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Communication and tracking system performance 141

The thousands of values calculated are filtered by area and then ordered by IA.
Because of the large number of samples, the 90th percentile is found at an IA. These
simulations predict a 90% CD of 185ft in the primary EW, 162ft in the secondary EW,
and 254ft within the belt entry.

8.4 Measurement of tracking system performance

The tracking system described earlier was installed with care taken to keep infrastruc-
ture devices in simulated locations. Data were collected over the course of several
months and several surveys to compare with simulation results. Several tests were
designed to isolate specific effects that may impact the tracking system. In addition,
the Test System was installed in the Example Mine on behalf of the research project
and is the secondary system, allowing the research team to modify the system. The
system is not installed to the working face in the Example Mine. The most inby node
is located at a turn in the main entries.

8.4.1 Measurement of tracking system variations when stationary

In order to gain an understanding of the variation in the tracking system with the least
number of perturbations, a device was hung from a roof bolt on 10-25 from 11:44:00
until 12:47:57. The device was hung at the location 1907839, 350827. Measured
results at this location were: AA of 99.5, SDA of 19.4, AEV of h40, 4i, and ACR
of 84. Selected records from the tracking database are in Table 8.2 with a map of
the GTP and TSPs in Fig. 8.27.
Next, the device was hung from a roof bolt on 10-26 from 10:15:54 until 11:57:00.
The device was hung at the location 1905962, 350799. Measured results at this loca-
tion were: AA of 79.7, SDA of 33.6, AEV of h 46,3i, and ACR of 48.8. Selected
records from the tracking database are in Table 8.3 with a map of the GTP and TSPs
in Fig. 8.28.
The handset hung in the secondary EW is compared to the prediction values for that
same location. Fig. 8.29 shows locations calculated by the tracking system in red and
predicted values in black. The actual location of the handset is circled in red and the
prediction location is a blue point. Tracking system locations are taken from surveys
performed in the area, not including values from the stationary handset test described
earlier. TSP values in the following figures and tables are taken from surveys con-
ducted with the survey buggy, described later. Figures indicate that prediction values
describe the same sort of distribution, but are trending more toward the other
escapeway than calculated values. Table 8.4 shows metric values for this single loca-
tion. AA, SDA, 90% CD, and ACR values from the prediction and the measured are
within an acceptable range. AEV describes the predicted values to be further toward
the primary EW.
The stationary handset in the primary EW (see Fig. 8.30) was placed at the location
circled in red. Red points are calculated by the tracking system and black points are
predicted points. The clustering of locations in this escapeway is the opposite of