Axis 2400+ Manuale Utente Scaricare il pdf (Pagina 38)

T1 connection

Sometimes referred to as a ‘DS1 line’, a T1 connection

is a dedicated phone line that supports data rates up to

1.544 Mbit/sec. For a ﬁ xed fee every month, you can

connect to the Internet for as long as you want. This stan-

dard is particularly popular among large companies.

10 Mbit Ethernet

Used within ofﬁ ce buildings, this is a network architec-

ture that supports data transfer rates of up to 10 Mbit/s.

There are two main standards for this type of network:

10 BaseT, which uses twisted pair cables, and 10 Base2,

which uses coaxial cables. 10 Base2 is not particularly

popular as it can be unreliable. If there is a break any-

where in the coaxial cable, the whole network stops

working. Due to frequent data collisions only about

50% of the full 10 Mbps network capacity is normally

available. The use of switches eliminates these collisions

to allow full utilization of the network.

100 Mbit Ethernet

This network architecture supports data transfer rates

of up to 100 Mbit/s and the main standard is called 100

BaseT. Although newer and faster than 10 Mbit Ethernet,

in all other respects it is the same.

1000 Mbit Ethernet, Gigabit Ethernet

This is expected to become the most commonly used

system for large companies in the future. Today, however,

this more recent version of Ethernet is most often used

for backbones in buildings. The main standard is called

1000 BaseT.

Cellular phone modems,

e.g. GSM, GPRS, CDMA, CDPD, TDMA

Using cellular phone modems is a good way to access

remote cameras, e.g. cameras for trafﬁ c monitoring.

No telephone cables are needed. The transmission

speed is low, but sufﬁ cient for still images. Typical

communication speeds range from 5-20 kbit/s. You can

connect directly from a PC to a remote camera, using a

standard modem for the computer and a radio modem

for the network camera.

Wireless network, e.g. IEEE 802.11b

Cabling often represents the biggest cost in an installa-

tion, which is why radio networks without cabling, are

becoming increasingly popular.

IEEE 802.11b, also known as wireless Ethernet or

WLAN, is designed to help network engineers imple-

ment totally wireless networks.

802.11b uses direct sequence spread spectrum techno-

logy over the 2.4 GHz ISM band providing 11 Mbps com-

munications speed without line-of-sight requirements.

802.11b supports ranges of up to 300 meters in the

open air and 50-100 meters in ofﬁ ce environ ments.

802.11b is also referred to as Wi-Fi.

Bluetooth wireless networks

Bluetooth is an increasingly popular short-range

radio technology. Bluetooth is a low-cost, low power-

consumption standard, which allows multiple mobile

devices to com municate with each other wirelessly.

Blue tooth uses frequency-hopping technology over the 2.4

GHz ISM band providing up to 723 kpbs communica tions

speed without line-of-sight requirements. Bluetooth

supports ranges of up to 10 meters client-to-client in

open air and 5 meters in-doors with the low-power

version. Due to low bandwith, Bluetooth is not suitable

for video.

Power Over LAN

Now with Power over LAN it is possible to carry power

to the camera on the same cable as that used for network

connection. This is especially suited for IP Surveillance

and remote monitoring applications - to reach places

that were previously thought of as impractical or too

expensive to connect to a power outlet.

Proprietary Power over LAN products have been

around for a few years. They have primarily been used

to power IP phones and wireless access points.

The Power over LAN Midspan connects to an exis-

ting Ethernet or Fast Ethernet infrastructure via any

standard Category 5 cabling. By sending -48 V over

100 meters, Ethernet terminals can be powered by the

Midspan. The Midspan is fully compatible with IEEE

802.3 standard (when no inline power is supplied). It

is also IEEE 802.3af compliant, enabling compatibility

with PoE products.

N ETWORK BASICS

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Axis 2400+ Manuale Utente Pagina 38

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