Integrated Surveillance Systems

Integrated Surveillance Systems - Equipment Page

Security cameras

 

There are many technical terms and specifications that dealers will refer to when discussing security cameras as part of a CCTV system.

The basic technology behind most security cameras is the Charge Coupled Device (CCD). CCDs convert the images that come through the camera's lens into electronic impulses. CCDs provide a good combination of low price and quality picture for security applications.

Camera formats are measured in inches: most cameras fall between 1/4" and 1". This refers to the usable image size created inside the camera. For most security systems, a small size is fine - 1/4" or 1/3" cameras dominate CCTV sales. Larger formats do not necessarily result in better images, but can be advantageous in dimly lit situations since they are able to gather more light.

Color vs. black and white
Since prices have dropped significantly, many businesses today opt for color cameras over their black and white models. For security and evidence purposes, color cameras are better--sending security guards after "the man in the blue coat," for example, is much more difficult when you can not tell what color the coat is.
While black and white cameras can operate better than color cameras in extremely low light situations, most small to medium sized businesses use CCTV in well-lit indoor environments. In addition, many high-quality color cameras today can switch to black and white mode when necessary. Some vendors do not even sell black and white cameras any more.

Resolution
Resolution refers to how detailed a picture the camera can see. The measurement to look for is horizontal TV lines (TVL). A normal CCTV picture is around 350 to 400 TVL, with high resolution getting up to 480 or 500. Upgrading a camera's resolution can cost as little as $50.
You need to make sure your entire system is capable of supporting that resolution. If your VCR records 350 lines and your monitor displays 400, the money you spent to upgrade to a camera with 500 lines is completely wasted. In the end, the small cost to upgrade your camera may be multiplied by the costs to upgrade other equipment.

Note: do not be impressed by pixel measurements in the hundreds of thousands. TVL is a more consistent measurement.

Other specs Signal to noise ratio (s/n) indicates how much "signal," or actual picture information, the camera transmits, as opposed to "noise," which comes across as static. A s/n ratio of 40db indicates that the signal is 100 times the noise, which results in an acceptable picture with some fine grain or snow. 30db results in a poor picture, and 60db produces an excellent picture with no static visible. Keep in mind that noise can be introduced by other components in addition to the camera.
Sensitivity to light is measured in lux. A sensitivity of 2 lux means the camera can see fairly well by the light of a 40W fluorescent bulb; 0.5 lux cameras can make out images outside on a dim night. Your needs will depend on the lighting in the area being filmed, but lux ratings should not be the most important aspect of your camera decision.

 

Surveillance Camera Peripherals

Along with your CCTV camera, you need several peripherals to get your video surveillance system working.

Lenses
As with regular cameras, the lens on a security camera determines how wide an image is created and how much light is let in. Lenses are generally sold separately from cameras.
The lenses you purchase should match the format of your camera: 1/4" lenses work best with 1/4" cameras. It is possible to use a larger format lens than the camera calls for, but it is not recommended.

You also need to decide what type of lens you need. Fixed focal length lenses offer only one set field of view and are the least costly. To change the resulting image, you need to switch lenses. Variable focal length lenses and zoom lenses offer greater flexibility, allowing you to adjust your image's field of view. Motorized zoom lenses, the most costly type available, give you the ability to control your cameras remotely. If you want to zoom out for general surveillance and in for detail when you spot suspicious activity, motorized zooms are the way to go.

If you will be using the CCTV camera outdoors, look for a lens with an automatic iris. As in the human eye, the iris of a lens is what controls the amount of light coming in to the camera. Automatic irises can significantly improve performance for outdoor cameras, where light levels vary considerably. However, you can save money and use a manual iris lens when the scene illumination never changes, for example in an illuminated store or office.

Pan, Tilt, Zoom
For advanced security applications, you may want a pan, tilt, zoom (PTZ) camera. With the right equipment, a camera operator can pan (scan left and right), tilt (look up and down), and zoom in and out. The significant catch is the cost: PTZ systems are considerably more expensive than fixed cameras.

Housings
Cameras may need to be protected from potential vandalism or from the elements. Housings can range from simple coverings, to impact-resistant protection, to outdoor housings that include heaters and blowers for cooling. A more specialized type of housing is the dome: tinted Plexiglas hemispheres that prevent subjects from seeing which direction a camera is pointing. Choose the right housing based on the placement of the camera and its expected usage.

 

Surveillance camera monitors

Selecting a monitor for your CCTV system is a relatively minor decision, but there are a couple of important points to keep in mind.

First, make sure to purchase a monitor specially to handle the type of use it will receive. Televisions are not good monitors, since TVs are built to be on for a few hours per day, not the 8 to 24 hours per day they will endure. In some cases, computer monitors do make acceptable substitutes. Flat-panel LCD screens make great CCTV monitors for larger systems because they take up little space, have excellent resolution, and generate less heat than regular monitors.

As discussed earlier, make sure your monitor resolution matches your cameras. Buy a monitor with lower resolution and your camera's capabilities will not come through; buy one with higher resolution and you are throwing money away. And of course, make sure you buy color monitors if you opt for color cameras.

Also consider the size: a 9" monitor may be sufficient if the operator is sitting directly in front of it, but a 15" monitor is the smallest you should choose if you plan to combine images from multiple cameras onto one monitor. Merging multiple images onto one screen can be an effective way to save space, and appropriate if there is a dedicated employee who has the ability to zoom in on suspicious activity.

 

Security system recorders

Recording is essential to the effectiveness of any security system. Without recording, you need to have an employee watching a monitor at all times - hardly a cost-effective solution. And even if you spot suspicious activity, without a recording, you have nothing to use in court.

Almost all CCTV systems include some sort of recorder to store the images the cameras capture. Only a few years ago, the universal solution was the familiar VCR. However, the introduction of digital video recorders (DVRs), which record onto hard drives instead of tape, has dramatically changed the situation.

DVRs offer so many advantages over VCRs that they have rapidly taken over as the CCTV recording solution of choice:

- Ease of locating events - Instead of fast-forwarding through hours of tape, DVRs can instantly retrieve images from any specific time or date, or automatically skip to the point on a recording when something changed.
- Storage quality - Like all tapes, video cassettes start deteriorating almost immediately once you record on them - and the problem gets worse every time you reuse them. DVR recordings have no degradation at all since they are stored onto a hard drive.
- Multitasking - While analog VCRs can either record or play, most DVRs can do both at the same time, letting you review images while still recording.
- Smart monitoring - The DVR can be set to take one picture per second or less - just enough to create a running record. However when it detects motion, it can automatically bump the recording speed up to full (30 frames per second), getting every detail of the unauthorized activity.
For businesses that do not want to constantly change tapes, DVRs are definitely the way to go. While security VCRs usually offer a time-lapse mode that lets them for long periods of time, the resulting images are not a good record of events - they record only one snapshot every eight seconds. To get higher quality, you need to change tapes every day or more often. DVRs, on the other hand, can record for weeks or even months.

DVRs are more considerably more expensive than VCRs, which is their only major drawback. However, the DVR prices have fallen considerably over the last year and will continue to do so. Already, low-end DVRs and high-end VCRs are in similar price ranges, and most manufacturers have stopped introducing new VCR models. Despite the increased cost, we recommend CCTV system buyers purchase a DVR whenever possible.

 

Choosing a DVR
As part of your CCTV shopping preparations, decide how much quality you need out of your recorder. There is no magic number or spec here: you need to decide how "good" the recorded picture needs to be, either for your own use later or possibly to use in court. Once you decide this, you will be able to look at samples on the DVRs you are evaluating and see if they meet your standard. Vendors may be eager to throw compression settings, pixel counts, and other statistics at you - but those numbers are irrelevant if the picture itself does not offer the detail you need for legal or investigatory purposes.
The size of the hard drive will dictate how much you can record. On the low end, an 80-gigabyte (GB) hard drive will store about five to eight days of full-motion video from one camera. Most of the time you will not be recording full motion, so this is much more than it might seem. For most businesses, spending a little extra to get 120 or 240 GB is a worthwhile investment. Units expand up to 1.2 terabytes (1,200 GB), which can store many cameras' worth of data for long periods of time.

Replaceable hard drives are a cheap way to boost storage capacity. With some DVRs, you can buy additional hard drives for as little as $150 and swap them in and out as you need. This gives you the advantage of being able to store your data separately from the main security system.

You will also need to consider how many cameras you want to connect to the DVR. Keep your future expansion needs in mind - buying a higher-grade model to get more inputs and more storage space can save you considerable money in the future. The DVR will also function as a multiplexer, putting up to 16 cameras on one display and allowing operators to call up any one image for closer inspection.

Also, if you ever have to use your security images - in court or in other ways - you will need to be able to export the video. This is an important consideration: some systems let you create industry-standard .avi files, which can be played on any PC, and burn them to CD. Others only allow you to export proprietary formats that can only played on the same brand player. Most DVRs do offer the option to connect a standard VCR - this allows you to simply tape the digital recording onto a standard VHS cassette.

Wireless In most cases, wireless connections are not recommended for video surveillance systems. While wireless technology has taken off in recent years, it simply has not reached the level of reliability that CCTV users demand. The frequencies they use are subject to interference from cordless telephones, air conditioning, fluorescent lighting, and almost anything with an electric motor. Users will have to expect interference, usually resulting in a snowy picture. In addition, cameras need electrical power - so you will have to run one wire to the camera even if the video connection is wireless.
There are situations where wireless is the way to go: connecting across a public street, for example, where digging a trench is not a practical solution. Wireless systems are also better suited for rural areas, where there are fewer potential sources of interference. In these cases, wireless transmitters can make expensive or potentially impossible installations feasible.

 

Content Source: Experience & Yahoo