CCTV - CAMERA SYSTEMS

Camera systems have been from the beginning of its inception regarded as one of the most effective security methods and the fact that all the time nothing has changed, indeed quite the contrary. Thanks to technical progress been a significant improvement in parameters of all components. Currently available are normally able to see the cameras in almost complete darkness. This semester in the field of analog sensing extends the possibilities of using camera systems and allows them to deploy applications more unthinkable.

CCTV systems are in early 90th years nothing changed. It was still used the same concept: camera - coaxial line from the camera to a VHS video recorder, or by multiplexers or nut. Viewing was always available only in a single location and only prepared the way before - on analog monitors. Topology of the Star and the system is already in principle require regular servicing. For each camera has been built and used various leadership VHS video. These systems, called Systems 1 generation.

With the advent of the Internet and the massive expansion of computers in the 90 the last century there began to change, and change the world directly revolutionary camera system. The product is now known by the acronym DVR (digital video recorder or digital). Acceptance of compensation VHS tapes or computer hard drive tape drives, shows that the principle of building camera systems is to change. With the use of more CCTV DVR can be more cameras to record without service. DVR, essentially combines multiplexor for record more new cameras and recording devices to record hundreds of hours of video, allowing further extension of CCTV systems. DVR systems for its roughly 10th Annual permit the development of a very comfortable approach to recording and sharing in computer networks and the Internet. Star topology systems. But there is still an important limitation, and thus the need construction management from the camera to the recording equipment. This last flow line with a camera system 1 generation becomes the largest. Achilles heel of camera systems, 2nd generation and is the reason for their leaving and the transition to a new generation, in order for the third. System 3 generation is completely built on the principles of the Internet and the IP protocol. The system does not require the need to build a reserved route for the line from the camera to the recording device and then the end user. Topology camera system 3rd distributed generation is the type of star. The most important part of these systems is a data transmission network operating with TCP / IP. System 3 generation is characterized by the use of commonly available.

IT components as active devices, servers and recording equipment

The camera systems 3 generation of leadership there is reserved. Connecting the camera to the recording devices used in conjunction with other technologies using Ethernet. The aim is to build a separate line for each camera, but due to the fact that it is a technology for IP data transmission allows use of virtually arbitrary line. Outside the most widely used metallic wiring structured wiring category 5 and above is just to connect to an existing distribution lines for telephone lines (Home Ethernet), the classic divorce 230V or 400V (technology called power line), the optical lines (MM and SM), the laser or infrared connections or wireless technologies for data transfer (WiFi). As a recording device is a computer system 3. generation, its disk arrays offer a potentially unlimited capacity for recording. For access to use all available equipment and technology to enable data access. You can browse to your desktop computer, PDA or a mobile phone. Access to recorded data from the camera system, then the is a local matter, but thanks to the Internet as a global scale to data access virtually anywhere. The most important benefit of camera systems, 3rd generation is their flexibility. All parts of the system (procurement of image - camera signal transmission - data network, processing / storage - PC server signal tracking - local area network / internet monitoring - a desktop computer) makes it possible overlapping and combining technologies. That is why the IP camera systems 3 generation at the beginning of his winning campaign. Sharing the driving signal from the camera allows for a more significant savings particularly in building large camera systems. The possibility of multiple listings to ensure and improve safety and reliability or ability to access files through local networks and the Internet allows the use of camera systems not only for security but it also for tracking purposes. All components for camera systems 3 generation is here and begin to implement successfully. In the camera systems we already have the door wide open for the future.

Transfer of video in digital form:

Let us, therefore, the signal transfer speed for analog systems. For color television signals with resolution corresponding to the maximum resolving power of the CCIR systems and 10 bit for the "depth" as the brightness, the color signal and the transmission rate of 25 frames per second must count data flow 8.8 x 25 = 220 Mb / s. When comparing this value with data rates that allow different transmission media, we find that continuous video transmission in uncompressed format and full resolution, the idea with respect to the state of the science and technology for the first time putting the camera CCD chip on the market, and indeed even today - with the exception of ATM networks, asynchronous quickly in whole unrealistic. Only the development of digital technology to higher capacity storage media to a higher speed of information processing, and especially the development of algorithms for data compression enabled massive advent of digital CCTV.

Data compression:

All video compression procedure is common to eliminate redundant and unnecessary details of the image. Extra information identifying the type of digital image in a line Offset rectangular grid of pixels. It represents the neighboring image points very often the same brightness of colors. This means that relevant information is already available, but is mostly multiple repetition of the description of the scope of a given brightness and color shades. Effective description of the redundancy can be eliminated, nor could any observer recognized the difference. An example might be transmitting video cameras with motion picture in pickup scene. Sequence of images always describes the same information content. You thus send the information to the recipient that nothing has changed, and repeat the receiving Party is still the first of a sequence of images. This will significantly reduce network traffic, nor would an observer noted a deterioration of image quality. Reduction of unnecessary information that can be perceived by an observer, based either on a psycho physical properties of human vision, information, or are outside the observer's field of interest, such as. hues in the background scene. Classification of different types of information, but can not be transferred in whole, without error, therefore, may also coder some relevant information distortion. The reconstruction of the encoded image so the picture may appear so. artefacts - the consequences of a coding error.

Compression Standards:

M-JPEG

It offers a standard approach to images, the relative economic hardware available in the expanded safety applications for archiving. However, it is standardized, no transfer format, the risk of incompatibility. The actual resolving power is not standardized, the format used with CIF resolution 352 x 288 pixels. Principle of operation: This is an algorithm based on DCT, a procedure that uses the same image. Put simply, there is the following sequence of events:

DCT algorithm removes redundant data.
Quantization DCT coefficients using a weighting function for the optimization of human vision.
Data is encoded to be minimized entropy quantized DCT coefficients.
Entropy coding is transferred coder with variable-length Huffman-type words.

M-JPEG uses the coding method based on quadratic blocks of 8 x 8 pixels, which cover the entire picture. Council producer of the CCTV systems using this method. One fundamental disadvantage of the method M-JPEG is that the image is decompressed DCT after the re-encoded, provides the picture much worse than it answered calculation unless it is synchronized. The reason is that blocks of 8 x 8 pixels contain high frequency components which undesirably compressed. Other standards are: MPEG, H.261, Wavelet.

Device for processing video signal:

Device for processing video signals come under the influence of the development of digital technology for about the greatest expansion. Periods when the cameras were withdrawn by the frequency switch, where the potentiometer set the time for individual images, with the exception of the simplest low-cost systems irretrievably gone. Bomb was at the time of a device more cameras on one monitor - quadrant selectors. CCTV systems cheaper, although that was not necessary to use several monitors for systems with a permanently staffed allow parallel monitoring of multiple camera angles, in practice, however, due to the impact of human factors increased the effectiveness of camera systems. The ability to track people over long-term physiological processes is limited.

The real coup was putting multiplexed devices, which themselves are associated features an intelligent switch, multiple quadrant selector for multi-image display. Moreover, the problem addressed by the previous generation devices have failed to solve - a continuous record of more cameras with minimal dead time in a single TL VCR. Here was a real image capture, more or less output for re-entry was in an analog standard CCIR / PAL with a resolution for best record in the TL and in Standard VCR S-VHS.

Video signal processing equipment is now well video server that allows connection of one or more analog CCTV cameras, other peripherals. It converts and compresses an analog signal from connected cameras to digital form and is connected to the network (LAN, WAN, Internet), some Video server in each pool also feature a local digital recording equipment. Allows remote control from anywhere a network of PCs equipped with the software. It is these devices change the entire philosophy of design and construction of large CCTV systems.

ESPRIT

The introduction of new technology in production constantly brings new features and new components that are faster, more sensitive, dimensional, of course, are smaller and longer life one of such innovations is also special board cameras ESPRIT. Most professionals in CCTV has met with this product, or at least heard about it. His description. The key word in making this article the word 'integration' It is in fact an integrated camera positioning system, which consists of a camera housing with an integrated set of optical, compact head positioning with high performance and integrated telemetry source and interface for inputs and outputs of the camera. When choosing a particular model of the Esprit Board can choose from several options.

Other models are already equipped with cameras with high image resolution with an automatic night mode, the lenses may have 18 or 22 x optical zoom. (0.013 to 0.07 lux). The sensitivity of the integrated camera is designed to be able to capture images and scenes studied under adverse lighting conditions, and without IR lighting. Esprit Board IOP is possible to add the extra programmable automatic windscreen wipers. All functions of the camera and lens with this new board is adjustable by remote control keyboard, so using the system as needed, at any time to change the current setting.

Through on-screen camera menu you can configure the entire range of functions, such as. Sensitivity auto focus, iris control, filter, etc. Ir. In practice this means that after installation Esprit of opinion and you end up involved for all the external work that can be, depending on weather and local conditions, not only very uncomfortable, but also time-consuming and costly. Impressive is also the technical parameters used for the rotor, which allows continuous (360 °), proportionally controlled rotation in the horizontal plane, the speed from 0.1 to 100 ° / s. swivel range in the vertical direction is -90 to +40 °, speed 0.1 to 20 ° / s. system may be due to the high climate resistance and deployed in a very exposed positions. Operating temperature range -45 to +50 ° C and wind speed can reach up to 145 km / h. Esprit all types can be controlled through various protocols and devices.

Camera systems for small and medium-sized cities

Security in the city - the legitimate concerns of their residents Finding safety of the people in towns and villages is currently received on a of the leading cities between the requirements of local government authorities. This authorized requests, to date more or less successfully solved only in larger cities where there is gradually built up relatively expensive camera surveillance system. Most advanced camera systems and in smaller towns and villages while still preventing their relative high price.

DISS SECURITY LINE - camera system with low cost appropriate for medium and small cities. The rapid development of CCTV products, technology and the advent of digital systems in this area still offers new opportunities and their application in practice. Digitization allows devices today unconventional design new complex systems, which price is much lower than conventional analog price. And at the same or even better functional properties. One of the system to the maximum extent using digital CCTV technology, is a comprehensive camera system DISS SECURITY LINE especially suited for medium and small cities. It is based on wireless transmission of digital video in the free frequency band 2.4 GHz. The system is capable of transmitting antenna using one frequency channel images of more cameras (max. 16), including the management command to rotate the camera. Until recently used systems using copper or fiber lines. These systems were priced very difficult because the technology required to build underground or difficult overhead cable routes. With greater or lesser success as a compromise began to be used in the recent past analog wireless transmission systems, but they have some disadvantages.

Digital wireless video as a solution

The main advantages of DISS SECURITY LINE include:

Low cost and low transfer costs
It is a complete a complex CCTV system
2.4 GHz bandwidth is free and free, does not require any license or Registration
Maximum impact of service is 2 to 5 km
Digital transmission over analog video signal is stable, subject to the influence environment, do not disturb it any other broadcast systems, vehicles and so on.
The system is secured against unauthorized misuse of broadcast encryption Video
Management rotating camera can be done with a control console with joystick
Management rotating cameras is performed in real time without time delay
The possibility of parallel duplex audio
The possibility of parallel complementary duplex data transfer
There is no need to use two transmission systems for rotating the camera, as in analog systems
A single transmission channel can transmit video from up to 16 cameras
The system allows you to connect more clients simultaneously
The system is a digital recording unit (DVR) with a recording capacity of 80 -- 480 gigabytes

Compression

Only scanned and raw (uncompressed) images take up an enormous amount Storage space on tape or disk. Each picture contains more than 650 KB (color CIF) information. This information must be compressed to a readable size, which will reduce the size of the required storage space. Compression will reduce the size of the data stream and then can transmit the images to telephone lines or via a computer network. Video compression process is generally stable in two stages. The first stage, which is optional, reduces the resolution of the digitized input video. In some cases, the customer calls for doing so, although in some cases reduction of the full one-fourth resolution (eg 352 x 240, known as the CIF) may be acceptable. Similarly, in video images containing the luminance color component may be a component of double differentiation reduced.

In the second stage of compression algorithm is applied to reduce the resolution of digital video. To this end, it is possible to use many different algorithms that we describe below (JPEG, MPEG H.320, Wavelet). The techniques may be different compression algorithms on the basis that they make so. inside-frame or inter-frame compression. Inter-frame algorithms such as JPEG compressed digital image of each such single unit. Removing redundant information - eg. the adjacent pixels in the image are identical or very similar color, and can therefore be removed.

Between-frame algorithms such as MPEG and H.320 compressed each image based on differences between successive images. Removes the similarity between pictures ride behind. The interior frame algorithms are capable of producing compressed video with high quality, but on behalf of large files and large data flow. Or conversely seek to significantly reduce the size of the data with somewhat lower quality video. Between frame algorithms try to detect changes resulting from the movement, and other information are considered redundant. These compression methods are referred to as "loss". This means that the compression algorithm "loses" some information from an image in order that compression is effective. The resulting image is not exactly the same as the original. This loss of information is inadmissible, but it affects the creation issues, whether such. digital recording can be used as evidence. Analog video is also a loss, and many details are lost when the record is used only to VHS videotape or tape is used much more than is recommended.

Compression ratios

Each compression method has its own distortions. Hours are from imperceptible to intolerable, depending on the compression ratio used. Used "loss" compression methods are able to remove anything between 90 to 99% of picture information. The compression ratio of 10:1 to lose 90% of data at 100:1 ratio is 99% of the data. Professional Industry (Broadcast) seeks to use the compression ratio of 3:1. many manufacturers compresses its Figures in the compression ratio of about 10:1 to 20:1 and still achieve very good image quality. So more than 650 KB of data a single color images (CIF) compressed in the ratio 15:1 for the record and reduce transmission to about 44 KB - already makes a very significant difference.

Compression method

There are many different kinds of compression methods. The security industry frequently used by JPEG, MPEG, H.320 and Wavelet. Other methods can be used eg. fractals. Fractal compression but the process takes much time image compression, it is not industrial standard, and therefore her application in the field of security does not count. Compression JPEG and MPEG methods used for image compression technique called discrete cosine transform (DCT - Discrete Cosi Transformation). However, each image divided into blocks with 64 (8 x 8) pixels. Each of these blocks are then individually analyzes the exclusion of unnecessary details and then performed compression.

JPEG compression

JPEG (Joint Photographic Group under the Expert Group) is the oldest and recognized compression method, which is included in the ISO standards. JPEG compression uses poor isolating and removing excess spatial information of each image or series of images. JPEG is designed by using the known limitations of the human eye, namely that small color changes are perceived less as small changes in luminosity. A useful feature JPEG is the possibility of setting different compression ratio, which may change the level of losses. It also has an impact on the output file size versus image quality. The JPEG compression is used for the above mentioned DCT - digital image divided into blocks of 8x8 blocks of pixels. Each block is then marked with a coded number. Software tested these units and decide which of them are redundant and therefore irrelevant for an image. It thus transmits only those blocks that are necessary, thereby reducing their number depends on the basic level under compression system settings. Large JPEG image compression level causes loss information leading to the final picture as if folded into a mosaic of squares. JPEG can be identified as M-JPEG (Motion-JPEG), ie motion JPEG. This intends that, in essence, the principles can be applied to JPEG motion video similar to still images or individual images. It should be noted that there is no industrial standard for M-JPEG. JPEG is also some manufacturers known as the "MPEG - I Frame Only".

MPEG

MPEG (Moving Pictures Expert Croup) is a group of standards for coding audiovisual information, digital compression format. The compressed files are removed from the data in time redundant and irrelevant information. The biggest difference with JPEG is the way of analysis and Signal Compression: MPEG is the individual images are processed separately, but are compressed the whole sequence. The data of several consecutive frames are processed simultaneously in direct connection with the following.

The idea behind this compression is a record number of key frames, which are actually coded still images (JPEG images) called "I-Frame" - respectively. between images and prediction of movement of the slide images in the time domain. Consequently, the DCT algorithm is applied Selection redundant circuit elements. DCT is performed on blocks of 8 x 8 pixels, and motion prediction is performed in the luminance (Y) channels in blocks 16 x 16th Between I - The imagery is 12 images. The higher compression ratio looks more and more "cube", as in the actual JPEG compression. In decompression, the data for a series of pictures selected from the key frames. Information on the I-frame images are used as a basis to create images that are occur between them. The advantages of this technology is significantly more efficient compression, we need much smaller amount of data in differential images, and hence less recording space to achieve the same or even better video quality than JPEG. MPEG compression is at least 10 times more expensive than decompression.

MPEG is based on the redundancy between the rapidly moving video images, is very suited for industrial applications lance television. Comparison and processing information between key imagery creates a small time lag. It is about 1 to record the real-time, but it is multiplied by the record in Roll mode. When the camera switches quickly, so find MPEG codec can compress and redundancy in the time domain. For applications with a small amount of data is fast-moving images fully redundant. In such cases it is preferable to record the compressed images based on one type of movement detection. There are different types of MPEG. MPEG-1 has low resolution and can not achieve the quality standard VHS video. It is also able to compress the higher compression ratio than JPEG or wavelet, only images at a resolution of 320 x 240 or less. MPEG 2 is able to process images in full resolution and is currently used for professional purposes, eg. for broadcasting and DVD production. The higher compression ratio of MPEG images are starting to look "cube" and the screen are more artifacts than as a separate JPEG compressed. Other versions of MPEG are currently used in the security industry.

H.320

This group of video compression is often used for applications like video conferencing and in some products. The security applications are also used primarily in systems with remote access, a video transmission via telephone lines and computer networks. The technology is very similar to MPEG, transmits only the pixels of each image that have changed over the previous. Because two consecutive images from the camera are usually very similar, so after using the differential technique fps are sent only to the differences between individual frames. The main disadvantage of this method is that the total change of scene or camera switching, the range of data immediately rises, and the resulting image quality is strongly reduced. If you switch camera, so it's a very good choice for video compression and transmission.

Wavelet

Like the JPEG and MPEG, and wavelet compression has several different types of and shoots. This type of compression algorithm is not yet industrially standardized, therefore the quality of coder and decoder is very different from one product to another. Wavelet technology standardization both in 2001 as ISO 15444, because the core structure of the forthcoming standard JPEG 2000 is based on a new wavelet compression method. Waves are essentially mathematical expression of the encoding picture in continuous flow, thus preventing visible artifacts, such as sharing the results of DCT image compression in discrete blocks. Wavelet compression offers higher data reduction with better image quality than JPEG compression.

Video Compression Wavelet working with parts of the image, but operates on the entire image at once. Transform uses a series of filters that determine the content of each pixel in the image. The outputs of all filters will create a set of coefficients, which is the result of filtration. The frequency filtering across the image or half-width removes all information with high frequencies. Maintain a low frequency of forming part of the picture, which sees more than the human eye. Because the human eye is able to recognize high frequency, which is reflected most in color, so this information can be removed without obvious differences.

Wavelet Technology is working with the whole picture, so there is no apparent emergence of mosaic effect. Wavelet "sleek" reduces image quality to increase compression ratio. Compression ratio for video applications can be run and specify where necessary. Images compressed wavelet technology looks very good when they appear as a small window on the screen. Only when the full-screen magnification, the quality deteriorates. Wavelet is one of the others' loss-making "methods (JPEG, MPEG). Although the resulting images at high compression ratios (140:1) without boxes, so the picture with great depth and detail may lose any important information. However, in applications where it is important as high levels of detail by using Wavelet use high compression ratios - are able to record a video disc for the whole week or month. Therefore, a device using this technology can be an inexpensive and effective solution.

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