Posts Tagged ‘ hard disk drive’

Digital Security Cameras

Written By:
Friday, September 2nd, 2011

Almost all the security cameras these days are digital security cameras.  Compared to their old analog equivalents, they are lighter, more efficient, use less electricity, and just about anyone can install them.

Digital security cameras are a small-package of technological wonders from the lens to the video transmission type it uses.  In addition, digital security cameras get to “piggy back” on the personal computer industry; that is many times a device is advanced technologically for a computer; the digital security camera industry can reap the benefit of the advance as well.

In the following article, we’ll give you a brief overview of how a digital security camera actually works.  This should give you a better working knowledge so if you are considering a purchase you can make a wise one.

The digital security camera starts with a highly refined lens.   The lens has the responsibility of gathering the light reflected off objects in its field of vision and transferring the light images (with great detail), and small enough to be focused on a 1/4 inch square sensor chip.  The sensor chip is sensitive to light and emits tiny electrical impulse when exposed to light.

One of two different kinds of sensor chip is used in digital security cameras.  The Charged Coupled Device or CCD and the Complementary Metal Oxide Semiconductor or CMOS.   Although they go about it in different ways, the both produce the same end result; that is, electrical impulses that can be used to create a digital video image.

The digital security camera is actually nothing more than a very fast photographic camera.  It takes pictures at the rate of up to 30 pictures (called “frames) per second or denoted as 30 fps.  Playing back these pictures at the same speed they were taken gives the human brain the illusion that they are watching animation.  Actually, depending on many factors, rates as low as 15 fps can produce fluid animated video.

After each “picture” is taken that data is hurried along to an Integrated Circuit (IC) chip that is designed to correct for imbalances in many features of electronic video such as brightness, hue, color saturation, etc.  These specialized IC chips are called Digital Signal Processors or DSPs.  In addition up to this point the signals have actually been analog signals and it is here that they are converted into binary or digital form.

Once the cameras signals have been processed and digitized, they must be sent to the DVR for further action.  This is usually done via a video transmission cable, RG59 for example.

The DVR has many responsibilities including receiving the video transmission, saving it on a Hard Disk Drive or other non-volatile storage medium, and broad casting the signal to the Internet (if so desired) or a local monitor for live monitoring.

Don’t underestimate the power of the DVR and digital security cameras.  The DVR has a lot of simultaneous work that must be done.  Consider this; the digital security camera takes 30 pictures a second.  Let’s say for medium to high quality each picture taken ends up being about 1 MB in size.  Multiply that megabyte by 30 (the number taken in one second) now multiply that number by 60 (the number of seconds in a minute), and finally by 60, the number of minutes in one hour.   That means that an hour of security video imagery would be approximately 108,000 megabytes or 108 gigabytes!

To maintain quality but reduce the size of the video file, the DVR uses a CODEC utility which shrinks the size of the file but maintains as much quality as possible while doing this.   All of Security Camera King’s DVRs utilize the latest most efficient CODEC called H.264

So, as you can see there is a lot of work that goes on behind the scenes when using digital security cameras.  But even so, the versatility, price, application, functionality, and overall quality of the digital security camera is still much farther ahead that it’s older counterpart, the analog security camera.


Color Security System

Written By:
Friday, February 4th, 2011

Color Security SystemA digital video color security system is a video camera based protection and monitoring component system. Although a bear-bones system may only require two separate devices to operate, it normally consists of three or more. At a minimum a color security system requires at least one camera and a Digital Video Recorder or DVR. However, if you want to be able to watch what your system is recording, you will also want to use the third component, a color monitor.

The “work flow” of a color security system begins with, and is really based on, the digital video color security camera. A color security system may have only one camera, or it can consist of as many as sixteen when the system utilizes one DVR. The camera or cameras send their color video data to the DVR unit which contains an on-board computer processor designed specifically to do work with color video data and coordinate the color security system functions. Once the processor has interpreted the digital data from the camera, it compiles the data into a digital video file which can be viewed live if a monitor accompanies the system and/or saved for later use on the DVR hard disk drive.

The digital video camera in a color security system records digital images by converting light energy into electrical energy. It does this using one of two different sensors that create measurable electronic charges when light strikes their photosites. The sensors are known as Charged Coupled Devices or CCDs or Complimentary Metal Oxide Semiconductors or CMOSs.

These sensors have tremendously small diodes in an incredibly small amount of area. Most color security system cameras’ sensor chips are less than 1/2 inch square in size. The lens focuses the light image on this small area, which on a typical 1/2 inch CCD can contain 300,000 to 500,000 photosites. The sensors’ photosites are usually designated to detect red, green, or blue light. This configuration is often called a Bayer filter. When the data from all of the red, green, and blue sensing diodes or photosites is compiled it creates a high quality electronic color image.

The color security system further processes the electronic image by passing it through an on-board circuit chip called an analog-to-digital converter. This converts the electronic analog signals into binary or digital data that is then transmitted in a variety of ways, one of the most common being along an RG-59 coaxial video transmission cable. (Signals can also be sent wirelessly via radio waves).

The other end of the cable is connected to the DVR unit. The data from the color security system camera is still unrefined and it is the responsibility of the DVR unit with its accompanying Digital Signal Processor or DSP to add the finishing touches. It does this by using a utility, either in software form or contained in an on-board microchip, that reduces the size of the otherwise incredibly large digital video file without sacrificing a significant amount of quality.

Digital video, like cinematography, actually consists of several photographs (digital-based in this case) that are taken in a very short period of time. The human eye and brain are slow enough to fool into thinking they are seeing fluid, motion video if the photographs pass by quick enough. The number of photographs taken in one second is usually called the “frame rate” and is designated as “frames per second” or fps and is typically around 29 fps.

Consider the file size of a typical high quality digital camera. Now multiply that size times 29 and you have the size of the digital file for one second. Multiply that times 60 seconds, and again times 60 minutes, and the result for one hour of video at that rate is 104,400 times the size of one digital photograph. You can appreciate how large the file size can be.

Every color security system uses a form of the utility mentioned above. One of the most recent and efficient COmpression/DECompression or CODEC utilities is the H.264. Using the CODEC makes the files much easier to handle and increases maximum storage capacity of the DVR.

Security Camera King features several different color security systems including our Elite Mini, Elite, and Ultimate DVRs. We’ve designed our color security systems to give you the freedom to change components to make the system fit your specific needs. Contact one of our security experts today for more information.


Security Flood Light DVR Camera

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