GE Security Legend IP, Installation Manual

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Legend IP
Installation Manual
12
System planning
Before you install and program your surveillance equipment, make sure that you have planned a system that
will meet your needs. You need to balance the various network issues that affect the compression and
transmission of video to get the video quality, transmission speed, and storage capacity that you need your
system to deliver. Consider each of the following related issues.
If you have questions that this section does not answer, GE Security has system design engineers available to
help you design your system. Contact your dealer, sales representative, or GE Security at
www.gesecurity.com .
Digital video networks
Network topologies can be quite different between the design of a single building with a high-speed network
and the design for a number of satellite locations being managed by a central location. If you are connecting
remote offices to each other or to a central office, you must consider the network throughput, latency, and
bandwidth when defining the speed and capacity of a network. Bandwidth is the physical component that is
most easily controlled.
• Throughput is the amount of data that can be transmitted over a network connection in a fixed amount
of time, which is usually expressed as bits per second (bps) for digital devices and as cycles per second
(Hz) for analog devices. The higher the throughput, the faster the transmission speed will be.
• Latency is the a
mount of time it takes a packet to travel from a source to a destination. The
lower the latency, the faster the transmission speed will be.
• Bandwidth is the actual capacity of a network cable. The higher the bandwidth, the faster the
transmission speed will be.
Bandwidth
First, determine what your video payload (amount of video data, not operational data) is likely to be, then
determine how fast you need your video to transmit through the network. After you have considered such
issues as resolution (
Video resolution standards on page 15), data rate ( Video compression standards and data
rates on page 15), throughput, and latency, you can determine what capacity you need your network cable to
be. Real-time digital video generally requires the bandwidth found on high-speed (gigabit-per-second) LAN
networks for reasonably high resolution, bitrate, or channel count.
Table 5 shows a range of sample bandwidths. For help analyzing your system, contact GE Security System
Design or Technical Support.
Table 5. Sample bandwidth requirements for 1 to 48 high-quality, MPEG-4 video streams
Video resolution
standard
fps (frames per
second)
Bandwidth by number of streams in Mbps (megabits per second)
1 4 8 16 24 32 48
D1 30 2.42 9.68 19.36 38.72 58.08 77.44 116.16
D1 15 1.27 5.09 10.18 20.36 30.54 40.71 61.07
2CIF 15 0.70 2.72 5.44 10.88 16.32 21.76 32.64