What is video surveillance?
In its simplest form surveillance is the supervision of behavior, activities, or other changing information, usually of people for the purpose of influencing, managing, directing, or protecting. Video surveillance allows individuals to observe from a distance by means of electronic equipment such as closed-circuit television (CCTV) cameras. These cameras are often connected to a recording device or IP network, and be watch remotely or locally.
During the last decade video surveillance prices have dropped dramatically due to technological advancements. Where corporations, businesses, and other large entities ruled the buying market, homeowners have quickly become a major portion of the video surveillance market.
Analog surveillance equipment can record straight to a video tape recorder -- which record analog signals as pictures. When recording to a tape, the tape must run at a very slow speed in order to operate continuously. The reason for the slow speed is most tapes have 3-hours of space but need to be run for 24-hours thus the frames are turned down to approximately 4 frames per second. Seconds are everything in the world of video surveillance. Within one second a person can walk between 3 and 5 feet thus the distance is divided into four parts or frames. Analog surveillance can be, at most times, very blurry and difficult to assess.
Analog signals, however, can be converted into a digital signal to allow the recording to be stored on a personal computer (PC) as digital recordings. In order to convert analog to digital the camera must be plugged directly into a video capture card in the computer to allow the card to covert the signal. Digital video recorders (DVR) offer another solution for those wanting to convert analog signals without plugging into a computer. DVRs function similarly to a computer with a capture card and video recording software. Most DVRs designed for surveillance purposes are embedded devices that require less maintenance and easy to setup.
Digital cameras do not require a video capture card because they use a signal that can be saved directly to a computer. Uncompressed digital recordings take up an enormous amount of space thus digital signals are compressed 5:1 and DVD quality can be achieved with additional compression. Most standard recordings are somewhat poor in quality because most of the image chips within the devices record at 320p. Luckily, technological advancements have made high-definition (HD) cameras a lot more affordable.
Unlike analog surveillance equipment, digital surveillance equipment records at 30 framers per second. Digital recording are far more clear and visually smooth than analog equipment.
Network video recorders
IP cameras or network video recorders are either analog or digital video cameras, plus an embedded video server with an IP address, capable of streaming video. Network video recorders can be used for very cheap surveillance solutions or even replace entire CCTV installations. Network cameras can have resolutions higher than CCTV analog cameras. Some of the potential advantages of IP cameras or network cameras include:
- Ability for two-way audio
- Flexibility: IP cameras can be moved anywhere on an IP network (including wireless)
- Encryption and authentication
- Remote accessibility
- Network video cameras can function on a wireless network
Indoor and outdoor cameras
While indoor and outdoor cameras are very similar in size, shape, and color; some of the differentiating elements between the two types of cameras include:
- Lighting conditions
- Lens quality and selection
- Video quality
- Weather durability
- Mounting capabilities
- Power sources
Like the human eye cameras must adjust to light conditions. Cameras use a lens component called the auto-iris to electronically control light intake. The auto-iris works similarly to human eye by allowing less light when bright and more light when dark. A manual-iris is not necessary for outdoor cameras but becomes necessary for fixed lighting conditions like a hallway or office.
Often times people make the mistake of pointing cameras toward the light source. Pointing a camera toward the light source is equivalent to staring at the sun. When installing your camera essay to point your camera parallel to the light source to allow the auto- or manual-iris function properly. Standar cameras, like the human eye, have limitations which relate to extreme darkness. Day/night cameras are best for those looking to surveil darkness. Cameras equipped with day/night technology have the capacity to pick up light "near" infrared light regions, a range that is not visible to the human eye. While day/night technology can pickup images in "near darkness" it cannot pickup images in total darkness.
Lens quality and selection
When selecting a camera lens here are a few things to consider:
- Iris: The iris on the lens determines how the camera adjusts to light. There are variety of iris types including: auto-iris, manual iris, and fixed iris. Each iris serves a different purpose for surveillance conditions.
- Focal length: The focal length of a camera determines what area will be surveyed in regards to width and depth. Focal length is especially importnat for surveillance areas where detail is important. Retail stores, for example, need the ability for facial recognition and therefore need different focal length capabilities than a outdoor park area. Most of the lens market is dominated by 2.8mm (wide-angle), 3.6mm, 4mm, 6mm, 8mm fixed lens, and 6~15 vari-focal lens.
- Lens quality: Lastly you should know that there are immense differences in lens quality. There are plastic lens and glass lens. There is high quality glass and low quality glass. There are metal bodied lens and plastic bodied lens. There are also precision mounts and less precise mounts. Remember, your camera may be great but if lens is low quality the images will suffer.
There are primarily three basic grades of product in terms of resolution and quality.
- Standard: Standard resolution for color cameras range anywhere from 330 TV lines to 380 TV lines.
- High Resolution: High resolution for color cameras range anywhere from 450 TV lines to 480 Tv lines.
- High Definition: High definition cameras or new standard cameras ranger anywhere from 520 TV lines to 550 TV lines.
The more lines of resolution in the picture, the higher the quality of the picture should appear. Some camera manufacturers unethically list their cameras to contain more lines of resolution than they really have, to gain more market share.
While indoor and outdoor cameras are similar in size, shape, and color they differ in weather durability. Not all outdoor cameras are built alike. Some cameras are built to withstand rain and moisture while other are built to withstand sand, dust, snow, frost, and humidity. Some cameras are equipped with heaters and blowers to counteract the elements. Make sure to research the camera and its specifications before purchasing.
Mounting locations and capabilities are extremely important when maximizing video security. When possible mount cameras out of physical reach from hand and objects. Often times vandals and thieves will throw or spray solutions onto cameras to block their vision. Camera domes are a great solution to prevent vandalism. In addition, cameras should be mounted in unobstructed locations parallel to light sources. As discussed above, placing a camera facing a light source is equivalent to staring at the sun.
Regardless of camera type or function each and every camera needs power. Here's a list of different camera power sources:
- A small power pack can be connected to the camera and plugged into a local wall outlet, typically within a 6' range. Typically this sort of power adapter is extremely inconvenient for surveillance purposes.
- Electrical wire can be run from each camera back to a central location and all the electrical wires are terminated in a power panel.
- Electrical wire can be run from each camera back to a central location and all the electrical wires can each be attached to individual transformers, which can be plugged into a power strip and then into the wall. This method is not recommended as it usually is not very neat.
- Lastly, there is a type of cable known as "Siamese" cable, which houses a cable for video and an electrical wire for power, all in one single jacket. This way you only have to run a single cable from the camera back to the central location where the DVR and power are to be terminated.