that uses video motion detection techniques to improve

the camera update times. It can also give a relay closure.

ANGLE OF VIEW - The angular range that can be focused

within the image size. Small focal lengths give a wide

angle of view, and large focal lengths give a narrow field

of view.

APERTURE - The opening of a lens which controls the

amount of light reaching the surface of the pickup device.

The size of the aperture is controlled by the iris adjustment.

ALARMING - The ability of CCTV equipment to respond to

an input signal, normally a simple contact closure. The

response varies depending on equipment type.

ASPECT RATIO - The ratio of the picture frame width to

the picture frame height in standard TV systems. It is 4

units

horizontal over 3 units vertical.

ASPHERICAL LENS - A lens designed with a non spherical

shape so that it refracts the light passing through it to

either lower the lens aperture so that it passes more light

or decrease barrel distortion on wide angle lenses.

AUTOMATIC FREQUENCY CONTROL (AFC) - An electronic

circuit used whereby the frequency of an oscillator is

automatically maintained within specified limits.

AUTOMATIC GAIN CONTROL (AGC) - An electronic circuit

used by which the gain of a signal is automatically adjusted

as a function of its input or other specified parameter.

AUTOMATIC IRIS LENS - A lens in which the aperture

automatically opens or closes to maintain proper light levels

on the faceplate of the camera pickup device.

AUTOMATIC LEVEL CONTROL (A.L.C.) - A feature on Auto

lris lenses (also known as the peak/average control).

Adjusting this control allows the auto iris circuitry to

either take bright spots more into consideration (peak),

bringing out detail in bright areas, or less into consideration

(average) bringing out detail in shadows.

AUTO-TERMINATING - A feature where the equipment

(ex. Monitor) automatically selects the correct termination

depending on whether the video output BNC is connected.

AUTO WHITE BALANCE - A feature on color camera that

constantly monitors the light and adjusts its colour to

maintain white areas.

ATTENUATION - A decrease or loss in a signal.

BACK FOCAL DISTANCE - The distance from the rear most

portion of the lens to the image plane.

BLACK LEVEL - The level of the video signal that corresponds

to the maximum limits of the black areas of the

picture.

BACK LIGHT COMPENSATION(B.L.C.) - A feature on newer

CCD cameras which electronically compensates for high

background lighting to give detail which would normally

be

silhouetted.

BLANKING - The process of cutting off the electron beam

in a camera pickup device or picture tube during the

retrace period.

It is a signal that is composed of recurrent pulses at line

and field frequencies. It is intended primarily to make the

retrace on a pickup device or picture tube invisible.

BLOOMING - The halation and defocusing effect that

occurs around the bright areas of the picture (highlight)

whenever there is an increase in the brightness intensity.

is paralleled, usually through a switch, to a source of video.

“C” MOUNT/”CS” MOUNT - CCTV lenses are available in two

different lens mounts. “C-mount” lenses have a flange back

distance of 17.5mm vs. 12.5mm for “CS-mount” lenses.

Many of today’s cameras can accept either type of lens, but it

is important to make sure that camera and lens are compatible

and set up properly. C-mount lenses can be used on CS-mount

cameras by utilizing a 5mm adapter or adjusting the camera for

C-mount lenses. Because of the shorter back focal distance,

CS-mount lenses can only be used on CS-mount cameras.

Your picture will be out of focus if you use a CS-mount lens on

a C-mount camera.

C.C.D. (CHARGED COUPLED DEVICE) - A C.C.D. chip that is

the pick up devise on a camera, performing a simular function

as a camera tube.

CONDITIONAL REFRESH - A technique used in slow and fast

scan transmission equipment, where only small screen changes

are transmitted. Up to a certain percentage of the on-screen

picture can be updated before a full picture is required.

CANDLEPOWER - The unit measure of an incident light.

CCTV - The common abbreviation for Closed Circuit Television.

COATINGS - Light is lost by reflection from optical surfaces

that are intended to be refractors only. This loss is effectively

reduced by very thin coatings on the lens surfaces. This can be

seen as a blue or violet hue on the lens surface.

COAXIAL CABLE - A type of cable capable of passing a range

of frequencies with low loss. It consists of a hollow metallic

shield in which one or more center conductors are put in place

and isolated from one another and from the shield.

COLOR BURST - The portion of a composite video signal that

comprises a few cycles of a sine wave of chrominance

subcarrier frequency used to establish a reference for

demodulating the chrominance signal.

COMPOSITE VIDEO - The combined video signal that includes

the picture signal, the vertical and horizontal blanking and

synchronizing pulses.

CROSSTALK - An undesired signal that interferes with the

desired signal.

DB (DECIBEL) - A measure of the power ratio of two signals.

It is equal to ten times the logarithm of the ratio of the two signals.

DC TYPE LENS - An auto-iris lens with internal circuit which

receives voltage and a video signal from the camera to adjust

the iris.

DEPTH OF FIELD - The front to back zone in a field of view

which is in focus in the televised scene. With a greater depth

of field, more of the scene, near to far, is in focus. Increasing

the f-stop number increases the depth of field of the lens.

Therefore, the lens aperture should be set at the highest f-stop

number usable with the available lighting. The better the lighting,

the greater the depth of field possible. In other words, the

depth of field is the area in front of the camera which remains in

focus. The larger the f-number the greater is the depth of field.

DIGITAL - A signal that levels are represented by binary numbers.

DISTRIBUTION AMPLIFIER - A device that accepts a (video)

signal and sends it out to a number of independent outputs.

DUPLEX (MULTIPLEXER) - A multiplexer that allows the user

to look at multi-screen imagess while performing time multiplex

recording.

DWELL TIME - The length of time a switcher holds on a

camera before moving on to the next in sequence.

E.I. (ELECTRONIC IRIS) - Automatically changes a CCD

camera’s shutter to mimic Auto Iris control, allowing fixed or

manual iris lenses to be used in a range of areas that used to

require an auto iris lens.

US TV standard 525 lines 60 fields.

ELECTRONIC SHUTTERING - Electronic shuttering is the

ability of the camera to compensate for moderate light changes

in indoor applications without the use of auto iris lenses.

EQUALIZATION - The process of correcting losses of certain

components in a signal.

EXTENSION TUBE - Kit consisting of various size spacers that

are used between the lens and the camera to reduce the lens

M.O.D. Generally used for very close-up applications.

Not recommended for zoom lenses due to loss of tracking.

F-NUMBER - The f-number indicates the brightness of the

image formed by the lens, controlled by the iris.

A smaller f-number means a brighter image.

F-STOP - A term used to indicate the speed of a lens.

The smaller the f-number, the greater is the amount of light

passing through the lens.

FIBER OPTICS - Flexible glass fibers used to conduct energy.

It is valuable in the coupling of multi-stage image intensifiers.

FIELD - One half of a frame, consisting of either the odd or the

even numbered lines, 60 fields are transmitted every second.

FLANGE BACK - The distance from the flange of the lens

(beginning of the lens mount) to the focal plane. C-mount

lenses have a flange back distance of 17.526mm vs. 12.5mm

for CS-mount.

FOCAL LENGTH - The distance from the center of the lens to

a plane at which point a sharp image of an object viewed at an

infinite distance from the camera is produced. The focal length

determines the size of the image and the angle of the field of

view seen by the camera through the lens. That is the distance

from the center of the lens to the pickup device.

FOOTCANDLE - It is the light intensity (illumination) of a

surface one foot distant from a source of one candela.

It is equal to one lumen per square foot. (1FC = 1 lm ft2).

The footcandle is the unit used to measure incident light.

FRAME - The total area of the picture which is scanned while

the picture signal is not blanked.

FRONT PORCH - The portion of the composite video signal

which lies between the leading edge of the horizontal blanking

pulse and the leading edge of the corresponding synchronizing

pulse.

GEN-LOCK - A method used to synchronize one or more

cameras by external means such as: composite video,

composite sync, horizontal or vertical sync.

GHOST - A shadowy or weak image in the received picture,

offset either to the right or to the left of the primary image.

It is the result of transmission conditions where secondary

signals are created and received earlier or later than the primary

signal.

GROUND - An electrical connection point that is common to

either a metal chassis, a terminal, or a ground bus.

GROUND LOOP - Caused by different earth potentials in a

system. Effects video pictures in the form of a black shadow bar

across the screen or as a tearing in the top corner of a picture.

HI-Z (UNTERMINATED) - Video input of a piece of CCTV

equipment, wired so as to allow the video signal to be fed to

further equipment. Does not necessarily include extra sockets

for the extra coaxial cables.

HORIZONTAL BLANKING - The blanking signal that is

produced at the end of each scanning line.

HORIZONTAL (HUM) BARS - Horizontal bars, alternately black

and white, which extend over the entire picture. They are known

as venetian-blinds. They may be stationary or move up or

down. They are often caused by approximately 60 Hertz

interfering frequency or its harmonic frequencies.

HORIZONTAL RESOLUTION - The maximum number of

individual picture elements that can be distinguished in a single

scanning line.

IMAGE SIZE - Reference to the size of an image formed by the

lens onto the camera pickup device. The current standards are:

IMPEDANCE - The opposition which a circuit or component

offers to the flow of electric current. It is expressed in ohms and

is equal to the ratio of the effective value of the voltage applied

to the circuit to the resulting current flow. In A.C. circuits, the

impedance is a complex quantity that includes both resistance

and reactance. In D.C. circuits, it is purely resistive.

INCIDENT LIGHT - The light that is falling directly over an object.

INSERTION LOSS - The signal strength loss that occurs when

a piece of equipment is inserted into a line.

INTERLACE - A scanning process where every other horizontal

line is scanned in one field while the alternate lines are scanned

in the next field to produce a complete picture frame.

INTERLEAVING - A method used in alarms or activity detection

which allows extra frames of video from alarmed cameras to be

added to a time multiplexed sequence whilst a state of alarm

exists.

Digital phone lines that allow transmission of video signals via

fastscan at speeds of 128Kb/second; used with terminal

adapters.

LAG - The image retention of an object after the object has

been scanned. Sometimes, it causes smearing effect.

LEVEL CONTROL - Main iris control. Used to set the auto-iris

circuit to a video level desired by the user. After set-up, the

circuit will adjust the iris to maintain this video level in changing

lighting conditions. Turning the control towards High will open

the iris, towards Low will close the iris.

LINE LOCK - To synchronize the field sync pulses, of an AC

powered camera, to the frequency of the voltage input

(line voltage).

LOOPING - A term indicating that a high impedance device has

been permanently connected in a parallel to a video source.

LUX - A unit of measuring the intensity of light. (1 FC = 10 lux).

MANUAL IRIS LENS - A lens with a manual adjustment to set

the iris opening (F stop) in a fixed position. Generally used for

fixed lighting applications.

MATRIX SWITCHER - A switcher able to route any of its

(camera) inputs to any of its (monitor) outputs, they often

include telemetry control.

MECHANICAL FOCUS (BACK-FOCUS) - The mechanical

aligning of the imaging device with the focal point of the lens;

it is most important on zoom lenses to be sure the image stays

in focus throughout the zoom range.

MINIMUM OBJECT DISTANCE (M.O.D.) - The closest

distance a given lens will be able to focus upon an object.

This is measured from the vertex (front) of the lens to the

object. Wide angle lenses generally have a smaller M.O.D. than

large focal length lenses.

MODULATE - To change or vary some parameter such as

varying the amplitude of a signal for amplitude modulation or

the frequency of a signal for frequency modulation. The circuit

which modulates the signal is called a modulator.

MONOCHROME - Having only one color. In television it is

black and white.

MONOCHROME SIGNAL - In monochrome television, a signal

for controlling the brightness values in the picture. In color

television, the signal which control the brightness of the picture,

whether the picture is displayed in color or in monochrome.

N/D (NEUTRAL DENSITY) FILTER - A filter that attenuates

light equally over the whole visible spectrum.

NOISE - Random spurts of electrical energy or interference.

NTSC - National Television Systems Committee that worked

with the FCC in formulating the standards for the United States

color television system.

PASSIVE - A non powered element of a system.

PEAK-TO-PEAK - The amplitude difference between the most

positive and the most negative excursions of a signal.

PINHOLE LENS - Lens used for applications where the

camera/lens must be hidden. Front of lens has a small opening

to allow the lens to view an entire room through a small hole in

a wall.

POWER - The rate at which electrical energy is applied to or

taken from a device. It is expressed in terms of watts, milliwatts

or microwatts.

PRE-POSITION LENSES - Zoom lenses which utilize a

variable-resistor (potentiometer) to indicate zoom/focus

position to the lens controller. After initial set-up, this allows the

operator to view different pre-set areas quickly without having

to re-adjust the zoom and focus each time.

RANDOM INTERLACE - A scanning technique commonly used

in CCTV systems in which there is no external control over the

scanning process. That is, there is no fixed relationship

between adjacent lines and successive fields.

RANGE FINDER - Used to determine the focal length needed

and what the picture will look like on the monitor. The user

looks through the device and adjusts the range finder to the

desired picture. Numbers on the outside of the range finder

indicate the focal length needed.

RASTER - The rectangular pattern of scanning lines upon

which the picture is produced. The illuminated face of the TV

monitor without the video information present.

REFLECTED LIGHT - The scene brightness or the light being

reflected from a scene. Usually it represents 5 to 95 percent of

the incident light, and it is expressed in foot-lamberts.

RESOLUTION - A measure of the ability of a camera or television

system to reproduce detail. That is the number of picture

elements that can be reproduced with good definition. It is a

factor of the pickup device or the TV CRT characteristics and

the video signal bandwidth.

RETAINED IMAGE (IMAGE BURN) - A change produced in or

on the target of the pickup device which remains for a large

number of frames after the removal of a previously stationary

light image and which yields a spurious electrical signal that

corresponds to that light image.

RADIO FREQUENCY (R.F.) - Signals with a repetition rate

above audible range, but below the frequencies associated with

heat and light.

ROLL - A loss of vertical sync which causes the picture

to move up or down on the TV screen.

RS232 - A commonly used computer serial interface.

SATURATION (COLOR) - The vividness of a color. It is directly

related to the amplitude of the chrominance signal.

SCANNING - The rapid movement of the election beam in a

pickup device of a camera or in the CRT of a television receiver.

It is formatted in a line-for-line manner across the photo sensitive

surface which produces or reproduces the video picture.

When referred to a video surveillance field, it is the panning or

the horizontal camera motion.

SENSITIVITY (PICKUP DEVICE) - The amount of current

developed per unit of incident light. It can be measured in

watts with the projection of an unfiltered incandescent source

of light at 2870 K degrees to the pickup device surface area.

It can be then expressed in footcandles.

SIGNAL TO NOISE RATIO - The ratio between a useful video

signal and unwanted noise.

SIMPLEX (MULTIPLEXER) - A multiplexer that allows the user

to look at multi-screen imagess or perform time multiplex

recording. It cannot record multiplexer pictures while showing

multi-screen pictures.

SPOT FILTER - A small insert used in a lens to increase the

f-stop range of the lens.

S/N (SIGNAL TO NOISE) RATIO - Measure of noise levels of a

video signal: the higher the number the better.

SUPER.V.H.S. (SUPER VIDEO HOME SYSTEM) - A new

format of high resolution VHS video recorders, capable of giving

greatly improved picture if all features and special tapes are used.

VHS compatible.

SYNC - Electronic pulses that are inserted in the video signal

for the purpose of assembling the picture information in the

correct position.

TEARING - A picture condition in which horizontal lines are

displaced in an irregular manner.

TELEMETRY - A system utilizing “control code” ‘transmitters

and receivers - They can use either video cable or a simple

twisted pair cable to send their information.

TERMINATION - A non-inductive resistor that has the same

resistance as the characteristic of the cable being used.

TIMEBASE CORRECTOR (T.B.C.) - An electronic circuit that

aligns unsynchronized video signals before signal processing.

Used in multiplexers and quad splatters.

TRACKING - A zoom lens’ ability to remain in focus during the

entire zoom range from wide angle to telephoto position.

VERTICAL INTERVAL - The time of vertical retrace.

VERTICAL RETRACE - The return of the electron beam to the

top of a television picture tube screen or a camera pickup

device target at the completion of the field scan.

VIDEO MOTION DETECTION - A system that uses the video

signal from a camera to determine if there is any movement in

the picture and set of an alarm.

VIDEO TYPE LENS - An auto-iris lens without an internal

circuit to control the iris. All iris control voltages come from a

circuit located within the camera.

VIDICON - A common type of camera pickup tube.

It translates the effect of light striking its photo-sensitive

surface into electrical impulses.

ZOOM LENS - A lens system that may be effectively used as

a wide angle, standard or telephoto lens by varying the focal

length of the lens.

ZOOM RATIO - The ratio of the starting focal length

(wide position) to the ending focal length (telephoto position)

of a zoom lens. A lens with a 10X zoom ratio will magnify the

image at the wide angle end by 10 times.