Motorola MOTOWI 4 User Manual page 99

Peak of Means
99.9% Percentile of the Means
Mean of Means
Peak of Means:is the largest mean interference measurement encountered during the quantization
period. The peak of means is similar to the peak of peaks and is useful for detecting slightly longer
duration spikes in the interference environment. 99.9% Percentile of the Means is the value of
mean interference measurement which 99.9% of all mean measurements fall below, during the
quantization period. The 99.9% percentile metric is useful for detecting short duration repetitive
interference that by its very nature has a minimal effect of the mean of means.
Mean of Means:is the arithmetic mean
The mean of means is a coarse measure of signal interference and gives an indication of the
average interference level measured during the quantization period. The metric is not very good
at predicting intermittent interference and is included to show the spread between the mean of
means, the 99.9% percentile and the peak of means.
Important Note:
measurement. All subsequent references to interference level refer to this percentile measurement.
The display of statistical measurement on the spectrum management page always shows a statistical
summary of all channel measurement. The statistical summary is controlled by the Statistics
Window attribute. This attribute defaults to a value of twenty minutes, which means that the
mean and percentile values displayed for each channel are calculated over the 20 minute period.
All channel decisions are made using the values computed over the statistics window period.
8.3.7.4 The Spectrum Management Master / Slave Relationship
The Spectrum Management operates in a master / slave relationship. The master is assumed to be
the link master configured during installation. All Spectrum Management configuration changes
MUST be performed from the master. To enforce this, the Spectrum Management web page has
a different appearance depending if you are viewing the data from the master or slave.
All configuration changes are applied at the master only. These changes are then messaged from
the master to the slave. Any Spectrum Management configuration messages received at the slave
are stored in non-volatile memory. This enables both master and slave to keep identical copies of
Spectrum Management configuration data in their non-volatile memories. It is therefore possible
to swap master and slave roles on an active Point-to-Point link without modifying Spectrum
Management configuration.
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The arithmetic mean is the true power mean and not the mean of the values expressed in dBm.
Web Page Reference
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Spectrum Management uses the 99.9% percentile as the prime interference
of the measured means during a quantization period.
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