The functions of modern surveillance systems have long gone beyond video recording as such. Detection of movement in the area of ββinterest, counting and identification of people and vehicles, keeping an object in the stream - today even not the most expensive IP cameras are capable of all this. If you have a sufficiently productive server and the necessary software, the possibilities of the security infrastructure become almost limitless. But once such systems did not even know how to record video.
From pantelegraph to mechanical TV
The first attempts to transmit images over a distance were made in the second half of the 1862th century. In XNUMX, the Florentine abbot Giovanni Caselli created a device capable of not only transmitting, but also receiving images over electrical wires - a pantelegraph. That's just to call this unit a "mechanical TV" could only be a very big stretch: in fact, the Italian inventor created a prototype of a fax machine.
Pantelegraph by Giovanni Caselli
Caselli's electrochemical telegraph functioned as follows. The transmitted image was first "converted" into a suitable format, redrawn with non-conductive ink on a sheet of steel (tin foil), and then fixed with clips on a curved copper substrate. A gold needle acted as a reading head, line by line scanning a metal sheet with a step of 0,5 mm. When the needle was over the area with non-conductive ink, the ground circuit was opened and the current was applied to the wires connecting the transmitting pantelegraph to the receiving pantelegraph. At the same time, the receiver's needle was moved over a sheet of thick paper impregnated with a mixture of gelatin and potassium hexacyanoferrate. Under the action of an electric current, the connection darkened, due to which an image was formed.
Such a device had a lot of shortcomings, among which it is necessary to highlight low productivity, the need to synchronize the receiver and transmitter, on the accuracy of which the quality of the final image depended, as well as the laboriousness and high cost of maintenance, as a result of which the age of the pantelegraph turned out to be extremely short. So, for example, the Caselli devices used on the Moscow-St.
The bildtelegraph, created in 1902 by Arthur Korn on the basis of the first photocell, invented by the Russian physicist Alexander Stoletov, turned out to be much more practical. The device gained worldwide fame on March 17, 1908: on this day, with the help of a bildtelegraph, a photograph of the criminal was transmitted from the Paris police station to London, thanks to which the policemen subsequently managed to identify and detain the attacker.
Arthur Korn and his bildtelegraph
Such a unit provided good detailing of a photographic image and no longer required its special preparation, however, it was still not suitable for transmitting a picture in real time: it took about 10β15 minutes to process one photograph. But the bildtelegraph took root well in forensic science (it was successfully used by the police to transfer pictures, identikit images and fingerprints between departments and even countries), as well as in news journalism.
A real breakthrough in this area took place in 1909: it was then that Georges Rin managed to achieve image transmission with a refresh rate of 1 frame per second. Since the telephoto apparatus had a βsensorβ represented by a mosaic of selenium photocells, and its resolution was only 8 Γ 8 βpixelsβ, it never went beyond the laboratory walls. However, the very fact of its appearance laid the necessary foundation for further research in the field of image broadcasting.
The Scottish engineer John Baird really succeeded in this field, who went down in history as the first person who managed to transmit an image over a distance in real time, which is why he is considered to be the βfatherβ of mechanical television (and television in in general). Given that Baird almost lost his life during his experiments, receiving a 2000-volt electric shock while replacing a photovoltaic cell in a camera he created, such a title is absolutely deserved.
John Baird, inventor of television
Byrd's creation used a special disk invented by the German technician Paul Nipkow back in 1884. A Nipkow disk made of an opaque material with a number of holes of equal diameter, arranged in a spiral in one turn from the center of the disk at an equal angular distance from each other, was used both for scanning the image and for its formation on the receiving apparatus.
Nipkow disc device
The lens focused the image of the subject on the surface of the rotating disk. Light, passing through the holes, fell on the photocell, due to which the image was converted into an electrical signal. Since the holes were arranged in a spiral, each of them actually performed a line-by-line scan of a certain area of ββthe image focused by the lens. Exactly the same disk was present in the playback device, but behind it was a powerful electric lamp that perceived fluctuations in light, and in front of it was a magnifying lens or lens system that projected an image onto a screen.
The principle of operation of mechanical television systems
Baird's apparatus used a Nipkow disk with 30 holes (as a result, the resulting image had a scan of only 30 vertical lines) and could scan objects at a frequency of 5 frames per second. The first successful experiment in transmitting a black-and-white image took place on October 2, 1925: then the engineer managed for the first time to broadcast from one device to another halftone image of a ventriloquist doll.
During the experiment, a courier called at the door, who was supposed to deliver important correspondence. Encouraged by the success, Baird grabbed the discouraged young man by the arm and led him into his laboratory: he was eager to evaluate how his offspring would cope with the transmission of the image of a human face. So 20-year-old William Edward Tainton, being at the right time in the right place, went down in history as the first person to "get on TV."
In 1927 Baird conducted the first television broadcast between London and Glasgow (over a distance of 705 km) over telephone wires. And in 1928, the Baird Television Development Company Ltd, founded by an engineer, successfully completed the world's first transatlantic transmission of a television signal between London and Hartsdale, New York. Demonstration of the capabilities of Baird's 30-band system turned out to be the best advertisement: already in 1929, the BBC adopted it and successfully used it for the next 6 years, until it was supplanted by more advanced equipment based on cathode ray tubes.
Iconoscope - a harbinger of a new era
The world owes the appearance of the cathode-ray tube to our former compatriot Vladimir Kozmich Zworykin. During the Civil War, the engineer took the side of the white movement and fled through Yekaterinburg to Omsk, where he was engaged in the equipment of radio stations. In 1919, Zworykin went on a business trip to New York. Just at that time, the Omsk operation took place (November 1919), the result of which was the capture of the city by the Red Army almost without a fight. Since the engineer had nowhere else to return, he remained in forced emigration, becoming an employee of Westinghouse Electric (currently CBS Corporation), which was already one of the leading electrical corporations in the United States, where he was simultaneously engaged in research in the field of image transmission over a distance.
Vladimir Kozmich Zworykin, creator of the iconoscope
By 1923, the engineer managed to create the first television device, which was based on a transmitting electron tube with a mosaic photocathode. However, the new bosses did not take the work of the scientist seriously, so for a long time Zvorykin had to conduct research on his own, in conditions of extremely limited resources. The opportunity to return to full-fledged research activities was presented to Zworykin only in 1928, when the scientist met another emigrant from Russia, David Sarnov, who at that time was vice president of the Radio Corporation of America (RCA). Finding the inventor's ideas very promising, Sarnov appointed Zworykin the head of the RCA electronics laboratory, and things got off the ground.
In 1929, Vladimir Kozmich presented a working prototype of a high-vacuum television tube (kinescope), and in 1931 he completed work on a receiving device, which he called "iconoscope" (from the Greek eikon - "image" and skopeo - "to look"). The iconoscope was a vacuum glass flask, inside of which a light-sensitive target and an electron gun located at an angle to it were fixed.
Schematic diagram of the iconoscope
A light-sensitive target 6 Γ 19 cm in size was represented by a thin plate of insulator (mica), on one side of which were deposited microscopic (several tens of microns each) silver drops in the amount of about 1 pieces coated with cesium, and on the other side - solid silver coating, from the surface of which the output signal was taken. When the target was illuminated, under the action of the photoelectric effect, silver droplets acquired a positive charge, the value of which depended on the illumination level.
The original iconoscope on display at the Czech National Museum of Technology
The iconoscope formed the basis of the first electronic television systems. Its appearance made it possible to significantly improve the quality of the transmitted picture by multiplying the number of elements in the television image: from 300 Γ 400 dots in the first models to 1000 Γ 1000 dots in more advanced ones. Although the device was not without certain shortcomings, which include low sensitivity (for full-fledged shooting, illumination of at least 10 thousand lux was required) and keystone distortion caused by the mismatch of the optical axis with the axis of the beam tube, Zworykin's invention became an important milestone in the history of video surveillance, in largely determining the further vector of development of the industry.
On the way from analogue to digital
As often happens, military conflicts contribute to the development of certain technologies, and video surveillance in this case is no exception. During the Second World War, the Third Reich began the active development of long-range ballistic missiles. However, the first prototypes of the famous "retaliation weapon" V-2 were not very reliable: the rockets often exploded at the start or fell shortly after takeoff. Since advanced telemetry systems did not yet exist in principle, the only way to determine the cause of failures was to visually observe the launch process, but this was extremely risky.
Preparations for the launch of the V-2 ballistic missile at the PeenemΓΌnde test site
To make it easier for the developers of missile weapons and not endanger their lives, the German electrical engineer Walter Bruch designed the so-called CCTV system (Closed Circuit Television). The necessary equipment was installed at the PeenemΓΌnde training ground. The creation of a German electrical engineer allowed scientists to observe the progress of the tests from a safe distance of 2,5 kilometers, without fear for their own lives.
With all its advantages, the Bruch video surveillance system had a very significant drawback: it did not have a video recording device, which means that the operator could not leave his workplace even for a second. The seriousness of this problem allows us to evaluate the study conducted by IMS Research in our time. According to its results, a physically healthy, well-rested person will lose sight of up to 45% of important events after just 12 minutes of observation, and after 22 minutes this figure will reach 95%. And if in the field of testing missile weapons this fact did not play a special role, since scientists did not need to sit in front of the screens for several hours in a row, then in relation to security systems, the lack of the possibility of video recording significantly affected their effectiveness.
This continued until 1956, when the first Ampex VR 1000 video recorder, again created by our former compatriot Alexander Matveyevich Poniatov, saw the light of day. Like Zworykin, the scientist took the side of the White Army, after the defeat of which he first emigrated to China, where he worked for 7 years in one of the electric power companies of Shanghai, then lived in France for some time, after which in the late 1920s he moved to permanent residence in United States and received American citizenship in 1932.
Alexander Matveevich Ponyatov and the prototype of the world's first video recorder Ampex VR 1000
Over the next 12 years, Ponyatov worked for companies such as General Electric, Pacific Gas and Electric and Dalmo-Victor Westinghouse, but in 1944 he decided to start his own business and registered Ampex Electric and Manufacturing Company. At first, Ampex specialized in the production of high-precision drives for radar systems, but after the war, the company's activities were reoriented to a more promising direction - the production of magnetic sound recording devices. Between 1947 and 1953, Poniatov's company produced several very successful models of tape recorders that were used in the field of professional journalism.
In 1951, Ponyatov and his chief technical advisers Charles Ginzburg, Veiter Celsted and Miron Stolyarov decided to go further and develop a video recorder. In the same year, they created a prototype Ampex VR 1000B, using the principle of cross-line recording of information by rotating magnetic heads. This design made it possible to provide the necessary level of performance for recording a television signal with a frequency of several megahertz.
Scheme of cross-line recording of a video signal
The first commercial model of the Apex VR 1000 series was released after 5 years. At the time of release, the device was sold for 50 thousand dollars, which at that time was a huge amount. For comparison: the Chevy Corvette, released in the same year, was offered for only $ 3000, and this car belonged, for a minute, to the category of sports cars.
It was the high cost of equipment that for a long time had a deterrent effect on the development of video surveillance. To illustrate this fact, it is enough to say that in preparation for the visit of the Thai royal family to London, the police installed only 2 video cameras on Trafalgar Square (and this was to ensure the safety of the first persons of the state), and at the end of all events, the security system was dismantled.
Queen Elizabeth II and Prince Philip, Duke of Edinburgh welcome King Bhumibol of Thailand and Queen Sirikit
The advent of zoom, pan, and turn by timer made it possible to optimize the cost of building security systems by reducing the number of devices needed to control the territory, but the implementation of such projects still required considerable financial investments. For example, the city's Olean, New York City video surveillance system, commissioned in 1968, cost the city $1,4 million and took 2 years to deploy, despite the fact that the entire the infrastructure was represented by only 8 video cameras. And of course, there was no talk of any round-the-clock recording at that time: the VCR was turned on only at the command of the operator, because both the film and the equipment itself were too expensive, and their operation in 24/7 mode was out of the question.
Everything changed with the spread of the VHS standard, the appearance of which we owe to the Japanese engineer Shizuo Takano, who worked at JVC.
Shizuo Takano, creator of the VHS format
The format assumed the use of azimuth recording, in which two video heads are involved at once. Each of them recorded one television field and had working gaps deviated from the perpendicular direction by the same angle of 6Β° in opposite directions, which made it possible to reduce crosstalk between adjacent video tracks and significantly reduce the gap between them, increasing the recording density. The video heads were located on a drum with a diameter of 62 mm, rotating at a frequency of 1500 rpm. In addition to the slanted video tracks, two audio tracks separated by a guard gap were recorded along the upper edge of the magnetic tape. A control track was recorded along the lower edge of the tape, containing frame sync pulses.
When using the VHS format, a composite video signal was recorded on the cassette, which made it possible to get by with a single communication channel and significantly simplify switching between the receiving and transmitting devices. In addition, unlike the Betamax and U-matic formats popular in those years, which used a U-shaped magnetic tape refilling mechanism with a turntable, which was typical for all previous cassette systems, the VHS format was based on a new principle of the so-called M - gas stations.
Scheme of M-refilling magnetic tape in a VHS cassette
The removal and loading of the magnetic tape was carried out using two guide forks, each of which consisted of a vertical roller and an inclined cylindrical stand, which determined the exact angle of the tape entering the drum of the rotating heads, which ensured the inclination of the video track to the base edge. The angles of entry and exit of the tape from the drum were equal to the angle of inclination of the plane of rotation of the drum to the base of the mechanism, due to which both rolls of the cassette were in the same plane.
The M-loading mechanism proved to be more reliable and helped to reduce the mechanical stress on the film. The absence of a turntable simplified the manufacture of both the cassettes themselves and VCRs, which had a positive effect on their cost. Largely due to this, VHS won a landslide victory in the βformat warβ, making video surveillance truly accessible.
Video cameras also did not stand still: devices with a cathode ray tube were replaced by models made on the basis of CCD matrices. The world owes the appearance of the latter to Willard Boyle and George Smith, who worked at AT & T Bell Labs on semiconductor data storage devices. In the course of their research, physicists discovered that the integrated circuits they created are subject to the photoelectric effect. As early as 1970, Boyle and Smith introduced the first linear photodetectors (CCD arrays).
In 1973, Fairchild began mass production of CCDs with a resolution of 100 Γ 100 pixels, and in 1975, Steve Sasson from Kodak created the first digital camera based on such a matrix. However, it was completely unusable, since the image formation process took 23 seconds, and its subsequent recording on an 8 mm cassette lasted one and a half times longer. In addition, 16 nickel-cadmium batteries were used as a power source for the camera, and all this stuff weighed 3,6 kg.
Steve Sasson and Kodak's first digital camera compared to modern day cameras
The main contribution to the development of the digital camera market was made by Sony Corporation and personally by Kazuo Iwama, who headed the Sony Corporation of America in those years. It was he who insisted on investing huge amounts of money in the development of their own CCD chips, thanks to which, already in 1980, the company introduced the first color CCD video camera, the XC-1. After Kazuo's death in 1982, a tombstone with a CCD embedded in it was installed on his grave.
Kazuo Iwama, President of Sony Corporation of America in the 70s
Well, September 1996 was marked by an event that can be compared in importance with the invention of the iconoscope. It was then that the Swedish company Axis Communications introduced the world's first "digital camera with web server functions" NetEye 200.
Axis Neteye 200 is the world's first IP camera
Even at the time of release, NetEye 200 could hardly be called a video camera in the usual sense of the word. The device was literally inferior to its brothers on all fronts: its performance ranged from 1 frame per second in CIF format (352 Γ 288, or 0,1 MP) to 1 frame per 17 seconds in 4CIF (704 Γ 576, 0,4 MP), moreover, the record was not even saved in a separate file, but as a sequence of JPEG images. However, the main feature of the brainchild of Axis was not at all the shooting speed and not the clarity of the picture, but the presence of its own ETRAX RISC processor and a built-in 10Base-T Ethernet port, which made it possible to connect the camera directly to a router or PC network card as a normal network device and manage it using the supplied Java applications. It was this know-how that forced many manufacturers of video surveillance systems to radically reconsider their views and for many years determined the general vector of the industry's development.
More features - more costs
Despite the rapid development of technology, even after so many years, the financial side of the issue remains one of the key factors in the design of video surveillance systems. Although the scientific and technical progress has contributed to a significant reduction in the cost of equipment, thanks to which today it is possible to assemble a system similar to the one installed in Olean in the late 60s for literally a couple of hundred dollars and a couple of hours of real time, such an infrastructure is no longer able to satisfy the many times increased needs of modern business .
This is largely due to a shift in priorities. If earlier video surveillance was used only to ensure security in a protected area, today the main driver of the industry development (according to Transparency Market Research) is retail, which such systems help to solve various marketing tasks. A typical scenario is to determine the conversion rate based on information about the number of visitors and the number of customers who passed through the checkout counters. If we add a face recognition system here, integrating it with the current loyalty program, we will get the opportunity to study the behavior of buyers with reference to socio-demographic factors for the subsequent formation of personalized offers (individual discounts, bundles at a bargain price, etc.).
The problem is that the implementation of such a video analytics system is fraught with significant capital and operating costs. The stumbling block here is face recognition of buyers. It is one thing to scan a full-face face at the checkout with contactless payment, and quite another in the flow (on the trading floor), at different angles and in different lighting conditions. Here, only real-time XNUMXD face modeling using stereo cameras and machine learning algorithms can demonstrate sufficient efficiency, which will inevitably increase the load on the entire infrastructure.
With this in mind, Western Digital has developed the concept of Core to Edge storage for Surveillance, offering customers a comprehensive set of modern camera-to-server video recording solutions. The combination of advanced technologies, reliability, capacity and performance allows you to build a harmonious ecosystem that can solve almost any task and optimize the cost of its deployment and maintenance.
The flagship line of our company is a family of specialized hard drives for video surveillance systems WD Purple with a capacity of 1 to 18 terabytes.
Purpose-built for XNUMX/XNUMX HD video surveillance applications, the Purple Series incorporates Western Digital's latest hard drive technology.
- Platform HelioSeal
The older models of the WD Purple line with capacities from 8 to 18 TB are based on the HelioSeal platform. The housings of these drives are absolutely hermetic, and the HDA is filled not with air, but with rarefied helium. The reduction of the resistance force of the gaseous medium and the turbulence indicators made it possible to reduce the thickness of the magnetic plates, as well as to achieve a higher recording density by the CMR method due to an increase in the positioning accuracy of the head (using Advanced Format Technology). As a result, switching to WD Purple provides up to a 75% increase in capacity in the same racks, without the need to scale the infrastructure. In addition, helium drives are 58% more energy efficient compared to conventional HDDs by reducing the power required to spin up and rotate the spindle. Additional savings come from reduced air-conditioning costs, with WD Purple cooler by an average of 5Β°C under the same load.
- AllFrame AI technology
The slightest interruption during recording can lead to the loss of critical video data, making subsequent analysis of the information received impossible. To prevent this, support for the optional Streaming Feature Set section of the ATA protocol was introduced into the firmware of the purple series drives. Among its capabilities, it is necessary to highlight the optimization of cache usage depending on the number of processed video streams and the control of the priority of execution of read / write commands, which makes it possible to minimize the likelihood of frame drops and the appearance of image artifacts. In turn, the innovative set of AllFrame AI algorithms makes it possible to use hard drives in systems that process a significant number of isochronous streams: WD Purple drives support simultaneous operation with 64 high-definition cameras and are optimized for high-load video analytics and Deep Learning systems.
- Time Limited Error Recovery Technology
One of the common problems when working with highly loaded servers is the spontaneous collapse of the RAID array, caused by exceeding the allowable error recovery time. The Time Limited Error Recovery option helps to avoid turning off the HDD if the timeout goes beyond 7 seconds: to prevent this from happening, the drive will give the RAID controller an appropriate signal, after which the correction procedure will be postponed until the system is idle.
- Monitoring system Western Digital Device Analytics
The key challenges that must be addressed when designing video surveillance systems are increasing uptime and reducing downtime due to failure. Using the innovative Western Digital Device Analytics (WDDA) software package, the administrator has access to a variety of parametric, operational and diagnostic data on the status of drives, which allows you to quickly identify any problems in the operation of the video surveillance system, plan maintenance in advance, and promptly identify hard drives that need to be replaced . All of the above helps to significantly increase the fault tolerance of the security infrastructure and minimize the likelihood of loss of critical data.
Especially for modern digital cameras, Western Digital has developed a line of highly reliable WD Purple memory cards. The extended rewriting resource and resistance to negative environmental influences make it possible to use these cards for equipping both internal and external video surveillance cameras, as well as for operation as part of autonomous security systems in which microSD cards play the role of the main data storage devices.
Currently, the WD Purple memory card series includes two product lines: WD Purple QD102 and WD Purple SC QD312 Extreme Endurance. The first included four modifications of flash drives ranging from 32 to 256 GB. Compared to consumer solutions, WD Purple has been specially adapted to modern digital video surveillance systems through the introduction of a number of important improvements:
- moisture resistance (the product can withstand immersion to a depth of 1 meter in fresh or salt water) and an extended operating temperature range (from -25 Β°C to +85 Β°C) make it possible to use WD Purple cards equally effectively for equipping both indoor and outdoor devices video recording regardless of weather and climatic conditions;
- protection against static magnetic fields with an induction of up to 5000 gauss and resistance to strong vibration and shock up to 500 g completely exclude the possibility of losing critical data even if the video camera is damaged;
- Guaranteed resource of 1000 programming/erasing cycles makes it possible to multiply the service life of memory cards even in the round-the-clock recording mode and, thus, significantly reduce the overhead costs for maintaining the security system;
- the remote monitoring function helps to quickly monitor the status of each card and more efficiently plan service work, which means further increasing the reliability of the security infrastructure;
- Compliance with UHS Speed ββClass 3 and Video Speed ββClass 30 (for cards 128 GB and above) makes WD Purple cards suitable for use in high-definition cameras, including panoramic models.
The WD Purple SC QD312 Extreme Endurance line includes three models: 64, 128 and 256 gigabytes. Unlike the WD Purple QD102, these memory cards are capable of withstanding a much higher load: their working life is 3000 P / E cycles, which makes these flash drives ideal for use in highly protected facilities where recording is done 24/7.
Source: habr.com