b. Line AB, which runs from the sump 1 to the utilidor vent in Figure 5. Arrow A points to the sump
1 response and arrow B to the probable response of the utilidor vent. The vent response migrates to a slope,
which indicates increasing distance from the utilidor. The slope originates at 25 m and may indicate a
positional error. The sump response at the vent is probably the diffractions indicated as C. The spread of
sewage in both sumps suggested by the migration is believed to be far too small.
Figure 12 (cont'd).
(arrow B), occurs at a delay of 70 ns and, given a
which suggests that we may have been off the cen-
depth of 6.9 m from our verification survey, corre-
ter of the utilidor. In addition, the time section mi-
sponds to an nm = 1.52. Although this value
grates to a one-sided dipping reflection, rather
agrees well with our migration refractive index of
than a point, as would happen for a fixed target
1.54, snow nearer the surface is of less density, as
(the roof) whose distance increases from the radar
we have seen above, and is more likely to have an
receiver. The difficulty with this explanation is that
n = 1.3. This would place the actual distance to
the dipping reflection appears to originate at a 25-
the roof at about 7.7 m at the 29-m distance,
m distance. Resolution of this problem is not possi-
13
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