Air Live POE-260 CAM, Руководство пользователя

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9. Technical Specification
AirLive POE-260CAM User’s Manual 152
computer, or it can be a standalone hardware device.
„
Focal length -
Measured in millimeters, the focal length of a camera lens determines the width of the
horizontal field of view, which in turn is measured in degrees.
„
FTP (File Transfer Protocol) -
An application protocol that uses the TCP/IP protocols. It is used to exchange files
between computers/devices on networks.
„
Frame -
A frame is a complete video image. In the 2:1 interlaced scanning format of the RS-170
and CCIR formats, a frame is made up of two separate fields of 262.5 or 312.5 lines
interlaced at 60 or 50 Hz to form a complete frame, which appears at 30 or 25 Hz. In
video cameras with a progressive scan, each frame is scanned line-by-line and not
interlaced; most are also displayed at 30 and 25 Hz.
„
Frame rate -
The frame rate used to describe the frequency at which a video stream is updated is
measured in frames per second (fps). A higher frame rate is advantageous when there
is movement in the video stream, as it maintains image quality throughout.
„
Full-duplex -
Transmission of data in two directions simultaneously. In an audio system this would
describe for example, a telephone systems. Half-duplex also provides bi-directional
communication, but only in one direction at a time, as in a walkie-talkie system. See
also
Simplex
.
„
Gain -
Gain is the amplification factor and the extent to which an analog amplifier boosts the
strength of a signal. Amplification factors are usually expressed in terms of power.
Decibel (dB) is the most common way of quantifying the gain of an amplifier.
„
Gateway -
A gateway is a point in a network that acts as an entry point to another network. In a
corporate network for example, a computer server acting as a gateway often also acts
as a proxy server and a firewall
server. A gateway is often associated with both a router, which knows where to direct a
given packet of data that arrives at the gateway, and a switch, which furnishes the
actual path in and out of the gateway for a given packet.