AMA
Security
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CCTV
Dictionary
Activity Detection: A feature of the video
multiplexer range that uses video motion detection techniques to improve the
camera update times.
Alarming: The ability of CCTV
equipment to respond to an input signal, normally a simple contact closure. The
response varies depending on equipment type. Many cameras have alarming
functions built-in; however, most CCTV installations today use the DVR as a
central monitoring of motion and alarm responses.
A.L.C. (Automatic Level
Control): On
AI 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
Analog: A signal in which any level
is represented by a directly proportional voltage; not digital.
Angle of view: The angular range that can
be focused with a given lens. Small focal lengths give a wide angle of view,
and large focal lengths give a narrow field of view. A 3.0 mm lens and lower is considered a wide
angle lens.
Aperture: The opening of a camera lens that controls the amount of light
reaching the surface of the pickup device (CCD). The size of the aperture is
controlled by the iris adjustment. By increasing the f stop number (f1.4, f1.8,
f2.8, etc.) less light is permitted to pass to the pickup device.
Aspect ratio: The ratio of the picture frame width to the picture frame
height in standard broadcast TV systems. It is typically 4 units horizontal
over 3 units vertical or a 4:3 ratio.
Aspherical Lens: A lens with a non-spherical shape refracts the light
passing through it. It is typically used
on wide angle lenses to decrease distortion or fisheye effect or it is used to
allow more light to pass by lowering the lens aperture
Attenuation: A decrease or loss in a signal. The longer a cable extends, the more
attenuation, or weaker signal occurs.
Automatic Frequency Control (AFC): An
electronic circuit used whereby the frequency of an oscillator is automatically
maintained within specified limits.
Automatic gain control (AGC): A feature that is used to automatically
adjust the signal strength based on certain parameters based on the signal
input and other specified parameter.
Found on many DVRs.
Auto Iris lens: A lens in which the aperture automatically opens or
closes to maintain proper light levels on the camera pickup device (CCD). This function allows the lens to
automatically adjust to lighting conditions.
Used in all outdoor cameras and many indoor with outside reflecting
light or changing ambient light levels.
Automatic Level Control (A.L.C.): A feature on Auto iris lenses (also
known as the peak/average control). This allows the Auto Iris lens to either
take bright spots more into consideration (peak), that allows detail in bright
areas, or less into consideration (average) bringing out detail of shadows or
darker areas of the picture view.
Auto-Terminating: Feature whereby the
equipment automatically selects the correct termination depending on whether
the video output BNC is connected.
Auto White Balance: A feature on many color cameras that monitors the
light and adjusts its color to maintain the light areas.
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BNC: British Naval
Connector. A trivia question
somewhere. The traditional CCTV camera
termination method. BNC connectors come
in twist-on or crimped connections.
Back focal distance: There is a mechanical back focal distance -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. Optical
back focal distance is the distance from the rear most portion
of the lens glass to the image plane. .
Back Light Compensation (B.L.C.): A feature on professional CCTV cameras
which electronically compensates for high background lighting to give detail
which would normally be silhouetted. It allows
adjustment to compensate for shadows and dark areas in the camera view.
Bandwidth: A measure of the load and capacity of information over a
network. Video transmission takes more bandwidth to transmit over a network
than text.
Black level: The video signal level that corresponds to the maximum
limits of the black areas of the picture.
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"C"
mount/"CS" mount: CCTV lenses come in two different lens mounts. The
"C-mount" lenses have a flange back distance of 17.5mm vs. 12.5mm for
"CS-mount" lenses. 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. CS-mount lens cannot be used on a C-mount camera. Most CCTV cameras
accept either C or CS-mount lenses.
CCD. (Charged Coupled Device): A CCD is an electronic chip that is the
receiving device on a camera. Sony CCDs
are the most popular and largest share of CCD market
CCTV: The common abbreviation for Closed Circuit Television. The common term for a “closed” video system
or one that is used for the specific purpose as to not broadcast and is
typically used for video security and surveillance.
Candlepower: The unit measure of a light intensity.
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. Common conductor material is
copper and aluminum is used in cheaper coax cable. Siamese coax is coax cable with a pair of
wires for camera power.
Composite video The combined video signal that includes the picture
signal, the vertical and horizontal blanking and synchronizing pulses. It is a simple two-wire connection that is
commonly used in video monitors and monitor output on DVRs.
Crosstalk: An undesired signal or noise that interferes with the signal.
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Database: A collection of data used and
produced by a computer program.
db (Decibel): A measure of the power ratio of two signals. A unit used
to express relative difference in power or intensity, usually between two
acoustic or electric signals, equal to ten times the common logarithm of the
ratio of the two levels.
DC TYPE lens: An auto-iris lens with internal circuitry that receives
the video signal from the camera to adjust the iris. Common Auto-Iris lens
Default Gateway The IP Address of the Router that is used to send
information from one network to another.
Depth of field: The front to back zone in a field of view which is in
focus in the picture 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. 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. 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 Recording: This is the latest form of
recording and is relatively new to the CCTV industry as a result is not the
most economical method however it does have several advantages over the VCR
analogue tape recorders. First of all it enables quick access to the desired
Duplex (multiplexer): A multiplexer that allows the user to look at
multi-screen images while performing time multiplex recording.
Dwell Time: The length of time a monitor or DVR maintains a view on a
given camera before moving on to the next view.
Many DVRs will rotate between views based on alarms and the dwell time
allows a specified time to view each screen before it is refreshed
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E.I.
(Electronic Iris):
Automatically changes a CCD camera¹s 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. Not as
efficient as Auto-Iris lenses and cameras
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.
Ethernet: A type of LAN connection and protocol that is recognized as an
industry standard. Used on most all IP networks
F
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f-number: The f-number indicates the brightness of the image
formed by the lens, controlled by the iris. A smaller f-number allows a
brighter image.
f-stop: A term used to indicate the speed of a lens. The smaller the f-number,
the larger the amount of light passing through the lens.
Facial Capture: In order to obtain
facial capture surveillance for positive identification purposes, cameras
should be mounted at vertical height conducive for facial capture (for example,
in light switches). Lenses selected should produce identification level imaging
and no less than 120% vertical image of the person.
Field: 60 fields are transmitted every second and one
half of a frame, consisting of either the odd or the even numbered lines..
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 focal length determines the size of the image and the
angle of the field of view seen by the camera through the lens. The focal
length is 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. That is the distance from the center of the lens to the pickup
device.
Foot-candle: 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 foot-candle 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.
Full Duplex: The simultaneous data transmission in both directions of a
signal path
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Gen-lock A method used to synchronize one or more cameras
by external means such as: composite video, composite sync, horizontal or
vertical sync. Old stuff…
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. Weak video
signals from the camera.
Ground: An electrical connection point that is common to a metal
chassis, a terminal, or a ground bus that is grounded
Ground Loop: Caused by different earth potentials in a system. In other
words, one of them or both are not grounded properly. It sometimes affects video pictures in the form
of a black shadow bar across the screen or as poor video at top corner of a
picture.
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Horizontal blanking: The blanking signal that
is provided at the end of each scanning line of the video signal
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 poor wiring and
AC power (60 Hertz) interfering with the video signal.
Horizontal resolution: The maximum number of individual picture elements
that can be distinguished in a single scanning line.
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I.R. (Infrared): A range of frequencies
lower than visible red light used for covert surveillance or as a low cost
wireless video link. An Infrared can
view at “No-Light” conditions by illuminating the IR LEDs that surround the camera
lens.
IP
Address (Static and DHCP): Identifies a particular computer on a network to other
computers. An IP address is similar to your home address. In a neighborhood,
each house has a unique address; on a network each computer must have a unique
address. There are two types of IP Addresses - static and DHCP. A Static
address is where someone physically connects to a computer and defines the
IP address for that computer. A static address does not change unless someone
physically changes it. DHCP or a Dynamic address is
dynamically assigned from a server that contains a pool of addresses. The
server leases the computer one of the available addresses for a specified
amount of time. Once the specified time has expired, the computer renews the
lease or requests a new IP address.
Image size: Reference to the size of an image formed by the lens onto
the camera pickup device. The current standards are: 1", 2/3",
1/2" and 1/3" measured diagonally.
1/3” is most common
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 ambient light that is directly over an object.
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.
Internet: A public network of computers and people sharing information.
Anyone can access the Internet through an Internet service provider. I heard this may get popular!
Intranet A private network of computers using that allows a group within
a company to share information across their group network and not outside the
internal network.
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Lag: The image retention of an
object after the object has been scanned. Sometimes, it causes a smearing
effect.
LAN: Local Area Network; multiple computers connected together to share
information. Shared information could be e-mail, files, and printers.
Line Lock: In an AC-powered camera, it synchronizes the field sync
pulses, to the frequency of the voltage input (line voltage).
Lux: A unit of measuring the intensity of light. (1 FC = 10 Lux). A
common measurement of a CCTV camera’s ability to view in low-light conditions.
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Manual
iris lens:
A lens with a manual adjustment to set the iris opening (F stop). Generally used
for indoor or fixed lighting applications.
Matrix Switcher: A switching device that routes camera inputs to any
monitor outputs for viewing
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 (MOD): 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 MOD than large
focal length lenses.
Monochrome: Having only one color. In CCTV and television it is black
and white.
Motion
Detection:
A feature that uses the video signal from a camera to determine movement (pixel
changes) and react by recording the video or setting an alarm condition
MPEG: MPEG
is a video compression method commonly used in digital recording. MPEG-1 is a
standard for CD-ROM video and audio. MPEG-2 is a standard for full-screen,
broadcast quality video.MPEG-4 is a standard for video telephony.
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Network: Computers connected together to share information. Think of a
network as a city and the computers as houses within the city. Two types of
networks are LAN and WAN.
Noise: Random electronic noise signals that are not part of the primary
signal. Electrical energy or
interference.
NTSC: NTSC (National Television System Committee) is an organization
that formulated the standards for the current
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Passive: A non powered element of a
system. Baluns are an example of a
passive device.
PAL: PAL (Phase Alternation Line) is a European color TV system
featuring 625 lines per frame, 25 frames per second and 50 fields per second.
PAL is used mainly in Europe,
Pinhole lens: Lens used for security 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 or device.
Pixel: Short for picture element, Pixels are the tiny dots of
information that make up a digital image. The more pixels there are on the
camera's image sensor (CCD or CMOS), the higher the image resolution will be.
The higher the resolution, the clearer an enlarged print can be.
Power: The rate at which electrical energy is applied to or taken from a
device. Power is expressed in terms of watts.
Pre-position lenses: Allows the operator to view different pre-set areas
quickly without having to re-adjust the zoom and focus each time.
Quad: A CCTV device that
switches up to four (Quad) video signals and simultaneously displays the images
onto one monitor.
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Raster: The rectangular pattern of scanning lines upon which the picture
is produced. The illuminated portion of the video monitor.
Resolution. That is the number of picture elements (pixels) that can be
reproduced on the video or picture. It is a factor of the pickup device or the
monitor characteristics and the video signal bandwidth. It is the measure of
the ability of a camera or television system to reproduce detail and the higher
the resolution the higher the quality of the video.
Roll: A loss of vertical sync which causes the picture to move up or
down on the TV screen.
Router A router is a device that connects two networks. The router reads
the destination address of information sent over a network and then sends the
information to the next route point A
traffic cop.
RS232: A commonly used computer serial interface.
RS485: A commonly used CCTV serial interface for PTZ
control and for POS interfaces
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Sensitivity: The amount of current
developed per unit of incident light. How sensitive to light is a CCD
Camera. It can be measured in watts with
the reference of an unfiltered incandescent source of light at 2870 K degrees
to the pickup device surface area. It can be then expressed in foot-candles.
Server: A computer and its software that provides some service for other
computers connected to it through a network.
Signal to noise ratio: The ratio between the video signal and unwanted
electrical noise.
Simplex (multiplexer): A multiplexer that allows the user to look at
multi-screen images or perform time multiplex recording.
Spot Monitor: A feature on DVRs that allows a secondary
monitor (s) to monitor certain video channels.
S/N (Signal to noise) Ratio: Measure of noise levels of a video signal:
the higher the number the better.
Sync: Electronic pulses that are inserted in the video signal for the
purpose of maintaining the picture information in the correct position.
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Termination: A non-inductive resistor
that has the same resistance as the characteristic of the cable being used.
Tracking: A zoom lens' ability to remain in focus during the entire zoom
range from wide angle to telephoto position. Also a CCTV feature that allows a
camera to track an object by focusing in on an object that is sensed by motion
detection.
T.V.L. (Television Lines - Resolution): The maximum number of changes between light and dark on a
picture across 3/4 of the width dictates the resolution of a CCTV product,
measured in TVL. Broadcast video is 540
TVL. CCTV high resolution is currently
considered 480 TVL and above.
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Vertical retrace: The return of the electron beam to the top
of a television picture tube screen or a camera pickup device (CCD) target at
the completion of the field scan.
Video Motion Detection: A feature that uses the video signal from a camera
to determine movement (pixel changes) and react by recording the video or
setting an alarm condition
Video type lens: An auto-iris lens type that does not use an internal
circuit to control the iris. All iris control signals come from a circuit located
within the camera.
W
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WAN: Wide Area Network; A communications network that
uses such devices as telephone lines, satellite dishes, or radio waves to span
a larger geographic area than can be covered by a LAN
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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.
Have
questions: Contact AMA Security at
800-417-2113 or
email: sales@amasecurity.com