How to choose your surveillance cameras? What things should be taken into account when purchasing a surveillance camera? What characteristics must have the video recorder?
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In this section we will explain that things need to know to buy a surveillance camera or another, to get exactly the result you expect from your system video surveillance . To properly visualize different scenes with surveillance cameras , to record them or view them directly on a monitor, we need to consider several things. With each of our security cameras from our video surveillance system we have to be clear:
- – Distance to the object you want to display is located.
- – Extent of the image we want capatar. (ZOOM).
- – Image Quality
To facilitate the selection of surveillance cameras we have included a small guide that will be of great help in selecting your cameras:
Guide to the selection of surveillance cameras
Need to see a scene and know if something is happening? Need to see an event and determine exactly what is happening? Need to see the person and determine exactly who is involved?
It is important that you have clear what will be the use of the surveillance camera to select the one that best suits your needs and you can have a video surveillance system perfect and can feel safe in thinking that their security needs are met and that maximizes your investment by having the right cameras.
TYPES OF SECURITY CAMERAS: You will need to determine what kind of camera you need. Here are some questions to ask yourself: • Are the cameras will be used for indoor or outdoor? • Should be a deterrent or remain discrete? • Do you have preference for any particular design? Several types of surveillance cameras to consider for both indoor and outdoor: PTZ mobile, conventional cameras, mini domes and bullet cameras.
|Surveillance cameras bullet This type of surveillance camera is the best known and most commercialized particular level. These security cameras are characterized by their elegant design, its variety of colors. Most of these surveillance cameras incorporate IR illumination for night vision and can be used indoors or outdoors.|
|Domos mobile surveillance cameras PTZ cameras PTZ mobile security are designed to visualize any surface from all angles. Dome cameras can rotate 180 degrees horizontally and 360 in vertial to see even objects that are just below. They can perform sweeps (moving from left to right), lean (move up and down) and zoom in or zoom out . Like the bullet type cameras monitoring, there are options available for indoor and outdoor. and most of them incorporates infrared illumination for night vision.|
|Conventional surveillance cameras Conventional cameras are composed of the camera body, which carries all the electronics, the lens, which varies with the needs of the installation and the power supply. The advantage of this type of surveillance cameras is that you can set up the goal that best suits your needs, depending on the distance of the object you want to display. Also be installed inside the chamber by a support or mount on the outside with a protective housing. There casings of various types depending on weather conditions, heating, fan …|
|Surveillance dome cameras The main feature of these cameras is their half – sphere shape. These cameras are designed to be installed you directly on the ceiling, and get a call discreet installation without much attention. Cameras are vandal resistant dome security and there are options available for indoor and outdoor.|
VISION FIELD The portion of space that the lens is capable of displaying. To determine the extent of the area that the camera is able to visualize have to correctly choose the focal length of the lens. A surveillance camera with a lens focal length smaller displays more scene and has a wide field of view. Unlike longer wide a target scene and reduces the field of view. In the description of our products measure the optical is given in millimeters. Optijas has fixed 2.8mm, 3.6mm … and optician manuals variables 2.8 ~ 12mm, 50mm 5 ~ … and automatic opticas that regunal alone depending on the object distance. How extensive area needs to see with the camera? Here you can see examples of how lens choice affects the view. Use these examples to decide which view your application requires. Video where you can see the field of view give different lens surveillance cameras . The video is best seen in full screen: RESOLUTION The resolution of an image indicates how much detail can be seen in this. A higher resolution, better definition, clarity and image quality. Security cameras produce lower – resolution images with less detail. A surveillance camera of high resolution can capture a person ‘s face or a license plate in detail within a large area. The longer the area you want to see more resolution you will need to see all the details. If you want to monitor a smaller area and do not need a detailed view, a camera with lower resolution can handle it. Remember that higher resolution images also require larger files that take up more storage space on your DVR. How much definition and detail needed? Then you can compare the different resolutions and level of detail to zoom- in on enrollment. GLOSSARY USED IN VIDEO SURVEILLANCE SYSTEMS, TECHNICAL CHARACTERISTICS AND VIDEO SURVEILLANCE CAMERAS DVRs. Formats CCTV video signal CVBS: This is an analog composite signal, namely in PAL system which is traditionally known as the “analogue” video. This system cameras are simple to install and use coaxial cable to transmit the video signal even allowing distances of 300m Its resolution is measured in horizontal TV lines (TVL). IP: It consists of a digital signal that is transmitted through the IP protocol, by knowing this format cameras such as network cameras or IP cameras. Installation is more complex and requires certain knowledge, on the other hand allows high – resolution video. Its resolution is expressed in megapixels. HD-SDI High Definition Serial Digital Interface is a digital signal without compression for high – resolution video with progressive scan which allows be transmitted via coaxial cable with the same simplicity as in the analog system, but with maximum distances of 100m. Its resolution is expressed as 1080p (2 Megapixel) or 720p (1 megapixel). HD-CVI : High Definition Composite Video Interface is an analog composite video signal capable of transmitting high – definition video via coaxial cable analogously to conventional system. Transmits video, audio and data over a single coaxial cable distances of 300 ~ 500m or use UTP cable using baluns as in the analog system. Image Sensor The “digital” image sensor is the element of the camera is responsible for capturing light that makes up the image. It is a chip formed by a photodiode array sensitive to light (pixels) that when exposed capture the photographic image, converting light into electrical signals that are an electronic representation of the image. The most common types of sensors are CCD and CMOS, sizes, measured by its diagonal, 1/4 “and 1/3” inch CCD sensors carry charge through the chip to an analog-digital converter converting the value of each pixel into a digital value (0 or 1) measuring the load that arrives. On the other hand, the CMOS sensors contain many transistors in each pixel and the digital conversion process occurs in the structure of the sensor, so an additional converter is not required. Digital signal processor or DSP chip that processes the digital signal from the digital image sensor. It is often associated with a converter which leaves the signal in the format set: CVBS Analog, IP, HD-SDI, HD-CVI. Some DSP incorporate a displayable OSD (On Screen Display or OSD) that lets you set the parameters and camera settings, either through a built -in joystick button-or through a command additional UTC control connected to the output the camera. There are several DSP’s widely such as the Sony © Effio-E or quality Effio-P 960H. Other models incorporate CMOS processing image sensor such as Pixim © with known Ultra WDR Real, achieved by processing each pixel individually own. Smart Control infrared or IR Smart consists perform intelligent processing of lighting and coverage infrared night vision., So that an image with illumination is achieved IR uniform, burned areas (overexposed) in the center, or dark areas in the contour. Enhanced ringtone or ATR / ALTM Reproduction The ATR makes an improvement of tones by adjusting the specific contrast of each colored area considering information luminance compensating degradation tone due to the existence of very bright areas or dimly lit within of the same scene. The ALTM is a tone mapping method which improves transitions and gradations between light and dark areas “improving” the dynamic range of the camera. Automatic white balance or AWB and ATW Adjusts automatically white balance, ensuring that colors are reproduced with greater accuracy, while the ATW function automatically keeps track of the lighting conditions of the scene and its variation, making continuous adjustments to white balance (tracking). Compensation backlight or BLC cameras have more limited than the human eye dynamic ranges, making it difficult playback transitions from dark to bright with sharp contrast. The BLC reduces this effect by making adjustments to brightness and contrast to achieve the object of the dimly lit area is discernable. Wide dynamic range or WDR / DWDR / HDR function WDR solves the problem of the limited dynamic range using techniques such as using different exposures so they can see objects illuminated areas like the dark. It is called DWDR or Digital WDR when compensation is performed by a digital approach that analyzes the different lighting zones image while talking about WDR Real when the camera has means for, really, two sacks of the same scene with two different exposures, one adapted to the bright area and another to the dark area, using both to produce the final image. The HDR or High Dynamic Range presents a considerable improvement in high – contrast transitions. Noise reduction or 2D-NR / 3D-NR / NR Smart- Noise is a residual part of the signal that is unrelated to the captured light and therefore the original image. 2D-NR function performs a noise suppression in the frame, while 3D-NR also includes comparing one frame to the next (temporal comparison), which is very effective in scenes with little movement where successive images are very similar . In the Smart-NR camera selects one type or another as appropriate. IR CUT or ICR filter A filter IR CUT is a mechanical and movable component that is placed against the lens in order to prevent penetration infrared light distorts visible colors in day mode and automatically removed when necessary the camera works in night mode with IR illumination the result is more vivid color and therefore a higher quality image automatic gain Control or AGC Adjusts the gain of the image electronically amplifying the signal getting a clearer picture, but in return, remember that the signal carries a background noise is also amplified by this method. DC Auto Iris or Iris consists of a device direct control over the iris opening so that the camera can control the light striking the sensor. AE or AE / AES is an automatic electronic control that allows the sensor to vary the shutter speed (shutter) of the chip to accommodate the average illumination of the scene, so that by increasing the shutter speed chip collects less light but the picture is more fluid and the decrease will have greater sensitivity to light but will hurt the movement. Digital Slow Shutter or Sense-Up Increases the average scene illumination considerably, even in very low light conditions (0.00035Lux), but penalizes the fluidity of movement, it follows that works very well for static images but it will compromise where fluency and clarity of moving objects is important. Privacy Mask or Mask is sometimes necessary to hide areas of the scene that should not appear in the recording and for this, some cameras have the function included in the image opaque areas in front of the area to be accurate mask. Compensation of strong lights or HLC This feature allows us to hide or obscure the strong glare produced by the spotlights bright light making an investment in the brightness of the image completely dark areas that were previously white with focus effect, so that glare does not affect the rest of the image. Mirror Mirror o / Flip The different installation positions of the cameras cause sometimes we obtain inverted images and to fix the camera is incorporated into a function that inverts the image vertically or horizontally.