Measurement Analysis - Motorola PTP 500 Series User Manual

7.9.3 Measurement Analysis

Spectrum Management uses statistical analysis to process the received peak and mean
measurement. The statistical analysis is based on a fixed, one minute, measurement
quantization period. Spectrum Management collects data for the specified quantization period
and only at the end of the period is the statistical analysis performed.
The analysis produces three key metrics for each channel:
Peak of Means
This 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
This 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
This is the arithmetic mean of the measured means during a quantization period. 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.
NOTE
The arithmetic mean is the true power mean and not the mean of the values
expressed in dBm.
Spectrum Management uses the 99.9% percentile as the prime interference
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.
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