Computer Networks and distributed Systems

as part of the BMBF-Compound Project SIMBA — „Key Concepts of Informatics in multi medial Elements under special Consideration of Women's specific Learning Interests”

Advice for Teachers - Coding Methods

This component deals with the three coding methods NRZ (Non-Return to Zero), NRZI (Non-Return to Zero Inverted), and Manchester.

The illustration below shows a section from the visualization flow, where, according to a randomly generated bit sequence displayed in the top line, the respective codings may be seen in the lines below. As for the Manchester coding a clock signal is required, the signal is included additionally in the line labelled with Clock.

Illustration 1: Visualization of the codings according to the respective bit sequence

On top of that there is the possibility to determine and enter the respective coding signals according to a sequence of bits originated by a random generator for practice reasons.

To do so the respective signal levels are located on the marked spots simply by point-and-click.
This possibility is suited especially well for students to check upon their skills, since the exercise component reacts to answers automatically, giving corresponding feedback. The respective possibilities exceed traditional exercises, in which teachers only give some values statically to be worked on. Moreover, through the automatic generation of exercises, there is the possibility to repeat practice activity until the students have gained enough competence in dealing with the methods. The manual creation of exercises is connected with working time, an aspect which is not to be neglected, as for the different learning types a different number of exercise runs is needed.

Illustration 2: Exercise on coding a given bit sequence

The didactic surplus, in addtion, is founded on the two-stage evaluation. The student, at first, is only informed on how many mistakes he/she made, however, not where they occurred, and is this way given the opportunity to correct his/her solution. If this procedure was realized by tutors, a great amount of work would be involved.

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