Wave Wireless Networking SC5800, User Manual, Page: 23 / 108

SPEEDCOM SC5800 User Manual
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3.4 Interference Considerations
The ISM frequency bands are used by devices that can cause interfe rence to the
SC5800 radio system. Interference can be avoided by careful planning of the
system installation. The available methods for providing isolation from interfering
radiators are the following:
•
Frequency diversity
•
Antenna polarization
It is recom mended to scan the proposed installation areas (using a spectrum
analyzer) to establish the presence of interference. The frequency spectrum should
be scanned over a sufficient time period to ensure that periodic transmissions are
recorded.
Interferers will cause problems if their amplitudes are not more than 20 dB below the
intended receive power level. A link path loss calculation should be performed to
determine the expected receive power level.
The procedure for selecting the optimum antenna polarization and system frequency
plan is the following:
•
Perform a spectral analysis at each site in the link direction using a high gain
antenna.
•
Repeat the spectral analysis for vertical and horizontal polarization.
•
Select the polarization with the lowest interfering levels as the system
antenna polarization.
•
Consult the SC5800 frequency channel plan as shown in Section 2.2.1,
Frequency Plans , page 12. Then, select the frequency plan that would operate
in an interference-free band. Give preference to channel plans A, B and C as
these are optimized for best receiver sensitivity.
•
Install the ‘High Band’ and ‘Low Band’ Outdoor Units at the sites where they
would experience the lowest interference in their respective receive bands.