KOSARAM
Kosaram üres

Videó megfigyelés

Alapok

A CCTV rendszerek főbb jellemzői, amit elvárnak tőle
The acronym CCTV comes from the words: Closed Circuit TeleVision.
Video surveillance represents a part of CCTV technology linked with video monitoring of various places to improve security of people and property.
Installation of video surveillance systems requires the highest technical culture and ability to forecast even hardly probable incidents.
In the case of surveillance systems, each installer and user must be aware that devices having too low parameters, 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.
License for surveillance technician / worker.

In many countries, e.g. in Poland, the job of building video surveillance systems requires state or local permits, in the form of license and/or concession.
License - permission for particularly assigned tasks/projects connected with protection of people and objects, necessary for every person and firm offering services in this field. License of the 1st level authorizes the person/firm to build installations, license of the 2nd level enables them to design the systems. Application form for both license types can be issued at the same time. No exams are required - only proof of the knowledge in the field of electronics (e.g. diplomas, degree certificates), as well as in some mechanical disciplines. The police will also formulate their opinion regarding the candidate.
The way of gaining license and concession, required documents and then specimens of license cards are, as an example, shown here in Polish regulations: Regul. MSWiA.
Concession - permission for economic activities in the range of technical surveillance services. It is only required for companies that offer services in the scope of securing events or objects which are under obligatory security rules, included, as an example, in the Polish law: Act.
Video surveillance systems for security purposes - the norm EN 50132-7. Due to high responsibility, when building such installations it is important to use proven algorithms, so that the solutions used are to be compliant with the above norm.
We recommend the following procedure for implementation of CCTV systems :
  • Study of the requirements of contracting party (customer);
  • Designing of the system;
  • Choice of devices - working session;
  • Installation and system startup;
  • Installation of boards with information on active CCTV system;
  • Handing over the system to the customer;
  • Maintenance (keeping the system working).
Especially important, and often disregarded by customers and installers element of CCTV system is visual information about working surveillance installation - its deterring function may be essential for improving security of the object. Examples of CCTV information boards can be seen in article: Monitoring of London
Surveillance quality. As an example - the Polish Ministry of Internal Affairs (MSWiA) regulation regarding mass events registration concerns only a fragment of surveillance installation requirements. However, significance of the subject allows extending these regulations to other, less important installations.
Lack of detailed guidelines concerning technical parameters of surveillance installations causes many controversies, especially when comparing the bids, therefore it can be very useful to specify basic requirements coming from the regulation.
Technical parameters of surveillance installation for mass events, will also be guidelines for contracting parties and installers of city monitoring, especially in the case of allowing materials, coming form recording, in a court.
Here is (in Polish) the whole regulation:
Regulation by Minister of Internal Affairs (Poland), dated 28-th of October, 2004, concerning the way of recording process of mass events and the minimum technical parameters of voice and video recording devices (Dz. U. Nr 243, poz. 2438)
Functional requirements
There is needed a case study, based on precise functional requirements, even before the start of designing the system. It will allow proper selection of the parameters and the needed devices (taking into consideration both requirements and associated costs).
On the one hand, the company which takes on building an installation should expect - on its own initiative - the answers for the following questions, on the other hand, one who orders the system ought to be sure that a responsible firm shouldn't do anything until they get the information:
12 questions for those who plan to build CCTV installation - a short case study of functional requirements:
  • What types of threats are going to be monitored?
  • What areas are going to be monitored?
  • What is the aim of monitoring individual areas?
  • What is the required level of automation?
  • What reaction of the system should be exercised when individual areas are violated?
  • What reaction time of the system is needed?
  • What are the environmental conditions?
  • What way of control of the system is anticipated?
  • How many simultaneous events should be handled by the system?
  • What range and security level of signal transmission is sufficient?
  • How should be performed training of security guards?
  • What form of maintenance of the system would be accepted and who will be responsible for that?
Above questions were elaborated relying on the base of utility requirements included in the norm: CCTV surveillance systems in security related applications - EN 50132-7 (their wider description - in Polish - can be found here.)
The norm EN 50132-7 describes the processes of designing, building and putting into use CCTV installation. The guidelines included in this kind of document are so important, that it is rather impossible to build good installation without using the rules. Each installer, and everyone who orders the system should study standards of the country where the installation is to be built.
Questions on the basic issues
Local, or global? The use of digital signal processing techniques makes possible Internet transmission - without any range limits. However, it is needed - already in designing phase the project - to reserve specific telecommunications channel and its parameters (for example: bandwidth, fixed IP address). It is important to make decision at which stage the video signal is to be digitalized: in the camera (e.g. web camera), in video web server/s, or in the recording devices (DVR cards, stand alone DVRs). Digital video signal transmission provides new opportunities for remote surveillance of places and objects.
Color, or B/W? Digital signal processing and recording systems allow to use, in the same installation, B/W, color and Day&Night cameras (switching form color to B/W mode at low light). The latter devices are the most popular - they provide color images by day, and B/W at night, often with use of additional IR illuminators.
Color systems allow better observation of details and identification capability, therefore they are used for observations of a crowd in the street, customers in supermarkets etc. However, the cameras are less sensitive than B/W devices, so they generally require better illumination. Spectral sensitivity of B/W cameras comprises infrared range, allowing discrete observation during the night (with use of IR illuminators). The advantages of the both kinds are combined in the mentioned above day/night cameras.
What image quality? Image quality depends on the cameras used, parameters of transmission lines, signal processing methods (mainly compression), as well as recording parameters and visualization methods.
Use of one element/unit with worse parameters decreases capability or quality of the whole system. Standard resolution cameras: monochromatic - 460 lines, color - 380 lines are essential part in observation systems. But in the cases when identification of people or car plate numbers, etc. is required, it should be taken into consideration to employ high resolution cameras - 630 and 500 lines correspondingly.
In wide-area networks, it is needed to pay attention to irreversible video signal deformation related to cable transmission. Generally, when using good copper cable, there is no practical problem with signal quality up to 300-400 m. For longer distances one should consider using video amplifiers. For analog signal transmission and longer distances - over 1000m - fiber optic transmission should be applied.
Equally important is the choice of recording method and the recorder. Digital recording on HDDs allows to keep the same good quality of the recorded material, no matter how many times it is played. However, the type and quality of compression strongly influences image quality.
And finally, the influence of monitors on image quality: the monitor should have at least the same resolution as the best camera used.
Image quality and its testing is described in details in the following article (Polish version only but an interesting set of pictures): Tests of image quality in CCTV systems.
Remotely controlled, or fixed? The capability of observation chosen details of the scene may be a highly important feature of some CCTV systems. Necessity of controlling the lens (zoom, focus, iris) and the actuators changing position of the camera (pan/tilt mechanisms) requires selection of adequate PTZ devices and the control system.
During the system designing process, it should be remembered that installation of another fixed camera may be much cheaper and more reliable solution than implementation of movable, remotely controlled unit (possible failure of mechanical parts and much higher cost of PTZ devices).
Resistance to damage. Some systems are especially exposed to damage, therefore it is important to consider use of special devices, for example: cameras with polycarbonate housings or domes (terminals, drunk tanks). It is also worth installing camouflaged cameras, hidden in e.g. clocks. To increase visually the number of cameras, it is worth deploying dummy ones. It is also essential to secure cable installation that should be protected from cutting. Another important thing is that the system should be resistant to blinding by direct strong light pointed at a camera.