as the prices continue to drop. And, if that isn’t enough of a challenge, the blinking clock on the front of people’s home VCRs is a testament to their unwillingness to read manuals.
Much as the consumer audio industry made everyone believe they were an audio engineer, the video boom has created a generation of people with very specific expectations of their video systems and a penchant for instant gratification.
No Matter the Type, Each Job Needs a Plan
In looking at our users and the events that conspired to create them, we must recognize the tremendous variety of situations in which they can be found.
I divide a system into three functional areas, regardless of size: system viewing and control, device selection and placement, and event documentation. They are equally important to each application and, to complicate the issue, all of them must be addressed simultaneously.
System Viewing and Control Is Goal No. 1
The most critical information needed for designing a system is not what will be covered, how many cameras, or any of the other obvious questions. It is simply, “How will the system be used?”
The selection of devices, number of monitors and recording methods are all dependent on the intended use of the equipment.
I always try to see if the system will be used for surveillance or security. While these terms are often used interchangeably, I define them as follows: security watches things while surveillance watches people.
To determine the intended use, ask some pointed questions. How will the system be used? Will operators be specially trained? Will the console be manned at all times? How important is the unattended recording of certain cameras?
Once the intended purpose has been determined, the environment may be designed to handle that functionality. But first, let’s take a closer look at security vs. surveillance.
Security: Capturing Images on Tape
Security systems often rely on unattended recording. Since an operator may be called away at any given moment, the ability to go back and see the “tale of the tape” is critical.
Systems that are left unattended are strictly security systems. They are also characterized by more fixed than movable cameras and frequently rely on many monitors, with the intent that an operator may see something out of the corner of his or her eye.
A security system will have more automation than a surveillance system. Integration with other systems, such as access control and intercom, is more prevalent here.
Surveillance: Observing and Taping for Backup
Users of surveillance systems are as concerned with how something happened as they are with what happened. They generally are looking for deviations from established procedures. When they see them, they watch further to see what is going on behind the scenes.
In this scenario, fewer monitors are used and screen size is generally larger. Pan-tilt devices are more prevalent - with the overwhelming choice being the discreet dome - to prevent a subject from knowing that they are being watched.
Needs Drive Device Selection, Placement
Moving into the second of the three main system design categories makes their interaction more apparent. With the selection of devices, we also must consider the way they will be viewed, controlled and recorded.
Many units will acquire targets rapidly but all are limited to only being one place at a time. Fixed vs. moving is one of the first decisions to be made and will vary from camera to camera, room to room and job to job.
With cameras, color vs. black and white is an easier decision. Monochrome cameras still offer better low-light response and a sharper picture, dollar for dollar.
Many applications will not permit color; sodium vapor lights commonly used in parking lots and garages cast an orange hue that will render any color information useless. Rooms with two strong light sources - sunlight through a window and bright fluorescent lighting - will not allow a color camera to accurately white-balance.
Color, on the other hand, aids tremendously in identification of people and objects. Sometimes these added visual cues can be more hindrance than help.
Intended Use Decides Event Documentation
As with device selection, the manner in which a CCTV system will be operated determines the method to be used. Also, when the decision is made to record an event, careful consideration must be given as to how.
Since it affects so many parts of the purchase decision, our first step is to evaluate analog vs. digital technologies. The future is clearly digital, but no one can say for sure how long the “transition period” we are currently in will last.
Multiplexing Departs From 1:1 Recording
When we depart from 1:1 recording, we have two alternatives: screen-division (or “quads”) and time-division multiplexing.
In screen-division multiplexing, a quad divides the screen into four quarters (or quadrants) and places a separate, full-motion picture in each.
A time-division multiplexer is another alternative that distributes multiple cameras into the full-motion video stream of 30 frames per second (fps), placing one camera in each frame.
Digital Eliminates Analog’s Limitations
After looking at the various analog technologies available, digital recording starts to look like the proverbial Ginsu knife advertised on late-night TV.