User's Manual

20 MDS iNet 900 Installation Guide MDS 05-2873A01, Rev. A
DRAFT 6—8/29/01
Antenna SWR Check (Z? Major revision needed?)
It is necessary to briefly key the transmitter
1
Z? for this check by placing
the radio in the
SETUP mode (page 42) and using the KEY command on
the HHT. (To unkey the radio, enter
DKEY; to disable the setup mode and
return the radio to normal operation, enter
Q or QUIT.)
The SWR of the antenna system should be checked before the radio is
put into regular service. For accurate readings, a wattmeter suited for
1000 MHz is required. One unit meeting this criteria is the Bird Model
43
™
directional wattmeter with an 5J element installed.
The reflected power should be less than 10% of the forward power (≈2:1
SWR). Higher readings usually indicate problems with the antenna,
feedline or coaxial connectors.
If the reflected power is more than 10%, check the feedline, antenna and
its connectors for damage.
5.0 TRADITIONAL REPEATER
CONFIGURATION WITH TWO
RADIOS
5.1 Overview
Two MDS iNet 900 radios may be connected “back-to-back” through
the
LAN Ports to form a repeater station. (The cable must be a
“cross-over” Ethernet cable for this to work). This configuration is
sometimes required in a network that includes a distant Station Adaptor
that would otherwise be unable to communicate directly with the Access
Point station due to distance or terrain.
A repeater works by re-transmitting data from the outlying remote site
to the Access Point station and vice versa. It introduces a small amount
of end-to-end transmission delay, but this is not a problem in most sys-
tems.
The geographic location of a repeater station is especially important. A
site must be chosen that allows good communication with both the
Access Point and the outlying remote site. This is often on top of a hill,
or other elevated terrain from which both sites can be “seen” by the
repeater station antennas. A detailed discussion on the effects of terrain
is given in Section 3.2, Site Selection (beginning on page 6).
The following paragraphs contain specific requirements for repeater
systems.
1. Is it true that we still need to key the transmitter to use the RSSI function to
aim the antenna?