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| Monitoring cameras Selection and Procurement Guide
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With the monitoring system in the community more widely applied, for the type of
monitoring cameras (brand, type and model) the growing proliferation. As the
installation of the monitoring project design, so many types of cameras, their
system designers and purchasing managers, is a test. How can the correct choice
of cameras, to ensure that the best system, the system's lowest cost? These
problems are many design engineers and purchasing managers.
Perhaps this
article, the problems facing the engineers help and inspiration. In order to
properly on this issue, let us start with some basic knowledge of CCD camera
about it:
1, CCD camera monitoring classification
1, depending on color
imaging division
Color monitoring cameras: to identify detailed features,
such as clothing or features to distinguish the color.
Black and white
surveillance camera: do not apply to light areas and adequate lighting at night
can not install the equipment, surveillance features only in the location or
mobile, they can choose black-and-white surveillance cameras.
2, in
accordance with resolution sensitivity of
380,000 pixels in the image below
for the general type, particularly in 250,000 pixels (512 * 492), a resolution
of 400 lines of the most common products.
Pixel image in the more than
380,000 high-resolution type.
3, according to the shape of surveillance
cameras
Surveillance cameras on the main form of: the gun-control cameras,
pinhole-monitoring cameras, hemisphere-monitoring cameras.
4, according to
the size of CCD target surface
1-inch - the target size for the width of
12.7 mm * high 9.6 mm, diagonal 16 mm.
2 / 3 inches - the target size for
the width of 8.8 mm * high 6.6 mm, diagonal 11 mm.
1 / 2 inches - the target
size for the width of 6.4 mm * high 4.8 mm, diagonal 8 mm.
1 / 3 inches -
the target size for the width of 4.8 mm * high 3.6 mm, diagonal 6 mm.
1 / 4
inches - the target size for the width of 3.2 mm * high 2.4 mm, diagonal 4 mm.
5, by scanning standard of
PAL system.
NTSC system.
6,
depending on power supply division
220VAC, PAL system.
24VAC.
12VDC,
such an internal camera and more.
6, by way of sync
In sync: the camera
in sync signal circuit in the synchronization signal to complete the operation.
In sync: the simultaneous use of a signal generator, will synchronize
signals into the camera, synchronization input.
Power Sync (linear lock,
line lock): AC power using the camera to promote complete vertical sync.
VD,
simultaneously: the camera signal cables on the VD sync pulse input from VD
complete synchronization.
Across the camera, synchronized: the multiple
camera fixed in sync, so that each can monitor cameras in operation under the
same conditions, due to the camera simultaneously, so even if one video camera
to switch to other features, synchronized camera images do not Will distortion.
Second, CCD camera monitoring basic knowledge of color
1, CCD
color camera monitoring the main technical indicators
(1) CCD size, which is
the target of the camera. Now 1 / 3 inches has been the popularity of the 1 / 4
inches has commercialization.
(2) CCD pixels, the more pixels, the higher
the image resolution, the more clear, now more than 250,000 to 380,000 pixels
and for the demarcation, more than 380,000 pixels for high-definition cameras.
(3) horizontal resolution. Color Camera resolution is in the typical 320 to
500 TV lines between the current market to 420 TVL and 480 TVL resolution of the
two dominant position.
(4) minimum illumination, also known as sensitivity.
Moonlight and Stars-class high-level sensitization of the cameras can work in a
very dark conditions, the general terms of the camera, 2 ~ 3 lux is the most
Minimum illumination, 1 lux camera comparison of general popularity, the most
commonly used.
(5) scan format. NTSC and PAL system with a points system.
(6) camera power. Exchange of 220 V, 110V, 24V, DC for 12 V or 9 V.
(7)
signal to noise ratio. The typical value of 46 db, if for 50 db, while a small
amount of image noise, but the image quality is good if it is 60 db, image
quality is excellent, there is no noise.
(8) video output. For more than 1
Vp-p, 75¦¸ , BNC connectors are used.
(9) Lens installation methods. C and a
CS, two different, because different photographic distance.
Third,
monitoring cameras optional experience
In the monitoring system
applications, the monitoring cameras selection is crucial, it has a direct
decision of the whole monitoring system for images. Below, on various occasions
we talk about the choice of camera view, for your reference.
Selection of
cameras based on two factors: First, the camera use of the environment
(applications); First, the main parameters related to the camera.
A) camera
surveillance cameras monitor applications - the choice of type
At present
the camera a wide range of applications is also different. Applications decided
type of camera selection, it is necessary to choose the right camera, we must
understand the installation of the cameras occasions to determine the
installation type. At present, the cameras installed applications are: offices,
hotels, factories, banks, prisons and so on. General also divided into indoor
and outdoor use.
We monitor the installation to the hotel as an example to
illustrate the choice of the camera. Under the current practice, the hotel
application monitoring system, front-end cameras installed location are: lobby,
elevators, corridor corridors, parking lots.
Installation location
monitoring demand characteristics of the reasons for choice of optional camera
type
Parking control of large, dynamic integration of the camera (such as
BN-132WD)
Or gun-type camera + electric built-in zoom lens camera
integration for large dynamic range of occasions, the site details can be
enlarged, but also simple to install debugging.
Monitoring of the hall, a
dynamic integration of the camera (such as BN-132WD) Ibid.
Elevator
monitoring of fixed and stable flying saucer light cameras
(BN-030HUFO)
elevator installation location is narrow and small hemisphere installed cameras
and difficult to put stem from customers, the lift can take into account the
overall appearance and image monitoring results
Monitoring of the fixed
corridor corridor, a more stable blast hemisphere light cameras (BN-0340HHL)
lower ceiling of the hotel, such as lifting the general gun-type camera, too
eye-catching decoration effects of the destruction of the corridor. Xiding
hemisphere installed cameras and can take into account the overall aesthetic
corridors and monitoring results, but also simple to install debugging
B) monitoring cameras optional parameters
Selected monitoring camera
type, we should also determine the environment for application specific
parameters of the camera and then selected camera models. Generally speaking,
the camera's main parameters are: clarity, the Minimum illumination, and the
remaining parameters for reference.
Definition: currently available camera
330 TVL --- 480TVL majority, according to the application of now, 420 TVL
cameras of the most universal, 480 TVL application of high-definition cameras
followed;
The Minimum illumination: Minimum illumination of the camera work
is the minimum requirement of the surrounding environment. Therefore it is also
an important choice of camera parameters.
We still control the hotel as an
example, a selection of camera parameters:
Monitoring parameters require
installation location optional camera type selection reasons
Parking
requirements of high-definition, the integration of environmental changes in
brightness camera
(BN-132WD)
Or day and night-gun-type electric zoom
camera +
BN-132WD resolution of up to 520 TVL, built-in automatic lens
aperture for the camera, suitable for brightness changes
Monitoring of the
hall, the integration of dynamic camera
(BN-132WD)
Ibid.
Monitoring of the elevator fixed, light stability, large and small angle
camera hemisphere
(BN-030DUFO)
Elevator internal lighting installed,
the brightness changes little, we choose 0.01-1 LUX illumination cameras, 420
line on the line, targeting 3.6 mm wide-angle lens
Monitoring of the fixed
corridor corridor, a more stable hemisphere light cameras (BN-0340DHL)
Lighting installed within the corridor, so little change brightness, we choose
0.01-1 LUX illumination cameras, 420 line on the line, configuration 8 mm
wide-angle lens
C) monitoring cameras suitable for all types
of applications
Below give some type of surveillance cameras the most
appropriate applications for use by engineers to monitor the system design
reference:
Camera types of applications
1 hemisphere cameras
Elevator, a little change ceiling light indoor applications
2 integrated
video camera installed in the most suitable for indoor greater dynamic range
control of the occasion, also suitable for installation in the middle-range
outdoor monitor the occasions (for monitoring outdoor 60 m within a radius of
the target)
3 gun-type camera can be installed in any indoor occasions, but
not suitable for the installation of monitoring or smaller occasions
4
underwater camera for underwater installation
Five days and nights of the
camera applies to environmental changes in brightness larger occasions, such as
indoor and outdoor lighting at night is weak, the normal brightness of occasions
during the day
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