Microhard Systems pMDDL5824, Руководство по эксплуатации

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6.0 Installation
The are a number of factors to consider when preparing to deploy a radio network, several of
which have been touched - upon or detailed elsewhere within this manual. Following is a listing
of a number of factors, in no particular order:
Network Topology
The pMDDL5824 currently supports Master and Slave modes which can create either Point to
Multipoint or Point to Point network topologies.
Throughput
The pMDDL5824 is capable of up to 25 Mbps throughput. The network topology has an effect
on how this available throughput is ‘ shared ’ between all nodes on the network.
Distance
The physical distance between the modems dictates such things as required antenna perfor-
mance and heights. When contemplating antenna types, keep in mind the directivity
(omnidirectional or directional) of the antennas being used.
Terrain
Along with distance, the terrain is a very important consideration with respect to antenna height
requirements. The term ‘ line - of - sight ’ (LOS) refers to being able to ‘ see ’ one location from anoth-
er - a minimum requirement for a radio signal path. In addition to LOS, adequate clearance
must also be provided to satisfy ‘ Fresnel Zone ’ requirements - an obstruction - free area much
greater than the physical LOS, i.e. LOS is not enough to completely satisfy RF path require-
ments for a robust communications link.
Transmit Power
Having read thus far through the factors to be considered, it should be clear that they are all in-
terrelated. Transmit power should be set for the minimum required to establish a reliable com-
munications path with adequate fade margin. Required transmit power is dictated primarily by
distance, antenna type (specifically the ‘ gain ’ of the antennas being used), and the receive sen-
sitivity of the distant modem. Cable and connector losses (the physical path from the modem ’ s
‘ antenna connector ’ to the antenna ’ s connector) must also be taken into account.
Receive Sensitivity
The Pico Series has exceptional receive sensitivity, which can produce a number of benefits,
such as: added fade margin for a given link, being able to use less expensive coaxial cable or
antenna types, being able to operate at greater distances for a given distant transmitter power
(perhaps negating the requirement for a Repeater site!). Distance, antenna gain, transmit pow-
er, and receive sensitivity are critical ‘ numbers ’ for radio path calculations. Fortunately, the Pico
Series features the maximum available transmit power combined with exceptional receive sensi-
tivity - two ‘ numbers ’ which will produce the most favorable path calculation results.
The installation,
removal, or
maintenance of any
antenna system
components must be
undertaken only by
qualified and
experienced
personnel.