Rayco Security Loss Prevention Systems, Inc.
7737 Densmore Ave. • Van Nuys, CA, 91406
1 (818) 779-0900 tel • 1 (818) 779-0103 fax
E-Mail: info@raycosecurity.com

CCTV Information

Introduction

Designing CCTV security systems is quite simply a matter of putting together a number of components. You don't need a technical background or even a very comprehensive knowledge of how each of the components operate. But you do need to know what each component does and what its requirement is.

In this guide, we will describe most of the common closed circuit television components and supplementary equipment, and provide guidelines for their selection.

Basic CCTV Components

The three basic components of all CCTV security systems are the camera, the monitor, and the cable. While other supplemental components may be added into more complex systems, the camera, monitor and video cable form the core of all CCTV security systems.
A. The Camera
The camera is the eye of the system. Its only function is to provide a view of the site under surveillance by sending an electronic signal along a video cable. It is passive, it only views the scene similar to the human eye.
Tube cameras are no longer used for a few reasons. Tubes wear out, are fragile, more expensive, and cannot match the versatility of the CCD (Charged Coupled Device or 'chip') camera.
At Rayco Security, all of the cameras installed are CCD cameras. To date, not one camera has needed replacement due to worn out parts, degraded video output, or any other defect in the camera itself.
Our return service on a completed install is .5% to 1% annually. This is due to quality equipment, proper placement, and a well trained sales and technical staff.
B. The Monitor
The monitor receives the signal sent by the camera and converts the signal into a picture on a television screen. At least one monitor must be provided at each viewing station in the CCTV system in order to see the view provided by the camera(s).
C. The Cable
The cable required for a basic system is 75 ohm coax cable. RG59U is the normal coaxial cable used, this cable must be copper center conductor and 95% shield.

 
Each camera is connected by an individual cable to a switcher, and only one cable runs from the switcher to the monitor. This is because only one video signal can be transmitted on any monitor at any one time. The viewer uses the switcher to determine which camera's video signal will be sent onto the monitor and displayed on the screen. The viewer may make the selection manually or program a sequential switcher to automatically change from view to view.

In security CCTV systems with a large number of cameras, it is usually desirable to divide the cameras into groups and use a second switcher and a second monitor to provide views of the different areas.  

How To Select The Basic Components

A. Cameras

The first criteria for selecting a camera for a CCTV system is the minimum light level the camera must operate in. This criteria remains constant regardless of whether the camera is mounted indoors or outdoors.

CCD cameras can be divided into three classifications of operation based on lighting considerations. These three classifications are listed with descriptions of the levels of light.

General Purpose Cameras - Most general purpose cameras will work well indoors. Light levels must remain relatively high and evenly illuminated to effect a good quality picture. (With out the aid of auto-iris lenses or infrared illumination).

Low Lux Cameras - A low lux camera can in some instances 'see' with the illumination from a single lit match. In reality, CCD cameras see well in the infrared spectrum. A low lux camera is any camera with a lux(level of light measurement) below 1 lux. A lux of .5 is near total blackness to the human eye, yet to some CCD cameras it looks an overcast day. These low lux cameras are ALWAYS black and white output.

Color Cameras -Color cameras require an enormous amount of light compared to a black and white camera. A color camera would work well indoors with bright illumination. Outdoors, high intensity lights(75 to 150 watts) would be needed at night to reflect the colors back on to the camera. Daytime light usually is adequate for a color camera.

B. Monitors

Selection and placement of monitors is quite simple, but very important. The only decision is which size to use, and that is determined by the viewing distance. The table below provides a reference for determining appropriate monitor sizes:

Viewing Distance Recommended Monitor Size Recommended Monitor Size
14" - 36"
9" 
9" 
36" - 50"
12" 
12" 
50" - 76"
15" 
19" 

C. Switchers

There are four basic categories of switchers:

Manual Passive Switchers
Homing Sequential Switchers
Bridging Sequential Switchers
Alarm Programming Sequential Switchers

For your convenience, a simplified description of each of the four basic switcher types is described below:

Manual Passive Switchers

Manual passive switchers are the most economical way of connecting two or more cameras to a single monitor. The user changes from camera to camera by pushing a simple mechanical switch on the front of the switcher.

Homing Sequential Switchers

Homing sequential switchers can be set up to automatically switch from camera to camera. The amount of time each view stays on the monitor screen can be varied from 3 to 45 seconds. Once the cycling time has been established, any of the cameras can be either eliminated from the sequence or selected for extended viewing with the flip of a switch. Returning the switch to its normal position will include that camera in the program and start the cycle all over again. Homing sequential switchers can be homing, homing bridging, homing looping, and looping bridging.

Bridging Sequential Switchers

Bridging sequential switchers operate the same as the homing sequential switcher, but provide an outlet for one additional monitor. One is used to display any of the selected camera views while the second monitor provides the sequence of the cameras, allowing extended viewing of one special scene while continuing to display all scenes.

Alarm Programmed Sequential Switchers

Alarmed programmed sequential switchers perform like the above switcher but include one set of terminals for each camera position to call up that position by use of magnetic contacts, video motion detectors, or conventional motion detectors. Primarily used in conjunction with video cassette recording.

Camera-Related Equipment

For each camera in the system, there are four determinations to be made after you have selected the camera (by its operating light range and power supply).

The lens will determine the area viewed by the camera and help the camera adjust to varying light conditions.

Pan/tilts and scanners can provide greater coverage of an area with a single camera by moving the camera from side to side and up and down.

Housings protect the camera from environmental conditions and vandalism or conceal it from the public.

Mounts are required to place the camera in its intended location.

Lenses

How much of an area is "seen" and transmitted by a camera is determined by the focal length of the lens and whether or not it has a zoom function. Cameras operating in very low light conditions will may require auto iris and/or spot filtering to operate properly. Some newer CCD cameras have an electronic iris feature that allows a larger light range with out the use of auto-iris lenses.

Focal Length

The focal length of the lens determines the field-of-view of the camera. Short focal length lenses (low numbers) have a wide field of view and display more of the scene. Long focal length lenses (high numbers have a telephoto effect and provide more detailed views of distant targets.

NOTE: Increasing the monitor size does not increase the clarity of the image, it just enlarges the picture. If you need a good clear view of distant detail, you must use a lens selected for the specific application.

When selecting the field-of-view, a good rule of thumb is that 25% of the monitor height is a minimum for good identification of a person. The most direct way of determining the appropriate focal length (field-of-view) is to use a manual wide range zoom lens on a test camera at the intended site, as follows:

With the test camera in the selected location, run through the zoom range until the desired view is obtained. Then simply read the indicated focal length off the zoom lens.

The best means of calculating the required lens focal length without an actual test employs a lens selector guide supplied by several manufacturers.

Note 1:


As mentioned before, every CCTV system should be viewed with a test camera, test lens, and test monitor at the job site prior to a fixed price or firm quotation. Only if your customer can actually see the picture before he buys can you be sure they'll be entirely satisfied. A selection of lenses from the following chart or from your own graphs are approximations at most. The margin for error is high.

Fixed Focal Length Lenses Fixed focal length lenses have a permanent field-of-view. They are the most economical lenses available and are used in most general surveillance situations.

Angular Field-of-View (Approximate)

2/3" Format
Focal Length Horizontal Field of View
4.0 mm 95 degrees
4.5 mm 88 degrees
4.8 mm 85 degrees
6.0 mm 72 degrees
8.0 mm 57 degrees
9.0 mm 52 degrees
10 mm 47 degrees
16 mm 30 degrees
135 mm 14 degrees
1" Format on 2/3" Format
Focal Length Horizontal Field of View
5.5 mm 76 degrees
6.5 mm 68 degrees
8.0 mm 57 degrees
12.5 mm 38 degrees
25 mm 19 degrees
40 mm 16 degrees
50 mm 10 degrees
75 mm 6 degrees
135 mm 3 degrees

Zoom Lenses

Manual zoom lenses with the field of view variable by hand at the camera location.

Motorized zoom lenses with the field of view controlled by the viewer at the monitor (remote) location. Manual zoom lenses are rarely used in security application since camera access is generally impractical. Motorized zoom lenses are very effective for panoramic surveillance of an area with the capability of close inspection and identification of a person or object in the scene.

Iris control

The iris is a variable opening in the lens which can be closed down to limit the amount of light entering the camera. Most low light level cameras require lenses with automatic iris control . Auto-iris lenses are electronically controlled by the camera, but can be overridden with remote controls at the monitor location.

Spot Filter

A spot filter is an area in the center of the lens which greatly reduces the amount of light passing through it. When the iris is wide open, it has very little effect, but as the iris closes down, the spot filter occupies more and more of the open area and provides more filtration of light to the limits required by the tube. Spot filter lenses are only used with iris controls for low light level cameras.  

Voltage

The performance of 115VAC and 24VAC units is identical. The deciding factor is the cost of the power supply wiring. 115VAC units can use low gauge wire for very long distances, but conduit may be required by local ordinance or electrical code. 24VAC units require heavier gauge wiring, but conduit is not normally required.

Relay boxes allow the use of lighter gauge wire with 24VAC controls, 115VAC is required at or near the camera location.

See RCA/Panasonic data sheets for wiring requirements of individual units.

Auto-Scan

The auto-scan feature on pan & tilt units provides automatic horizontal sweeping of the camera to predetermined limits. The automatic control can be overridden to stop at any position or for manual control of the sweep. Use in the auto-pan mode is discouraged for outdoor applications and/or variable light conditions.

Accessories/Options

Variable speed in both pan and tilt functions
Explosion proof
Cable guards to reduce cable wear and prevent tangles
Preset position
 

Housings

If the camera location is indoors, a housing is usually required only to protect the camera from vandalism or to conceal it from view in a decorative globe unit . For outdoor installation, the addition of environmental accessories is required. The outdoor housing accessories are described below - the preceding reference chart is included showing available accessory features.

Accessories for Outdoor Housings

Heater: Protects down to -10 degrees Fahrenheit. Available in 115VAC & 24VAC models.

Extreme Low Temperature Package: Protects down to -80 degrees Fahrenheit.

Blower: Protects at temperatures above 90 degrees F. Available in 115VAC & 24VAC models.

Sunshield: Overall shade for high temperature protection.

Insulation: For both hot and cold environments.

Window Wiper: With and without washer to clean the window.

Controls: For all functions, can be operated from monitor area.
 

Mount Types

The unit mounting plate on each type of mount has a different bolt pattern to facilitate the unit. Cameras and housings can be mounted directly to pan & tilt or scanner units, which in turn require mounts for installation.

Weight Load - Add together the weights of all the units affixed to the mount.

Wall, Ceiling, Pedestal - Wall and ceiling mounts are recommended for indoor use, pedestal mounts for outdoor use. The clearance required by the mounted unit is the determining factor in selection.

Adjustable Heads - Adjustable heads are available on most mounts to provide vertical as well as horizontal adjustment of camera position.

Supplemental Components

Video Cassette Recorders - The addition of a video cassette recorder in CCTV systems adds a great deal of flexibility. It can be used to review the activities of the day or week, provide a visual record of all transactions, and provide unattended surveillance during non-business hours, although apprehension would not be a function of the system. A built-in time/date generator imprints the time and date on every scene for reference. For time lapse recording, the unit can be set to extend to two hour cassette tapes to up to 999 hours of surveillance by recording only at preset intervals. It can also be set up to respond to an intrusion by converting back to real time recording (no time lapse between recorded images), sounding an alarm and triggering any other alarm system or device.

Video Motion Detector

The video motion detector is a silent guard that can watch over a sensitive or vulnerable area in a building, such as a safe. When no employees are present, it maintains a constant vigil over the designated area, while rejecting certain types of false alarms. It can be integrated into a system to alert a video cassette recorder of an intrusion or initiate an alarm situation with other alarm devices. The primary detector requires a change in the video signal caused by light change. A constant stable lighted area is required.

Inserter/Splitter/Picture-in-Picture

This component splits the screen on a single monitor to accommodate pictures from two separate cameras simultaneously. This would work well if a store manager wishes to check on employees ringing up purchases on a cash register. By placing one camera with a narrow focal width on the cash register and a second camera with a wider focus on the counter, he is able to identify the merchandise and the price being rung up. If he doesn't have time to watch it during the day, he can include a video cassette recorder into the system and record the days' activity for review at a later date. Note: A splitter does not compress the whole picture into half the monitor - it only displays one-half the area being viewed. This device works best as a scene inserter as opposed to a splitter.

RF Modulator

Cameras send out their picture as a video signal (voltage). This signal can only be read by equipment designed to accept a video signal, such as monitors, switchers, and VCR's, etc. An RF modulator adapts the CCTV security camera signal for display on a standard home TV set. For example, in a condominium or apartment complex with a security gate or lobby, when someone comes to the gate and rings a tenant on an intercom, the tenant could view the visitor on his TV set on an unused channel assigned to the camera before answering the intercom.

Shared System

Any of the individual camera views may be viewed independently or included in the automatic program at either station. It also provides independent viewing at two separate locations.

Partially Shared System

Some of the camera views are available only to a single station. Some of the camera views are shared.

Bridging System

An automatic program on monitor 1 can be bridged onto a separate viewing station. Selected views may be held on monitor 1 without interrupting the automatic program on monitor 2.

How To Select The Video Switcher

Introduction

The broad range of video switching equipment currently available allows us to create closed circuit television systems to individualized needs with standard, off-the-shelf components. Unfortunately, the large variety of equipment has produced some accompanying confusion regarding its use.

Probably the most common misunderstood component in a CCTV system is the video switcher. This is particularly regrettable since the efficiency of the entire system is directly dependent on proper application of the correct switcher.

In an effort to provide a better understanding, we will examine here the basic switcher types and what functions they can provide in a CCTV system. Beginning with the most basic mechanical switcher and progressing through the sophisticated models, we will present each in a hypothetical system and consider how it will satisfy the requirements of an imaginary company.

We will start our company (and our system) very simple requirements. One of the executives (Mr. Smart) needs to occasionally view - without leaving his office - any or all of four nearby area: the front lobby, the production area, the shipping/receiving area, and the warehouse. Obviously, he will need four cameras, one for each location. And since he is the only one with viewing requirements, he will need only one monitor in his office. He will also need some means of selecting which video input will be displayed on his monitor at any given time. Mr. Smart needs a video switcher.
 

Choosing A Video Switcher

All switchers have a common basic function - they are used to determine which of the input signals will be taken off ground termination and applied to the output line - in this case, his monitor.

At present, Mr. Smart's budget is the most pressing concern, so we will provide him with the lowest price switcher available.

Manual Passive Switcher

A manual passive switcher will suit his modest requirements quote adequately. Like all switchers, it functions as a multiple-choice splice between input and outputs, in this case with the selection made manually. As the term "passive" suggests, this switcher contains no electronically active components. It merely allows Mr. Smart to select which of the available inputs he wants displayed on his monitor, and completes the appropriate circuit by mechanical means.

In using a passive switcher, Mr. Smart will have to put up with a few inconveniences. The force required to operate the mechanical switches will probably be just enough to require him to use his other hand to hold the desktop unit in place. Without benefit of internal electronics, switching to a new camera input will produce spikes, flashes, and a temporarily garbled image, which will take a second to clear. Occasional maintenance will be required to clean the mechanical switches.

If these minor annoyances are of no great concern to our Mr. Smart, he should be satisfied with a manual passive switcher

Manual Active Switcher

But suppose he isn't satisfied. Let's make our Mr. Smart a little more exacting. He can't afford the down time for maintenance. When he switches from the warehouse to shipping/receiving he wants to see a clear image immediately, and he's constantly on the phone so he needs feather-touch switching capability.

A manual active switcher should fill the bill. The electronic analog switch is activated by a feather-touch switch. internal circuitry, with vertical interval switching capability, provides instantaneous switching with no visual disturbances.

With a manual active switcher, Mr. Smart has eliminated the technical inconvenience of his previous passive switcher, but he still must make each video selection by hand. That may be all right for now, but let's increase his requirements and see what we can do for him. We'll assume he still has the same four areas to monitor, but now needs to check them more frequently.

Sequential Switcher

Now he needs someone or something to switch from camera to camera for him so that he can keep an eye on what's going on all over the plant with just an occasional glance at his single monitor.

A sequential switcher will do just that for him. Basically, an automatic active switcher can be programmed to progress from input to input, displaying each area in turn on the monitor in an indefinitely repeated cycle. Like the previous manual active switcher, it contains electronic circuitry to provide fast, clean switching, but it also provides the decided advantage of automatic switching. Of the wide variety of sequential switchers available, let's start our Mr. Smart out with the simplest and see what new capabilities it provides.

Homing Sequential Switcher

A homing sequential switcher will allow Mr. Smart to view each of the areas, one through four, in repeated sequence by simply turning the switcher on. He can vary the dwell time of each individual camera from 1 to 45 seconds. Thus, his programmed sequence could be camera one (of fleeting interest) for one second, camera two (more to see) for a full 30 seconds. In this configuration, the four (of moderate importance) will show for 15 seconds each. The switcher will automatically sequence through positions one through four, displaying each area for the allotted time and repeating the program every 61 seconds. Not all homing sequential switchers provide an adjustment for each input. Some provide one adjustment only, which means if the setting is 10 seconds that each camera scene will be displayed on the monitor for 10 seconds.

Once the standard program has been established, it can be extended over a sliding range up to twice the original dwell time settings. Thus, with a simple control knob, the sequencing can be slowed to up to 180 seconds, or double the individual dwell time settings.

Sometimes, however, the program requirements may call for the elimination of one of the cameras from the sequence. If Mr. Smart is overseeing the flow of materials from warehouse to production to shipping for a rush job, he probably doesn't care who is in the front lobby and may find it disturbing to have the view in his automatic sequence. If so, he can temporarily eliminate camera one from the program by simply moving the position switch on the unit to bypass. Thus, the sequence will now be two, three, four, two, three, four, etc., skipping number one until Mr. Smart decides he wants the lobby view back in the sequence and returns station 1 to automatic.

Suppose now a problem develops in the production area requiring Mr. Smart's full attention. By changing the switch for position two to select (or home), he can keep camera 2 input on the screen and temporarily override the sequential switcher like a manual switcher controlling which input is displayed by returning the previously selected switch to automatic (or bypass) and changing the appropriate switch to select.

Whenever he wishes, he can return to his standard sequencing program by simply returning all switch positions to automatic. The switcher will start all over again, progressing from one to two to three to four and back to one again, all to his original timing.

The homing sequential switcher provides Mr. Smart with a number of operational options, such as automatic switching, timing and bypass control, and individual hold of any of the available inputs. In the automatic switching mode, each of the four monitored areas will be displayed at preselected intervals, so he can keep abreast of what is happening all throughout the plant by merely glancing at the screen occasionally. If he sees something of concern to him, he can home in on it by putting the appropriate switch on select, thereby holding that single input on the screen in lieu of the programmed sequence.

Now, let's suppose Mr. Smart would like to have his cake and eat it too, so to speak. He wants to select individual views for extended study, but does not want to give up the constantly updated preview provided by the automatic sequence. We can give him that capability with a single switcher.

Bridging Sequential Switcher

A bridging sequential switcher is a sequential switcher with separate outputs for two monitors, one for the programmed sequence and the second for extended display of a single area. Unlike the homing sequential switcher the bridging sequential switcher provides this constant viewing of a selected input without giving up the overview of all areas provided by the sequential program.

With a bridging sequential switcher, when Mr. Smart wants to observe a particular area in detail changing that station to select will complete a circuit to monitor two, causing that input to remain in view indefinitely. Meanwhile, monitor one will continue uninterrupted with the original program sequence, including the view selected for independent viewing.

If Mr. Smart has security responsibility, he can record the selected image from monitor two output while keeping an eye on all the other areas for further developments.

VCR/Homing Sequential Switcher

On the topic of security, Mr. Smart has an important question: "Is there any way my system could be utilized when no one is there?" A welcome question, especially when we have two excellent answers.

One solution, of course, is to include a time lapse video cassette recorder in his system for use when the plant is unoccupied. For unattended surveillance, a time lapse VCR/homing sequential switcher system can be left on overnight or over the weekend. The switcher will continue through four, in sequence on the monitor, but the time lapse VCR will only record one out of every 6, 13, 25 or 38 frames, depending on which mode it is set in. Thus, when played back at normal speed, up to 72 hours of surveillance can be reviewed in 120 minutes of viewing (24 minutes at first playback).

But suppose even that's not enough for our Mr. Smart. What if he wants an extended look at any intrusion, recorded in real time? He needs a switcher that will respond directly to the intrusion itself, an auto alarming switcher.

Auto Alarm Sequential Switchers

Auto alarming sequential switchers come in either the one monitor homing format, or the two monitor bridging format. In either case, they can be triggered by a variety of sensing devices. Magnetic contacts, pressure sensitive floor mats, window foil stripping, motion sensors, and other intruder/detection devices can be connected directly to the switcher from any or all of the areas under camera surveillance.

First, let's equip our Mr. Smart with an auto alarming homing sequential switcher with the alarm turned on. The system will function exactly like the homing sequential switchers described above, until there is an intrusion.

In conclusion, Get Smart, Get Safe and Get RAYCO



Rayco Security Loss Prevention Systems, Inc.
7748 Gloria Avenue
Van Nuys, CA, USA, 91406
1 (818) 779-0900 tel
1 (818) 779-0103 fax
E-Mail: info@raycosecurity.com
copyright  Rayco Security Loss Prevention Systems, Inc.