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Application Notes
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Digital Terminology
| Term |
Description |
| Codec |
Coder/Decoder:
A codec can both code (or encode) an analogue signal to a digital one and conversely can decode a digital signal back to an analogue one. The process of coding is a tradeoff with speed/accuracy/size of data - all controlled by the compression functions, eg mpeg-4. |
| DVR |
Digital Video Recorder:
Records analogue video signals onto computer hard disks by digitising and compressing each input signal. |
| Gbit LAN |
A local area network running at 1Gbit/s (1000 MBit/s). Also termed 1000BASE-T
The cabling required is Cat 5e copper twisted pairs.
Ethernet defines the wiring and signalling standards.
Earlier standards:
Fast Ethernet:
100BASE-T : 100 MBit/s
10Mbit/s Ethernet:
10BASE-T : 10 MBit/s
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| Hybrid |
Hybrid:
A hybrid system is one with combined analogue and digital equipments. |
| IP Network |
Internet Protocol Network:
A collection of IP devices all on the same network. The network could be restricted to few devices on a LAN or it could be 1000's of devices all spread around the internet. |
| IP Number |
Internet Protocol Number:
Every device on a network must have a unique number, eg 192.168.1.24.
Also called IP Address |
| LAN |
Local Area Network:
A LAN is typically a group of devices connected on a network in a small physical area, eg an office or control room. LAN's can be created with a single network switch (hub) and network cables (cat 5, cat 6).
LAN's are very fast and rated upto 1 Gbit/s.
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| NVR |
Network Video Recorder:
Records digital video signals direct from the IP network. An NVR therefore has only digital inputs and digital outputs. NVR's can be located anywhere on the network. |
| TCP/IP |
Transmission Control Protocol/Internet Protocol:
This is a suite of protocols that defines how all the devices on the network communicate with each other. |
| WAN |
Wide Area Network:
a WAN is a collection of LAN's, connected to each other typically by routers; this is how the internet is structured. WAN's can be reasonably fast , but they are limited by the slowest device in the chain. |
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