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Time Distance Diagrams |
A time distance diagram decribes
the movement of an object depending on the distance which the
object has covered and the elapsed time. In this context the term "object" is kept very
abstract
because an object can represent all sorts of things which are able to move.
The objects in the training module are trains, because the training module focuses on
the application of time distance diagrams as
timetables.
First of all time distance diagrams are
two-dimensional coordinate systems.
In such a coordinate system the axis of ordinates represents the elapsed time and the axis of abscissae
represents the covered distance.
Fixed places on the axis of abscissae, where the objects range between,
are marked by a vertical line. In the use case of timetables, the places are normally
railway stations which are marked by a vertical line on the horizontal axis and a label (see Figure 4).
The labels at the top of a lines show the identifiers which represent the names of the stations.
Figure 4
Normally the movement described by a time distance diagram could be linear or curved, depending on
whether the tempo of an oject is constant or not.
Within the training module the tempo of the trains between two stations is constant.
As shown in Figure 4, in our training module the movement of a train will be displayed as a
colord linear curve in the diagramm.
A movement curve represents the timetable of a train. It defines at which time the train arrives at a station
or leaves it, respectively. That means, each color represents a certain train.
In the most cases the context of a time distance diagram determines if the time is measured in
hours, minutes, seconds or in an abstract time unit. The training module provides two kinds of
time scale. On the one hand you can choose the scaling in hours, minutes and seconds
(see Figure 5 right) and
on the other hand you can choose the scaling in abstract time units, also called steps (see Figure 5 left).
More details on the time scale you will find in the chapter
Set Time Range.
Figure 5
In the diagrams of the training module
the stations are placed with equal distances along
the horizontal axis. A correct representaion of the spatial placement of the stations is given by
a map.
With the map you can arrange the stations in a way that the distance between them and
their positions are represented correctly.
(see Figure 6).
More details on the building and editing of a map you will find in the chapter
Map.
Figure 6
In the following subsections you will learn more about the working with time distance diagrams. In this context you will learn to create, to edit, to color and to delete stations and timetables. Furthermore, you will see how to set up the time range of a diagram or how to check a time distance diagram for correctness and consistency.
Introduction > Time Distance Diagrams
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