F.A.Q.

What is CCTV?

CCTV stands for Closed-Circuit Tevevision. As the name implies, it is a system in which the circuit is closed and all the elements are directly connected. This is unlike broadcast television where any receiver that is correctly tuned can pick up the signal from the airwaves. A collection of cameras, tv/monitors, and optional recording devices directly connected together via cables or other direct means (such as wireless transmitters/receivers).

What are the Benefits of CCTV?

Closed Circuit Television is an indispensable element in a variety of security driven applications. In retail stores, experts report that inventory shrinkage typically originates at the point of sale. It is estimated that three times as much shrinkage occurs at the cash register than anywhere else in the store. Shrinkage drops dramatically when point-of-sale data is recorded with a complete picture of exactly what was purchased, by whom, and through which salesperson. Overt cameras on the sales floor act as a deterrence to external and internal theft by shoplifting. In major business complexes, management can use Closed Circuit Television to supervise parking areas, high risk storage facilities, and critical access points. Closed circuit television is commonplace in manufacturing environments where process monitoring is required.

Components of a Closed Circuit Television System vary by application and objective. Typically included are one or more black and white or color cameras, a monitor, and a time lapse video recorder. Use of multiple cameras usually requires a switching device. Systems may require environmental housings for outdoor use and automatic iris lenses to compensate for mechanisms and zoom capability to enhance results. High resolution cameras, monitors and recording devices improve the chances of identification. New transmission formats now allow managers and business owners to remotely monitor activities at designated facilities from virtually any point on the globe where telephone access is present. And new technology has led to the ability to capture all activity on a hard drive (HDD) for seem less video replay with out the problems associated with video tape play back. For more information on Closed Circuit Television, contact DHM Enterprise LLC. and lets see what we can do for you.

What is a DVR (Digital Video Recorder)?

A DVR is a feature-packed, state-of-the-art, PC based, digital video surveillance and recording system, utilizing the latest in video capture and storage technologies. With features like; remote viewing, remote backup and remote setup; integrated alarmed recording, or motion detection recording; enhanced M JPEG compression, and password protection, the DVR leaves very little else to be desired. DVR’s may be configured in multiples of up to 16 video channels per DVR, with ability to stack systems for an infinite quantity of video channels. The video storage capacity for each DVR is virtually unlimited.

How does the DVR differ from traditional Analog Video systems?

Analog tape, as in the case of a VCR, works by magnetically encoding a representation of a video signal on a long strip of metallic coated plastic. This strip of plastic moves past what is known as a head inside of the VCR. Heads are responsible for converting the magnetic energy into electricity for playback, and vice-versa for recording. Other components inside the VCR keep the tape moving past the heads at precisely the correct speed. It should be noted that practically every component in a VCR physically touches the tape, causing wear and tear on the tape itself.

While it can be argued that VHS cassette tapes reproduce images accurately, they are plagued by several other problems that reduce video quality. Tape suffers from "noise", dropouts (periodic loss in signal level), and image inconsistency (periodic changes in brightness and clarity due to the mechanics of the VCR or the stretching of the tape itself). Expensive, commercial grade VCRs attempt to get around many of these problems with special electronics and high quality mechanisms.

Analog tape is not an especially robust medium. Inexpensive consumer-grade VHS cassette tapes start to lose quality after they have been played even a few times. The most expensive VHS cassettes last only a few hundred plays and/or records before noticeable degradation occurs, providing the VCR is in proper working order.

In addition, the overall functionality of the standard DVR system, we are currently working on many exciting add-on modules for the DVR. Some of these include integration with access control systems, POS, standard alarm panel status reporting, and web-enabled components which facilitate the incorporation of live images from the DVR system into your web page.

Most important, however, is the fact that we are committed to continuously improving our product, based upon the suggestions and comments from our customers. As a result, our customers and end-users are getting the features that they need now. As the DVR product software continues to improve, enhancements are always available for download to our customers from this web site.

What is the difference between Digital Video verses DVR’s?

Understanding what digital video is first requires an understanding of its ancestor - broadcast television or analogue video. The invention of radio demonstrated that sound waves can be converted into electromagnetic waves and transmitted over great distances to radio receivers. Likewise, a television camera converts the color and brightness information of individual optical images into electrical signals to be transmitted through the air or recorded onto video tape. Similar to a movie, television signals are converted into frames of information and projected at a rate fast enough to fool the human eye into perceiving continuous motion. When viewed by an oscilloscope, the un-projected analogue signal looks like a brain wave scan - a continuous landscape of jagged hills and valleys, analogous to the ever-changing brightness and color information.

Contrary to popular opinion, digital video is not new. Digital Video Recorders (DVR’s), available to the consumer are relatively new. Companies have been using digital video for years in a number of industries, and for a variety of purposes. From medical imaging to process control, the ability to capture, store and analyze images digitally has become more commonplace. Only recently, with the advancement in new technologies, has digital video become an affordable option for more practical applications, such as surveillance. As the potential market has increased, prices have fallen, and in so doing opened up the possibilities of digital video to an entirely new audience.

In the early 1990s, a digital video system capable of capturing full-screen video images would have cost thousands of dollars. The biggest cost element was the compression hardware, needed to reduce the huge files that result from the conversion of an analog video signal into digital data, to a manageable size. Less powerful 'video capture' cards were available, capable of compressing quarter-screen images - 320 x 240 pixels - but even these were far too expensive for the average user. The consumer end of the market was limited to basic cards that could capture video, but which had no dedicated hardware compression features of their own. These low-cost cards relied on the host PC to handle the raw digital video files they produced, and the only way to keep file sizes manageable was to drastically reduce the image size.

With the arrival of the Pentium processor in 1993, even the most powerful PCs were limited to capturing images no more than 160 x 120 pixels. For graphics cards running at a resolution of 640 x 480, a 160 x 120 image filled just one-sixteenth of the screen. As a result these low-cost video capture cards were generally dismissed as little more than toys, incapable of performing any worthwhile real-world application.

The turning point for digital video systems came as processors finally exceeded 200MHz. At this speed, PCs could handle images up to 320 x 240 without the need for expensive compression hardware. The advent of the Pentium II and ever more processing power made video capture cards which offered less than full-screen capability virtually redundant and by the autumn of 1998 there were several specialized video capture devices on the market which provided full-screen video capture for under a thousand dollars.

It is a combination of high-tech hardware and innovative, cutting-edge software which enables digital video to be efficiently utilized in areas which were once reserved for VHS tapes and time-lapse VCRs.

DVR

Computer based video recorders, by contrast to the VHS VCR, deal with video information in digits, i.e. ones and zeros, to be precise. To store visual information digitally, the hills and valleys of the analogue video signal have to be translated into the digital equivalent - ones and zeros - by a sophisticated computer-on-a-chip, called an analogue-to-digital converter (ADC). The conversion process is known as sampling, or video capture. Since computers have the capability to deal with digital graphics information, no other special processing of this data is needed to display digital video on a computer monitor.

However, to view digital video on a traditional television set, the process has to be reversed. A digital-to-analogue converter (DAC) is required to decode the binary information back into the analog signal. Technically, a digital image is comprised of a series of bits, represented by 1s and 0s. The arrangement and pattern of the bits reveal the necessary and crucial information needed to "reconstruct" the image so that it may be viewed on a monitor or printed on a printer.

The viewable image is comprised of tiny pixels, or dots. If the image is a color image, each pixel appears in a specific color. In the case of a black and white image, each pixel is displayed with a certain "brightness" making some appear pale gray and others appear black. The actual number of pixels depends on the size and resolution of the image. Obviously, the larger the image size selected, the greater number of pixels.

In the DVR, digital video recording of images (frames) from a camera, are "captured" and stored to hard disk in binary form (as described above). Because the digital system is not mechanical like a VCR, such factors as frame speed and video quality are software adjustable. Most digital systems on the market today allow users to adjust these settings as they see fit. Most video capture devices employ some sort of compression scheme to compress the captured images so they occupy less space on the storage media.

Inversely, this means that the images must be decompressed before they can be viewed. In the digital video world, this dual functionality is encapsulated in a "CODEC"; short for compressor / de-compressor. A codec is any technology for compressing and decompressing data. Codec’s can be implemented in software, hardware, or a combination of both. Because compression and decompression are "processor-intensive" operations, the hardware-based codec is generally considered to be more efficient.