| 01.AGC |
|
| Automatic gain control. A section
in an electronic circuit that has feedback and regulates
a certain voltage level to fall within predetermined margins |
| |
| 02.ALC |
|
| Automatic light control A part
of the electronics of an automatic iris lens that has
a function similar to backlight compensation in photography. |
| |
| 03.Aperture |
|
| The opening of a lens that controls
the amount of light reaching the surface of the pickup
device. The size of the aperture is controlled by the
iris adjustment. By increasing the F- stop number( F /
1.4, F / 1.8, F / 2.8, etc.) less light is permitted to
the pickup device. |
| |
| 04.Auto iris ( AI ) |
|
| An automatic method of varying
the size of a lens aperture in response to changes in
scene illumination. |
| |
| 05.Back-focus |
|
| A procedure of adjusting the
physical position of the CCD - chip / lens to achieve
the correct focus for all focal length settings (especially
critical with zoom lenses). |
| |
| 06.BNC |
|
| BNC stands for Bay9onet - Neil
- Councilman connector, and it is the most popular connector
in CCTV and broadcast TV for transmitting a basic bandwidth
video signal over a coaxial cable. |
| |
| 07.Brightness |
|
| In NTSC and PAL video signals,
the brightness information at any particular instant in
a picture is conveyed by the corresponding instantaneous
DC level of active video. Brightness control is an adjustment
of setup ( black level, black reference ). |
| |
| 08.CCD |
|
| Charge-coupled device. The new
age imaging device, replacing the old tubes. When first
invented in the 1970s, it was initially intended to be
used as a memory device. Most often used in cameras, but
also in telexing, fax machines, scanners, etc. |
| |
| 09.CCIR |
|
| Committee Consultative International
des Radio communique or, in English, Consultative Committee
for International Radio, which is the European standardization
body that has set the standards for television in Europe.
It was initially monochrome; therefore, today the term
CCIR is usually used to refer to monochrome cameras that
are used in PAL countries. |
| |
| 10.CCTV |
|
| Closed circuit television A television
system intended for only a limited number of viewers,
as opposed to broadcast TV. |
| |
| 11.C-mount |
|
| The first standard for CCTV lens
screw mounting. It is defined with the thread of 1" (
2.54mm ) in diameter and 32 threads/inch, and the back
flange-to-CCD distance of 17.526mm ( 0.69" ). The C-mount
description applies to both lenses and cameras. C-mount
lenses can be put on both C-mount and CS-mount cameras,
only in the latter case an adaptor is required. |
| |
| 12.Coaxial
cable |
|
| The most common type of cable
used for copper transmission of video signals. It has
a coaxial cross-section, where the center core is the
signal conductor, while the outer shield protects it from
external electromagnetic interference. |
| |
| 13.CS-Mount |
|
| A newer standard for lens mounting.
It uses the same physical thread as the lenses made smaller,
more compact and less expensive.CS-mount lenses can only
be used on CS-mount cameras. |
| |
| 14.dB |
|
| Decibel A logarithmic ratio of
two signals or values, usually refers to power, but also
voltage and current. When power is calculated the logarithm
is multiplied by 10, while for current and voltage by
20. |
| |
| 15.DSP |
|
| Digital signal processing. It
usually refers to the electronic circuit section of a
device capable of processing digital signals. |
| |
| 16.EIA |
|
| Electronics Industry Association,
which has recommended the television standard used in
the U. S¡FCanada and Japan, based on 525 lines interlaced
scanning. Formerly known as RMA or RETMA. |
| |
| 17.F-number |
|
| In lenses with adjustable irises,
the maximum iris opening is expressed as a ratio ( focal
length of the lens )/( maximum diameter of aperture ).
This maximum iris will be engraved on the front ring of
the lens. |
| |
| 18.Focal length |
|
| The distance between the optical
center of a lens and the principal convergent focus point. |
| |
| 19.Gain |
|
| Any increase or decrease in strength
of an electrical signal. Gain is measured in terms of
decibels or number of tines of magnification. |
| |
| 20.Gamma |
|
| A correction of the linear response
of a camera in order to compensate for the monitor phosphor
screen nonlinear response. It is measured with the exponential
value of the curve describing the non-linearity. A typical
monochrome monitor's gamma is 2.2, and a camera needs
to be set to the inverse value of 2.2( which is 0.45 )for
the overall system to respond linearly ( I. e; unity ). |
| |
| 21.Gen-lock |
|
| way of locking the video signal
of a camera to an external generator of synchronization
pulses. |
| |
| 22.Horizontal resolution |
|
| Chrominance and luminance resolution
(detail) expressed horizontally across a picture tube.
This is usually expressed as a number of black to white
transitions or lines that can be differentiated. Limited
by the bandwidth of the video signal or equipment. |
| |
| 23.IR light |
|
| Infrared light, invisible to
the human eye. It usually refers to wavelengths longer
than 700 nm. Monochrome (B / W) cameras have extremely
high sensitivity in the infrared region of the light spectrum. |
| |
| 24.Iris |
|
| A means of controlling the size
of a lens aperture and therefore the amount of light passing
through the lens. |
| |
| 25.Lens |
|
| An optical device for focusing
a desired scene onto the imaging device in a CCTV camera. |
| |
| 26.Line-locked |
|
| In CCTV, this usually refers
to multiple cameras being powered by a common alternative
current (AC) source (either 24V AC, 110V AC or 240V AC)
and consequently have field frequencies locked to the
same AC source frequency (50 Hz in CCIR systems and 60Hz
in EIA systems). |
| |
| 27.Lux [Ix ] |
|
| Light unit for measuring illumination.
It is defined as the illumination of a surface when luminous
flux of 1 lumen falls on an area of 1 m. It is also known
as lumen per square meter or meter-candelas. |
| |
| 28.NTSC |
|
| National Television System Committee.
American committee that set the standards for color television
as used today in the U.S., Canada, Japan and parts of
South America. NTSC television uses a 3.57945 MHz sub-carrier
whose phase varies with the instantaneous hue of the televised
color and whose amplitude varies with the instantaneous
saturation of the color. NTSC employs 525 lines per frame
and 59.94 fields per second. |
| |
| 29.Output impedance |
|
| The impedance a device presents
to its load. The impedance measured at the output terminals
of a transducer with the load disconnected and all impressed
driving forces taken as zero. |
| |
| 30.PAL |
|
| Phase alternating line. Describes
the color phase change in a PAL color signal. PAL is a
European color TV system featuring 625 lines per frame,
50 fields per second and a 4.43361875-MHz sub-carrier.
Used mainly in Europe, China, Malaysia, Australia, New
Zealand, the Middle East and parts of Africa. PAL-M is
a Brazilian color TV system with phase alternation by
line, but using 525 lines per frame, 60 fields per second
and a 3.57561149-MHz sub-carrier. |
| |
| 31.Pan and tilt head
(P/T head) |
|
| A motorized unit permitting vertical
and horizontal positioning of a camera and lens combination.
Usually 24V AC motors are used in such P/T heads, but
also 110V AC, i.e., 240V AC units can be ordered. |
| |
| 32.Pan unit |
|
| A motorized unit permitting horizontal
positioning of a camera. |
| |
| 33.Peak-to-peak (pp) |
|
| The amplitude (voltage) difference
between the most positive and the most negative excursions
(peaks) of an electrical signal. |
| 34.Pixel |
|
| Derived from picture element.
Usually refers to the CCD chip unit picture cell. It consists
of a photo sensor plus its associated control gates. |
| |
| 35.Protocol |
|
| A specific set of rules, procedures
or conventions relating to format and timing of data transmission
between two devices. A standard procedure that two data
devices must accept and use to be able to understand each
other. The protocols for data communications cover such
things as framing, error handing, and transparency and
line control. |
| |
| 36.PTZ camera |
|
| Pan, tilt and zoom camera. |
| |
| 37.PTZ site driver (or receiver
or decoder) |
|
| An electronic device, usually
a part of a video matrix switcher, which receives digital,
encoded control signals in order to operate pan, tilt,
zoom and focus functions. |
| |
| 38.Resolution |
|
| A measure of the ability of a
camera or television system to reproduce detail. The number
of picture elements that can be reproduced with good definition. |
| |
| 39.Remote control |
|
| A transmitting and receiving
of signals for controlling remote devices such as pan
and tilt units, lens functions, wash and wipe control
and similar. |
| |
| 40.RG-58 |
|
| A coaxial cable designed with
50-ø[ impedance; therefore, not suitable for CCTV. Very
similar to RG-59, only slightly thinner. |
| |
| 41.RG-59 |
|
| A type of coaxial cable that
is most common in use in small to medium-size CCTV systems.
It is designed with an impedance of 75-ø[. It has an outer
diameter of around 6 mm and it is a good compromise between
maximum distances achievable (up to 300 m for monochrome
signal and 250 m for color) and good transmission. |
| |
| 42.RS-232 |
|
| A format of digital communication
where only two wires are requited. It is also known as
a serial data communication. The RS-232 standard defines
a scheme for asynchronous communications, but it does
not define how the data should be represented by the bits,
i.e., it does not define the overall message format and
protocol. It is very often used in CCTV communications
between keyboards and matrix switchers or between matrix
switchers and PTZ site drivers. The advantage of RS-232
over others is its simplicity and use of only two wires. |
| |
| 43.RS-485 |
|
| This is an advanced
format of digital communications compared to RS-422. The
major improvement is in the number of receivers that can
be driven with this format, and this is up to 32. |
| |
| 44.Signal-to-Noise ratio
(S/N) |
|
| An S/N ratio can be given for
the luminance signal, chrominance signal and audio signal.
The S/N ratio is the ratio of noise to actual total signal,
and it shows how much higher the signal level is than
the level of noise. It is expressed in decibels (dB),
and the bigger the value is, the crisper and clearer the
picture and sound will be during playback. An S/N ratio
is calculated with the logarithm of the normal signal
and the noise RMS value. |
| |
| 45.Twisted-pair |
|
| A cable composed of two small-insulated
conductors twisted together. Since both wires have nearly
equal exposure to any interference, the differential noise
is slight. |
| |
| 46.White balance |
|
| An electronic process used in
video cameras to retain true colors. It is performed electronically
on the basis of a white object in the picture. |
| |
| 47.Y/C |
|
| A video format found in Super-VHS
video recorders. Luminance is marked with Y and is produced
separate to the C, which stands for chrominance. Thus,
an S-VHS output Y/C requires two coaxial cables for a
perfect output. |
| |
| 48.Zoom lens |
|
A camera lens that can vary
the focal length while keeping the object in focus,
giving an impression of coming closer to or going away
from an object. It is usually controlled by a keyboard
with buttons that are marked zoom-in and zoom-out. |