f/Stop
Also called F Number and F System. Refers to the speed or ability of a lens to pass light. It is calculated by dividing the focal length of the lens by its diameter.
Fast lens
Having a larger iris (and smaller F-stop), a fast lens gathers and transmits increased light to a surveillance camera.
FCC (Federal Communications Commission)
This United States commission regulates communications by setting rates, controlling broadcast licensing, and testing electronic equipment to RF (radio frequency) transmission and related standards.
Fence disturbance sensor
The perimeter fence around a site may have one of these installed around it for intrusion detection. These sensors can be interfaced with a CCTV switcher so that specific cameras are activated in an area where the disturbance is detected.
FI (Fixed Iris)
These widely used fixed focal length iris lenses are inexpensive and are found in smaller types of fixed CCTV security cameras, usually small case or dome cameras.
Fiber Optics
These high-speed computer-networking cables transmit data using light instead of copper.
Field
One of the two equal but vertically separated parts into which a television frame is divided in an interlaced system of scanning. A period of 1/60 second separates each field start time.
Field of View
The maximum angle of view that can be seen through a lens or optical instrument.
Firewall
A firewall is a software or hardware application installed on a home or office computer that is intended to prevent unauthorized users from accessing that computer. With hacking and network intrusions on the rise, they are becoming essential in protecting private information. Four popular types of firewall are packet filtering, application gateways, circuit-level gateways, and proxy servers. Although they can be difficult to configure correctly, they are a critical component to protect unauthorized access and hacking of IP based surveillance systems that are LAN based.
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