Thermal imaging cameras in video surveillance systems
The use of thermal imaging cameras is no longer limited to buildings or installations critical to the defense of a country, or scientific applications. Cameras of this kind are employed to monitor unlit areas with dense vegetation, various processes in factories, power plants, oil and gas installations, at airports, etc. The best results can be achieved by creating systems consisting of optical and thermal cameras. This is due to different principles of operation and diverse forms of the generated images. An important part of such systems is image analysis. Thermal imaging cameras used for ...
Some ONVIF issues
The development of IP CCTV systems was heavily hampered by the lack of compatibility of devices and low degree of flexibility in terms of future expansion. The users were not able to choose products from different manufacturers, not to mention the integration with other systems. ONVIF (Open Network Video Interface Forum) is an open industry forum aimed at coordinating efforts to set common, global standard for IP CCTV systems.
Universal diagrams of CCTV systems
The case studies present basic CCTV systems, analog, hybrid, and IP. These are examples of video surveillance systems for homes, stores, parking lots, towns.
PoE - IEE 802.3af and IEE 802.3at
PoE (Power over Ethernet) is the name of a number of methods that allow for powering network devices through UTP/FTP cables. This way it is possible to power devices such as cameras, phones, switches, access points, etc.
What is DDNS (Dynamic Domain Name System)
and how to use it?
and how to use it?
Translation of the domain name into the set of numbers is performed by the appropriate DNS server, to which the computer sends a request for the translation of the address. After receiving the response with the numeric address, the computer connects to the relevant computer/server.
The main features required for CCTV systems
In the case of surveillance systems, each installer and user must be aware that devices having too low parameters or not well suited for the purpose may bring threat to life or property. It will also effect in insufficient reliability of the system and frequent servicing problems.
Signal standards and parameters
Video signal used in CCTV is called VBS (video, blanking & syncs, or video baseband signal) and CVBS (composite/color video baseband signal). IP is the acronym of the Internet Protocol, the most popular protocol used for communication in computer networks and the Internet. IP camera is a device producing digital video stream that is transmitted via wired or wireless IP networks. It can be viewed and/or recorded even in most remote locations in the network.
Optimization of CCTV camera settings
When selecting a model of a camera we are usually interested in possibility of adjustments to various operating conditions. Of course, more advanced models have more capabilities, simpler devices keep some parameters fixed. However, in order to be able to take full advantage of the adjustments, please refer to their technical data and user manuals. We are here discussing a number of typical settings having an impact on the quality of the image, both positive and negative. Such knowledge will help you achieve the best practical results of the camera operation. The impact of changes in camera ...
A monitor is a device that changes electric signals to optical information suitable for the human eye. Monitors have to fulfill safety standards, which means that they must have CE certificates. Safety standards describe, among other things, maximum accepted electromagnetic and X-ray radiation levels, protection of the user against electric shock, and protection of the device against surges coming from the power line. Before we choose a monitor, we should pay attention to the monitor's parameters: resolution - capability of showing small details, picture geometry and stability, maximum ...
The market offers a very wide range of security cameras. Which camera to choose? What should determine the selection of the suitable device? What parameters should be adjustable? What is a day/night camera? CCTV cameras can be classified in many ways, for practical purposes the basic classification may be based on the output signal and image resolution: * analog cameras and IP cameras (analog cameras have coaxial 75 ohm outputs providing baseband video signal at the level of 1 Vpp; IP cameras are equipped with video servers with RJ-45 network connectors) * IP cameras with standard and ...
Camera lens - optical component of a camera used for projection of the image onto light-sensitive sensor surface. Focal length - distance from the optical center of a lens (measured along its principal axis) to the image of an object placed in infinity - measured and given in millimeters. Iris - the mechanism of aperture regulation that changes the amount of light going through a lens and falling on the image sensor of a CCTV camera.
H.264 compression - learn and use in practice!
Currently, H.264 compression has become a standard in digital video recorders (DVRs). The most advanced devices enable the user to control the compression ratio and many parameters of the video stream injected into the network. To understand the impact of the changes and the allowed ranges, the users should know the general principles of this video compression method.
Due to security reasons and tendency towards cost reduction (centralized protection of multiple sites), video surveillance centers are often situated in some distance from the protected buildings and places, thus the leading role of high quality video transmission.
The use of wireless transmission technology will significantly extend the scope of surveillance systems towards scattered locations, such as electricity relay stations, waterworks, elements of road infrastructure and many other remote places.
In order to ensure proper work conditions for the protected devices, housings may be equipped with heaters, fans, cooling systems etc., depending on specific environment.
Power supplies and accessories
Improper power supply is often the main reason of faulty operation of CCTV system.
PTZ cameras have the ability to capture the area selected by the operator and zoom in on the interesting object. This operation can be carried out using mechanical means (typical PTZ cameras) or electronically, by selecting a portion of a high definition image from a megapixel camera.
Lighting for video surveillance
Good traditional lighting has many advantages. However, it is visible, so it may be easy for an intruder to avoid the illuminated zones. It is also expensive, requiring considerable amounts of energy.
Video signal can be transmitted in analog or digital form.
Connectors in CCTV systems
Connectors play a very important role in any transmission line. Their construction and quality have direct influence on connection stability, attenuation, return loss, mechanical strength. DIPOL offers a new generation of connectors - compression connectors meeting the most stringent requirements and standards.
Signal amplification is used to compensate attenuation of cables. Attenuation values depend on cable types and their lengths.
Modulators - the junction of CCTV and SMATV/MATV systems
Modulator (or RF modulator) allows conversion of baseband video (or audio & video) signal into RF band that can be received by regular TV sets.
Operational requirements for CCTV systems
The article is based on the resources published by British Home Office. It describes the features of CCTV system which are important for its users. With many years of experience, the Home Office has developed a set of requirements on the use of monitoring systems by the police in various investigations. To be able to effectively use the material obtained through a CCTV system, it must meet the requirements set out below, collected in four sections: Quality, Recording, Export, Playback.
LAN for IP video surveillance
How to design, install, and operate LANs used for transmission of video data (IP CCTV). Video surveillance systems based on IP CCTV devices need adequate IP networks for transmitting video data and providing communication among the devices and computers or transcoders. IP CCTV devices send video or video and audio in the form of data stream, usually compressed in MPEG-4 (SP, ASP, AVC/H.264) or MJPEG format. Compression limits the required band. However, the quality of video and audio strongly decreases with higher compression ratios. Some applications may require full resolution (e.g. ...
Architecture of video surveillance systems based on IP networks
Video surveillance systems classified according to their structure. Video monitoring as one of the most reliable methods of protecting various places. Evolution of the systems in the respect of the equipment used, its functionality, range of operation.
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