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Communication and tracking system performance 153

Table 8.11 Summary of predicted and measured results
Predicted Measured

Primary AA 221 170
SDA 193 112
90% CD 605 420
Secondary AA 209 158
SDA 205 126
90% CD 504 601

8.5 Conclusions

This chapter describes a realistic and simulated deployment of a communications and
tracking system with complete analysis of the system’s performance. There are
13 FMNs underground, 2 FMNs above ground, and three BCNs located at strategic
areas. Using anticipated loss parameters for the Test System radio signals, fresh air
and belt air entries of the mine are simulated in order to calculate anticipated perfor-
mance metrics. Several dozen physical tests of the designed and described Test Sys-
tem are compared to predicted results.
Predicted results proved to be higher in most metric values that are measured; how-
ever, measured results are collected by a device that is continually measuring loca-
tions, but predictions are from single point values. A comparison technique was
used to gather all data collected in both prediction and measurement cases. Variations
in this comparison technique have a large impact on measurements. This is especially
true when a survey was conducted for a long period of time in a small area. Values col-
lected during that time will have a greater impact on the overall average because there
are more of them, than in an area that was visited less or for a shorter period of time. This
is further complicated by the internal reporting intervals of the tracking system. Many
systems report the current location of a tracked device and the duration at that location.
They do not report the number of times the device was reported to be at that location.
A smoothing algorithm that is easy to understand needs to be developed to solve the time
and location weighting problems that can be caused during measurements.
This chapter describes a method of predicting the performance of a tracking system
that is in line with the observed performance. More importantly, it demonstrates that
the predicted measures and observed values using standardized metrics do describe
the same tracking system because general values and trends are correct. The magni-
tude of changes can be adjusted with simulation input parameters, changing values to
be more specific to that location.
Communication and tracking systems have rapidly become critical to operations at
the most efficient mines in the United States. The Test System presented is significantly
smaller than the typical system found in a producing mine; however, the techniques for
planning, verification, and optimization of tracking systems described in this chapter