GE MDS MDS iNET 900, Reference Manual

Page: 146 / 190

136 iNET Series Reference Manual 05-2806A01, Rev. H
4.1.6 Conducting a Site Survey
If you are in doubt about the suitability of the radio sites in your system,
it is best to evaluate them before a permanent installation is underway.
This can be done with an on-the-air test (preferred method); or indi-
rectly, using path-study software.
An on-the-air test is preferred because it allows you to see firsthand the
factors involved at an installation site and to directly observe the quality
of system operation. Even if a computer path study was conducted ear-
lier, this test should be done to verify the predicted results.
The test can be performed by first installing a radio and antenna at the
proposed Access Point (AP) station site (one-per-system). Then visit the
Remote site(s) with another transceiver (programmed as a remote) and
a hand-held antenna. (A PC with a network adapter can be connected to
each radio in the network to simulate data during this test using the
PING command.)
With the hand-held antenna positioned near the proposed mounting
spot, a technician can check for synchronization with the Access Point
station (shown by a lit
LINK
LED on the front panel) and measure the
reported RSSI value. (See “ Antenna Aiming” on Page 141 for details.)
If adequate signal strength cannot be obtained, it may be necessary to
mount the station antennas higher, use higher gain antennas, select a dif-
ferent site or consider installing a repeater station. To prepare the equip-
ment for an on-the-air test, follow the general installation procedures
given in this guide and become familiar with the operating instructions
found in the
CHAPTER-2 EMBEDDED MANAGEMENT SYSTEM
section Page 19.
4.1.7 A Word About Radio Interference
The transceiver shares the radio-frequency spectrum with other 900
MHz services and other Part 15 (unlicensed) devices in the USA. As
such, near 100% error-free communications may not be achieved in a
given location, and some level of interference should be expected. How-
ever, the radio’s flexible design and hopping techniques should allow
adequate performance as long as care is taken in choosing station loca-
tion, configuration of radio parameters and software/protocol tech-
niques.
In general, keep the following points in mind when setting up your com-
munications network.
• Systems installed in rural areas are least likely to encounter interfer-
ence; those in suburban and urban environments are more likely to
be affected by other devices operating in the license-free frequency
band and by adjacent licensed services.
• Use a directional antenna at remote sites whenever possible.