102 MDS iNET 900 User’s Guide MDS 05-2806A01, Rev. A
may be necessary to mount the station antennas higher, use higher gain
antennas, select a different site or consider installing a repeater station.
To prepare the equipment 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-4 TROUBLE-
SHOOTING & RADIO MEASUREMENTS section Page 85.
5.1.6 A Word About Radio Interference
The iNET 900 units share 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.
1. Systems installed in rural areas are least likely to encounter
interference; 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.
2. Use a directional antenna at remote sites whenever possible.
Although these antennas may be more costly than omnidirectional
types, they confine the transmission and reception pattern to a com-
paratively narrow lobe, that minimizes interference to (and from)
stations located outside the pattern.
3. If interference is suspected from a nearby licensed system (such as a
paging transmitter), it may be helpful to use horizontal polarization
of all antennas in the network. Because most other services use ver-
tical polarization in this band, an additional 20 dB of attenuation to
interference can be achieved by using horizontal polarization.
Another approach is to use a bandpass filter to attenuate all signals
outside the 900 MHz band.
4. Multiple iNET 900 Access Point units can co-exist in proximity to
each other with only very minor interference as long as they are
each assigned a unique network name. Each network name has a
different hop pattern. (See “Protected Network Operation through
Multiple Access Points” on Page 11.) Additional isolation can be
achieved by using separate directional antennas with as much verti-
cal or horizontal separation as is practical.
To Next Page
Loading...
