Network cameras
There is a wide range of network cameras to meet a variety of requirements. This
chapter describes what a network camera is and explains the different camera types.
Information is also provided about day and night, and megapixel network cameras.
A camera selection guide is included at the end of the chapter. For more on camera
elements.
What is a network camera?
A network camera, often also called an IP camera, can be described as a camera and computer
combined in one unit. The main components of a network camera include a lens, an image
sensor, one or several processors, and memory. The processors are used for image processing,
compression, video analysis and networking functionalities. The memory is used for storing the
network camera’s firmware (computer program) and for local recording of video sequences.
Like a computer, the network camera has its own IP address, is connected directly to a network
and can be placed wherever there is a network connection. This differs from a web camera,
which can only operate when it is connected to a personal computer (PC) via the USB or IEEE
1394 port, and to use it, software must be installed on the PC. A network camera provides web
server, FTP (File Transfer Protocol), and e-mail functionalities, and includes many other IP network
and security protocols.
NETWORK CAMERAS
Network camera PoE switch
Computer with video
management software
LAN LAN/Internet
A network camera can be configured to send video over an IP network for live viewing and/or
recording either continuously, at scheduled times, on an event or on request from authorized
users. Captured images can be streamed as Motion JPEG, MPEG-4 or H.264 video using various
networking protocols, or uploaded as individual JPEG images using FTP, e-mail or HTTP (Hypertext
Transfer Protocol). For more on video compression formats and networking protocols.
In addition to capturing video, Network cameras provide event management and intelligent
video functionalities such as video motion detection, audio detection, active tampering alarm
and auto-tracking. Most network cameras also offer input/output (I/O) ports that enable
connections to external devices such as sensors and relays. Other features may include audio
capabilities and built-in support for Power over Ethernet (PoE). Network cameras also
support advanced security and network management features.
Types of network cameras
Network cameras can be classified in terms of whether they are designed for indoor use only or
for indoor and outdoor use. Outdoor network cameras often have an auto iris lens to regulate
the amount of light the image sensor is exposed to. An outdoor camera will also require an
external, protective housing unless the camera design already incorporates a protective enclosure.
Housings are also available for indoor cameras that require protection from harsh environments
such as dust and humidity, and from vandalism or tampering. In some camera designs,
vandal and tamper-proof features are already built-in and no external housing is required. For
more on camera protection and housings.
Network cameras, whether for indoor or outdoor use, can be further categorized into fixed, fixed
dome, PTZ, and PTZ dome network cameras.
PTZ dome network cameras
PTZ dome network cameras can cover a wide area by enabling greater flexibility in pan, tilt and
zoom functions. They enable a 360-degree, continuous pan, and a tilt of usually 180 degrees.
PTZ dome cameras are ideal for use in discreet installations due to their design, mounting
(particularly in drop-ceiling mounts), and difficulty in seeing the camera’s viewing angle (dome
coverings can be clear or smoked).
A PTZ dome network camera also provides mechanical robustness for continuous operation in
guard tour mode, whereby the camera automatically moves from one preset position to the next
in a pre-determined order or at random. Normally up to 20 guard tours can be set up and activated
during different times of the day. In guard tour mode, one PTZ dome network camera can
cover an area where 10 fixed network cameras would be needed. The main drawback is that only
one location can be monitored at any given time, leaving the other nine positions unmonitored.
The optical zoom of a PTZ dome typically ranges between 10x and 35x. A PTZ dome is often used
in situations where an operator is employed. This type of camera is usually mounted on a ceiling
if used indoors, or on a pole or wall of a building in outdoor installations.
Figure 2.2f PTZ dome network cameras. From left to right: 231D+, 232D+, 233D.
Day and night network cameras
All types of network cameras—fixed, fixed dome, PTZ, and PTZ dome—can offer day and night
functionality. A day and night camera is designed to be used in outdoor installations or in indoor
environments with poor lighting.
A day and night, color network camera delivers color images during the day. As light diminishes
below a certain level, the camera can automatically switch to night mode to make use of nearinfrared
(IR) light to deliver high-quality, black and white images.