User's Manual Part 2
Release8PlanningGuide
Issue2,November2007 Draft5forRegulatoryReview 153
Furthermore, a BH and an AP on the same tower require that the effects of their differing
receive start times be mitigated by either
◦ 100 vertical feet (30 meters) or more and as much spectral separation as
possible within the same frequency band range.
◦ the use of the frame calculator to tune the Downlink Data % parameter in each,
so that the receive start time in each is the same. See Using the Frame
Calculator Tool (All) on Page 444.
Spectrum Analysis (Not available on Cyclone OFDM modules)
You can use an SM or BHS as a spectrum analyzer. See Mapping RF Neighbor
Frequencies on Page 131. Through a toggle of the Device Type parameter, you can
temporarily transform an AP into an SM to use it as a spectrum analyzer.
Power Reduction to Mitigate Interference
Where any module (SM, AP, BH timing master, or BH timing slave) is close enough to
another module that self-interference is possible, you can set the SM to operate at less
than full power. To do so, perform the following steps.
CAUTION!
Too low a setting of the Transmitter Output Power parameter can cause a link
to a distant module to drop. A link that drops for this reason requires Ethernet
access to the GUI to re-establish the link.
Procedure 3: Reducing transmitter output power
1. Access the Radio tab of the module.
2. In the Transmitter Output Power parameter, reduce the setting.
3. Click Save Changes.
4. Click Reboot.
5. Access the Session Status tab in the Home web page of the SM.
6. Assess whether the link achieves good Power Level and Jitter values.
NOTE: The received Power Level is shown in dBm and should be maximized.
Jitter should be minimized. However, better/lower jitter should be favored over
better/higher dBm. For historical reasons, RSSI is also shown and is the unitless
measure of power. The best practice is to use Power Level and ignore RSSI,
which implies more accuracy and precision than is inherent in its measurement.
7. Access the Link Capacity Test tab in the Tools web page of the module.
8. Assess whether the desired links for this module achieve
• uplink efficiency greater than 90%.
• downlink efficiency greater than 90%.
9. If the desired links fail to achieve any of the above measurement thresholds, then
a. access the module by direct Ethernet connection.
b. access the Radio tab in the Configuration web page of the module.
c. in the Transmitter Output Power parameter, increase the setting.