User's Manual

IDS Ingegneria Dei Sistemi S.p.A. N doc: MN/2009/028 - Rev. 1.1

DETECTOR DUO SYSTEM – User manual

As can be seen in Fig. 7.2, the echo of a target doesn’t simple consist

of a single dark band, it consists of alternate dark and light bands.

These derive from the signal minimums and maximums reflected back

from the target (in fact, the black and white bands represented in the

figure correspond to maximum and minimum signal amplitude

respectively). A hyperbolic echo can be used to convert the ordinate of

the map from time (nanoseconds = ns) to depth (meters= m). To do

this, the hyperbola traced in ns ordinates is compared with a family of

hyperbolas traced with ordinates in meters, obtained from that in ns

ordinates with various values of

. The best

approximation to the

real value is that with the most similar aperture to that of the one

traced in time ordinate. Once

has been identified, the depth of the

target corresponding to the hyperbolic section can be found. There are

no definitive criteria for interpreting diagrams and often you have to

depend on experience. In any case, it is best to collect the largest

possible amount of information for an area under investigation, and

use it to help choose the most appropriate equipment and investigation

parameters. To conclude, we have an example below of a real situation

featuring two pipes side by side (Fig. 7.3). This example is significant

in that it shows the diagrams of the same structure (the pipe) placed

perpendicularly then parallel to the direction of investigation.

Fig. 7.3 – Example of map interpretation

Scan 3

Pipe

topography

PIPE

Scan 1

Scan 2

PIPE