- Burglar and Fire Alarm Systems
- Digital Video Recorders
- Camera Web Servers
- Monitored & Non-Monitored Systems
- Access Control
- Point Of Sale Networks
- Power, Network and Phone Wiring
- Closed Circuit TV
- Cable TV Networks
- Fibre Optic Networks
- Alarm Systems
What You Should Know
Consider what the large companies that require a dependable economical system purchase. Honeywell Ademco alarm panels and accessories are one of the two most used systems in the large commercial accounts that we service.
Devices, such as motion detectors, door and window contacts, glass break detectors, etc., are the eyes and ears of the alarm panel. They can be connected to the alarm panel in two different ways. The first and original way is though wiring, but they can also be wireless. Using concealed wiring will cost more at the time of installation, but the devices themselves are less expensive, require less maintenance, and are not susceptible to interference. Installing concealed wire in an existing structure requires “fishing” the wires inside of walls, floors and ceilings. Normally, the wiring and devices are maintenance-free after the installation. Wireless devices require batteries. The average battery life of a wireless device can range from six months to three years, depending on the application. The more active the device is, the shorter the battery life. A motion detector in a high traffic area, or a glass break detector in a room with a loud stereo or TV, will shorten battery life. You can be shown how to replace your own batteries or you can pay for a service call to have someone replace them for you. The alarm panel or monitoring company will alert you to a low battery. A wireless device, because it is also a transmitter, is not only more expensive to purchase, but has a higher failure rate than a wired device. Replacement of a wireless device is also more expensive as it requires that the panel be re-programmed to accept the new device code. Some companies offer an “all-in-one” system that is a combination keypad, panel, dialer and siren. In the case of a break-in, the intruder only needs to rip the system off the wall to totally disable it. The systems that we install only have the keypad by the door. If the keypad is ripped from the wall the panel still alarms and connects to the monitoring company.
What You Should Know
The most commonly used cameras are the CCD or charged coupled devices. Cameras come in black and white and color. Black and white are less expensive and can be better for low light applications as less light is required to see an image through a black and white camera. Color cameras are easier to view over extended periods and are essential where data on color is important.
A critical consideration when choosing a camera is its ability to operate in low light conditions. Cameras now regularly operate to 1.0 lux for color cameras and 0.1 lux for black and white cameras. Another important consideration is resolution, which is the ability of the camera to reproduce images with as many details as possible. Resolution is expressed in TV lines or TVL and may be 330 to 520 lines for color and 380 to 580 lines fro black and white. Also signal to noise ratio is important in low light conditions. Cameras can be visible or hidden.
Cameras can be mounted on moveable platforms and these are called Pan Tilt Cameras. These cameras can be used to view many different locations and usually have zoom lenses. A recent development of the Pan tilt Camera is the integrated speed dome. This is usually a pendant housing and allows a camera to cover many positions – usually with a number of pre-set positions, so that the camera can travel extremely quickly between the various subjects, refocusing as it does so.
To see properly, a CCTV camera requires a certain amount of light produced by natural or artificial illumination. B/W cameras work with any type of light sources, but color cameras need lights that contain all the colors in the visible spectrum for best color imaging.
The amount of light is defined by LUX (Lumens per Square Meter). One LUX is one candle light volume at one meter distance. Followings are some examples of natural lights expressed in LUX.
Natural LUX Examples
Full daylight: 10,000 LUX
Very dark day: 100 LUX
Twilight: 10 LUX
Deep twilight: 1 LUX
Full moon: 0.1 LUX
Quarter moon: 0.01LUX
There are three types of lenses for use in different light conditions: Fixed Aperture, Manual Iris, and Auto Iris. If the area you wish to observe experiences infrequent changes in light, use a manual iris lens, which can be adjusted for light only by hand. If the area the Security Camera will be observing experiences frequent changes in light, use an auto-iris lens. These lenses adjust to light changes automatically.
There are different focal lengths available for camera lenses. The focal length determines the viewable area that the camera will see. In the chart below, you can see that a focal length of 8mm at a distance of 50 feet will give an image that is 28.7ft wide by 21.3 ft high.
The lens can also be fixed focus or auto focus. A fixed focus lens will only give a sharp image at a set distance from the camera. Auto focus lenses normally only give a sharp image of the center of the viewed image. Because of this, if the target is moving, it may not focus on the part of the image that you are really interested in seeing.
A CCTV digital video recorder (or “DVR” for short) is essentially a computer that saves security video images to a hard drive. Most security cameras in use today capture an analog picture. The DVR converts the analog signal to digital and then compresses it. The newer IP cameras send the image to the DVR already in a digital format. Digital recorders also have built in multiplexing and usually record four, eight or sixteen cameras. Most DVR’s come with built-in motion detection and continuously monitor the picture from the cameras. As soon as there is movement they begin recording.
All DVRs are definitely not made equal. There are several factors that are critical to consider when purchasing a DVR, especially when comparing price. The most important factors to look at are the number of cameras supported, frames per second (fps), compression technology, hard drive space, network connection / remote viewing capability, motion detection, scheduling, and ability to save video and audio to a CD or flash drive. You should also look for easy and comprehensive search capabilities. The setup and user interface should be intuitive and easy to operate.
The amount of hard drive space is very important because it will limit how many days of recording you can store before the system has to start recording over the oldest video. Each DVR will have its storage capacity listed in the specifications. But this calculation is just a rough estimate as there are many factors that affect hard drive use. The most critical factor being the compression format used by the DVR. But also the type of cameras that are connected to the DVR make a difference (specifically the chip size and resolution) and also the features that are selected on the DVR. If you use the scheduling or motion detection features or tune down the frame rate it will extend the storage capacity of the unit. Even the field of view (what you are recording) will affect the storage capacity – the more complex the image, the more hard drive space it will take to capture the complexity.
The compression technology, the number of cameras, the size of the hard drive, whether or not motion-recording control is being used and the picture size and quality determine the length the recorder will record for. All DVRs have a specified maximum frame rate and the frame rate available per individual camera is determined by dividing the maximum frame rate by the number of cameras. Real Time by definition is 25 frames per second and this is the ideal (benchmark) frame rate for each camera. The frame rate for your installation will depend on the application – if you are monitoring cash or moving traffic the frame rate will need to be much higher than if you are monitoring movements in an office reception area. With the huge increases in storage space that new technology has delivered with larger hard drives the ability to store sufficient data images is no longer a problem.
2 Images Per Second = 1 Frame Per Second
Frames per Second: Frames per second means the amounts of full frames that a video camera captures and sends to a recording device or monitor per second. While most CCTV camera systems are easily able to capture 30 or more frames per second (30 fps is considered real time), the amount of video tape or digital storage would be enormous to record every moment of everyday. For most applications, speeds of 1 to 6 frames per second are more than enough to catch and record a perpetrator committing a crime.
DVRs have different resolution options and these simply determine the number of pixels in the picture. Higher numbers of pixels means higher clarity of the picture but this also uses more hard disk space.
After an incident has been recorded images can be time and date stamped and moved from the DVR to another storage device such as a USB memory stick or a CD.
Many DVRs are capable of sending an email or text message to a recipient when an event such as detection of movement occurs. Many can also be accessed through a computer network or even over the Internet (web server.)