1 Introduction
The demands on digital high-speed data communication
equipment
are increasing permanently and so are the demands on the maximum
bandwidth of transmission media [
Na00].
Modern
communication systems need high-speed optical transmitters and
receivers for Terabit data transmission rates. Most of these
communication systems are based on advanced opto-electrical methods
like wavelength division multiplex (WDM), which is one of the most
widely used methods. Likewise, the use of polymer optical fibres (POF)
as an optical transmission medium is expanding rapidly.
The POF is an optical waveguide consisting of a highly transparent
polymeric material. A thin PMMA cladding with a lower refractive index
encircles the PMMA core, causing a total internal reflection, an
optical phenomenon, which always occurs when light strikes a medium
with a lower refractive index and is reflected to almost full extent.
Thus, light cannot leave the waveguide making POF usable for
communication technology.
The current surge in POF uses in especially visible in market growth
– compared to the market for glass optical fibres, the POF
market
is booming. While POF technology has been around since the late 70s,
using polymer fibres for data communication has been a costly business
until the turn of the century when prices for transmitter and receiver
modules in the visible wavelength area (400nm to 800nm) declined,
making a cost-effective use of POF possible [
Da01].
Fig. 1: General
structure of POF (left) and attenuation within the visible
spectrum
(right) [PO07]
According to a recent
study by IGI Consulting [
IGI06],
the increased interest in POF is mostly due to several current
developments in the technical area:
- The demand for cost-efficient high-speed communication
technology is increasing
- European automakers have introduced the POF-based MOST-bus
- The 1394b standard has been introduced, increasing the
distance
between communication nodes to 100m for 3,29 Gbps communication systems
- During the last years, several new POF application fields
have
been found, including home infotainment, industrial Ethernet,
medical technology and sensor technology
Another recent market
study,
conducted by Harz University itself in 2005 among the members of
OPTECNET – the German optical competence networks
–
shows a clearly risen interest in POF technology. More than 50% of all
companies polled are currently in the process of or preparing to expand
the use of POF in their own production activities.
Aside from the automotive industry, the industry expected to most
heavily shift to POF usage over the next years is the home
entertainment sector. A recent market analysis [
Ah07]
confirms, that although wireless communication systems like WLAN or
Powerline Communication have the advantage of relieving the home owner
from actually passing any wires, their data rate as well as their
technical stability compare to badly against the established Fast
Ethernet to make both alternatives viable ones. Lightweight and
transparent POF provide home owners an opportunity, to belatedly
establish a 100MBit/s data connection without too much effort (because
of the extremely simple handling) that is a lot less visible than
regular copper cables. Thus, POF has become increasingly interesting
for the so-called “last mile” – the last
few meters
from any city-wide broadband and glass fibre based network to the end
user.
The increasing importance of POF and WDM systems makes enabling
students and vocational trainees to understand how WDM and/or POF
systems are designed, built and maintianed a paramount task for
universities and other institutions of higher learning or expert
vocational training that offer education in optical technology. This
includes honing the practical skills of students and vocational
trainees and introducing them to concepts such as WDM not only on a
theoretical, but also on a practical, “hands-on”
level.
Fig. 2: As of 2004, the
MOST bus has already been in use in some of the most recognized modern
car types.
Fig. 3: In-house
multimedia infrastructure using POF
In the current academic
setting,
theory is mostly being taught in the classroom while students gain
practical knowledge by performing lab experiments, often using
specially designed lab systems. During such experiments, supervising
educators have to adapt to the individual learning progresses of single
individuals or work groups. In the course of one lab experiment, it is
often necessary to quickly and individually rehearse theoretical
knowledge or to give problem-specific practical advice. This does not
correspond with the idea that students should handle most lab work
autonomously as part of the learning experience. By applying the
principles of augmented learning to photonics training, contemporary
lab work can be brought closer to these ideal conditions.
This paper introduces OPTOTEACH, a newly developed optical teaching
system for photonics training in POF data communication and WDM
methodology. The paper details the technical layout of the system as
well as some of the design concepts behind it. It is then explained,
how the system can be augmented with supplemental, interactive software
and how this combination of lab system and software creates an
effective augmented learning environment.
2 Optical Teaching
Software
OPTOTEACH is the first POF-WDM teaching system,
specifically
designed to cover a multitude of lab experiments in the field of
optical communication technology, e.g. PI curve and bandwidth
measurements or analysis of EMF influences. OPTOTEACH systems are
exclusively built and distributed by HarzOptics, an optics think tank
and research institute associated with the department of Automatation
and Computer Science at Harz University in Wernigerode. OPTOTEACH
systems are currently being used for educational lab work at Harz
University, Braunschweig University, Dresden University, the University
of Mannheim and the Federal Centre for Electronics Technology in
Oldenburg.
OPTOTEACH systems consist of two video transmitters, one LED and one
laser in cw mode and two receivers. The system enables students to
transmit two analogous FBAS video signals or corresponding test signals
with a maximum bandwidth of 10 MHz. Both transmitters operate within
the visible wavelength, which does not only allow OPTOTEACH systems to
be built and maintained at reasonable costs, but also provides students
with an opportunity to visually experience the WDM effect first hand.
The two signals are joined via a conventional Y-coupler developed by
Ratioplast Optoelectronics GmbH , the separation is effected by a
Ratioplast splitter in combination with red and blue colour filters.
Signals can be transmitted over various fibre length, covering 5m up to
100m, whereas the fibre itself is interrupted by a micrometer stage,
enabling the students to analyse coupling losses with cut or polished
fibres as well as lateral and longitudinal misalignments. The general
design of the system can be seen in figure 4.
The system gives students an opportunity to perform a multitude of
experiments, e.g.:
- PI curve measurements
- Bit Error Rate measurement
- Signal quality tests (eye diagram)
- Measurement of bandwidth and S-parameter
- Analysis of EMF influence on the transmission
- Identification of modulation characteristics (AM, ASK, PCM)
- Attenuation measurements for different fibre lengths
(1-100m)
- Attenuation measurements for different wavelengths
(490/520/660nm)
- Analysis of the influence of lateral and longitudinal
misalignments on the transmission
A more detailed description of the teaching system itself can be found
in [
Fi06] and [
Re06].
Fig. 4: General technical layout of the OPTOTEACH lab system [
Re06]
Fig. 5: OPTOTEACH Lab
System with (1)
BNC-Inputs (2) Potentiometer (3) Optical Outlets (4) Polymer Fiber
(POF) (5) Multiplexer (MUX) (6) Shifting Table (7)
Demultiplexer (DEMUX) (8) Polymer Fiber (POF) (9) Optical
Outputs
(10) Potentiometer (11) BNC-Outputs (12) Optical
Powermeter
3 General Software Design
3.1 Basic Requirements
Two basic requirements
can be
determined for teaching software in general: platform independence and
the integration of multimedia content. The software designer has to
make sure, that the software can be used independent from the technical
equipment available in the universities or vocational schools. This
implies, that platform independent technology such as Java or HTML has
to be used at all stages of the software development process.
If HTML is used, if has to be considered, that the terminals used in
the educational institutions will differ from each other in browser
type and version as well as in screen resolution. Thus, the software
has to be thoroughly tested and adapted to the various possible
configurations before being released. The development of teaching
software for any special combination of operating system, browser type
and version as well as screen resolution is economically unsound,
because the customers are forced to adapt their technology to the
software requirements or be content with a lower quality or
hardware-triggered software errors.
Integrating multimedia content into the software application is less of
a technical and more of a didactic necessity. The contemporary software
user generally expects content to be enhanced with multimedia features
and the integration of video films or animations has long been known to
be a good practice for activating the user’s interest and for
making teaching software more appealing [
Te00].
Short video sequences and animations that depict can be used to
visualize scientific theory as well as depicting actual lab work
sequences or experiments. Thus, they can be seen as chapters in a
“taped instruction handbook” and an amendment of
textual
descriptions of experimentation sequences or lab work instructions.
The OPTOTEACH software concept acknowledges these possible problems and
depends solely on multimedia technologies, that do not require any
plugins (such as animated GIFs) or standard plugins that can reasonably
be expected on most of all currently used lab terminals (such as
Macromedia Flash).
3.2 Navigation
The direct comparison of online questionnaires in market research and
interactive teaching software reveals a common design problem: Should
contextual information be placed on one scrollable page or should all
content be split into smaller information units that can be displayed
on one single screen each [
Te00].
If at lot of information is displayed on one single page, the overall
theoretical context can be compassed almost instantaneously by the
student. This prevents any feelings of being confronted with a
seemingly endless number of smaller information screens and allows
students to get a quick overview of the entire content and to guess the
approximate reading time. Such systems are much less complex
–
from the programmer’s point of view – and are
therefore
easier and quicker to realize than the programming of a more elaborate
system of smaller information screens [
Te00].
On the other hand, presenting the entire content of one chapter or the
entire proceedings of one experiment can entice students into quickly
scrolling through the entire text or completely skip the theory to
start with the experiment right away.
The most fundamental benefit of smaller information screens is, that it
spares students the discomfort of having to scroll through the
information – the navigation is much more concise and brings
about a more comfortable software handling. It is also possible to
easily integrate interposed control questions between the information
screens and to instantaneously validate any given answers, which not
only enables the students to get an immediate feedback on their
learning efforts but also makes it possible for the software to suggest
the targeted repetition of certain theoretical aspects based on the
direct evaluation of the answers given.
The information screen option therefore offers a higher level of
interactivity as well as enhanced possibilities to evaluate student
performance. These advantages and the consequential higher software
quality and enriched learning experience outweigh the higher complexity
in design and programming. To circumvent the aforementioned feeling of
“endlessness”, a progress bar can be included,
which
indicates the remaining number of information screens. Additionally,
the average time of completion can be shown at the beginning of each
self-contained learning module.
Fig. 6: Screenshot of
the current OPTOSOFT beta version (in German language)
The navigation design
should allow a
comprehensive overview of the theoretical content and enable the
student to jump back and forth between the theoretical chapters as well
as follow an “ideal learning path”. A good example
for a
practical and concise navigation design is the popular SelfHTML HTML
learning software. Another exemplary navigation design can be found on
the two online learning sites “Mikro
Online” and
“Makro Online” , developed by Wilhelm Lorenz,
professor of
macroeconomics at Harz University.
After the navigation design is completed, a pre-test should be arranged
along the lines of the conceptual design of any online market research
questionnaire. The pre-test allows a testing of the navigation design
as well as the general visual impression of the software during a phase
of the software development process, in which changes in either the
navigational design or the visual presentation are still possible. The
basic procedure of such a pre-test can be adopted from market research
online pre-testing processes and is described e.g. in [
Po98].
4 Didactic Concept
4.1 Learning Phase
Because the software
aims to support
the entire learning process form theory rehearsals to lab-based
experiments, it is important to break down the complete process into
all methodically different learning phases. Concerning the
OPTOTEACH optical teaching system, these phases are already known from
the direct practical use of the system in various courses at Harz
University:
- Repetition and solidification of theoretical knowledge
- Overview of and support during various lab experiments
- Gathering of measurement data and production of lab
protocols
To decide on the ideal
didactic
concept for the teaching software, the authors extensively researched
the various parallels between online collection of market research
data, especially via online questionnaires, and lab and/or teaching
software within the context of an augmented learning environment. Table
1 contains an excerpt from the list of researched parallels.
Similarities were especially appearant concerning the somewhat limited
user motivation, which is a problem for market researchers as well as
for lab instructors. It is noteworthy that the solution to this problem
consists – in both cases – in the introduction of
an
extrinsic motivational element into the situation, which is known as an
incentive in market research terms – and as a grade for
students.
Both situations demand a certain level of focused mental concentration
on the user side, in both cases data is collected and later analyzed
and the exact technical configuration of the end unser terminals is
unknown to the market research questionnaire designer as well as to the
teaching software programmer. In both cases, no specific technological
requirements (e.g. operating system, browser type, browser version or
number of additional plugins needed) can be made without excluding
potential users. Many more parallels can be found, e.g. concerning the
average time needed to complete a typical online questionnaire or an
average learning module.
| Feature |
Online Questionnaire |
Lab / Teaching Software |
| Level of Motivation |
Low or very low |
Partially low |
| Source of Motivation |
External (Incentives) |
External (Grades) |
| Focus of Participants |
Ususally high |
Mostly high |
| Data Analysis Method |
Analysis of given answers |
Evaluation / Grading |
| Programming |
Java, HTML, CGI |
Java, HTML, CGI |
| User-side IT Technology |
Manifold technology |
Manifold technology |
| Average Duration |
20-30 Minutes |
30-40 Minutes |
Tab. 1: Parallels
between the online
collection of market research data through questionnaires and the use
of teaching software within or outside an augmented learning
environment (excerpt)
Because of these
parallels, it seems
prudent to utilize already existing scientific research on the creation
of ideal conceptual designs for market research questionnaires,
especially the existing Best Practice frameworks, in the development of
teaching software. A thorough review of contemporary online market
research methodology also confirms other findings about the ideal
design of teaching software: direct feedback and a high degree of
interactivity can trigger a heightened involvement on the user side,
the (careful and spare) use of high quality multimedia elements helps
to keep up the user's attention and the best possible solution to
present a larger number of questions (or other content) is splitting
them up in screen-sized information modules.
The application of the most important guidelines in contemporary online
market reasearch questionnaire design (especially the research of [
Te00], [
Dr03],
[
Bö99] and the
most recent [
We05]) lead to
the four basic software modules pictured in fig. 7.
These four modules are: The continuous repetition and cementation of
theoretical knowledge about various aspects of optical technology, the
user-controlled exploration and self-testing of this theoretical
content utilizing interactive graphs and modules such as
multiple-choice questionnaires, the customisable help and support of
lab experiments and the option of generating and saving PDF
protocols with measurement data and student answers to theoretical
questions as a data base which can be utilized by the lecturer for
grading purposes.
Fig. 7: Overview of the
four OPTOTEACH basic software elements
The repetition and
consolidation of
theoretical knowledge is not confined to one theoretical module which
students have to complete before a lab experiment can begin, instead,
theoretical knowledge is repeated throughout the entire experimentation
process and the interpretation of resulting measurement values. The
hypertext-character of HTML allows the implementation of this idea into
the software, because students can use embedded hyperlinks on important
science terms to jump to corresponding theoretical context and then
back to the current experiment. A permanently accessible glossary with
an integrated search function makes it even easier for students to gain
access to important theoretical knowledge. The synergy-effect that
results from the interconnection of hands-on experimental lab work and
understandable overviews of theoretical basics can thus be utilized
most efficiently.
Because the overall design (the single information screen model
mentioned above) allows the easy implementation of interposed control
questions, this additional control method, which is typically not part
of typical educational lab work programmes, can be integrated into the
experimental workflow. It is up to the lecturer or lab administrator to
decide, whether these knowledge checks are mandatory or optional for
students.
The chaperonage of the individual student during lab experiments
– the only part of the teaching software that is currently
still
under development – forms the core of the augmented learning
environment. Parallel to the actual experimental performance students
will be able to inform themselves about the general layout of the
experiment, get work instructions from the computer and enter their
measurement data, whereas average measurement data and other
intermediate results provide the opportunity to continuously check
whether the experiment is conducted correctly. Thus, students will be
enabled to detect any discrepancies in their measurement data at an
early stage and therefore check their own results, which is almost
impossible to realize in a traditional lab environment. In the event of
perceptible deviations of the experimental results from the ideal
results, a set of multiple-choice questions will allow the student to
identify probable causes of the discrepancy and gather instructions for
correcting any possible mistakes. The lecturer only has to get involved
into a particular experiment if this help system does not provide the
solutions needed to achieve the expected results.
The heightened level of autonomy alleviates student-controlled lab work
and supports the pedagogical concept behind of enabling students to
advance their practical skills as well as their theoretical knowledge
more or less autonomously in a self-controlled environment.
The acquisition of measurement data and the compilation of lab
protocols will also be implemented, whereas the software covers all
four learning phases. Via a HTML form field, students can enter
measurement data as well as textual answers to theoretical questions
and questions about completed experiments. This does not only represent
a significant assistance for students but also for lecturers and lab
administrators who will be disburdened from deciphering bad
handwritings and searching for lost sheets of paper.
4.2 Dimensions of Teaching Software
Teaching software, like
the OPTOSOFT
software presented in this paper, is basically defined through the
three dimensions of interactivity, adaptivity and controllability [
DE01]. According to [
Ke98],
interactivity can be seen as a mostly technical dimension: When working
in an interactive medium, the user – in this case the optics
student – has unrestricted and self-controlled access to
multimedia information. The interactivity allows the active processing
of teaching content by the student, who has the ability to influence
the selection and the sequence of content at least partially [
Ja00].
Within OPTOTEACH, interactivity is provided via the easy-to-use
navigation, which allows almost unrestricted access to all content
modules. Students can forgo the recommended “learning
path”
and navigate freely through the software.
Adaptivity is defined as the extent to which users are allowed to
customize any given software [
DE01].
OPTOSOFT allows students to adjust the software to the preferred
working speed, repeat complex passages at will or self-check the
comprehension via multiple choice questions. When the software is used
as a lab companion, the speed of instructions and recommendations is
adjustable to the actual experimental progress, likewise in the
acquisition of measurement data and the compiling of lab protocols,
meaning the dimension of adaptivity is distinctive throughout all four
phases described in 4.1.
According to [
DE01],
controllability does not
refer to the control of the lecturer or lab administrator over the
student but to the control of the student over the learning process. In
computerized learning environments, the controllability increase with
the extent to which non-linear navigation is implemented, meaning the
less restricted the user is, the higher is the controllability of the
software [
Ne00]. Because
the technical basis
of OPTOSOFT is HTML, the hypertext-functionality allows a nearly
completely unrestricted navigation throughout most of the learning
modules. The only restrictions will be implemented into the lab
protocol compilation process, because the electronic documents
generated in this process may provide a basis for student grading.
Because of that, students will only be able to access the protocol
editor after an experiment has been completed instead of being able to
directly jump into the protocol compilation process. Furthermore, the
PDF files generated by OPTOSOFT will exhibit a time stamp unchangeable
by student changes in the protocol editor.
5 First Experiences
At present, more than half of the teaching software is completed, with
the theoretical modules being already fully functional. The software
will soon be undergoing vigorous beta testing at the Harz University
photonics labs. The first student and lecturer feedbacks have been
unanimously positive, welcoming the introduction of the multimedia
element and the easy-to-navigate glossary to the lab. Several technical
problems have been asserted and will be rectified before the release of
the pre-beta-version.
One of the more interesting results of the first feedback evaluation is
the clear demand for more multimedia elements to be included in the
final version, directly connected to the general wish for a more
colourful and less conservative visual design. While these wishes can
certainly be implemented in the pre-beta-version, it is important not
to overload the software with colours and multimedia elements,
preserving the scientific image.
6 Conclusion and Outlook
At this stage, the fully functional OPTOSOFT version 1.0 is expected to
be complete in late 2007, so that universities and vocational schools
can start using the software in class and lab work not later than early
2008. The current version already includes the complete
theoretical learning modules, the knowledge base, the link list, most
of the multiple choice tests and interactive modules as well as some of
the lab companion modules. Other lab companion modules, lab movies and
a fully functional version of the protocol generator are still in
development. The OPTOTEACH lab teaching system also described in this
paper, has already been successfully introduced to the German education
market and, as of early 2007, is being used in more than half a dozen
universities nationwide.
Because the adoption of the augmented learning idea to photonics lab
work is new and untested, the authors are very curious about the
feedback of the first classes and lecturers that will start working
with the software in early 2008. A quality feedback system, that will
allow students and lecturers alike to communicate their experiences and
critique points, is already in an early set-up phase. Aside from the
mostly subjective impressions of students and lecturers, this feedback
system will also gather more objective data such as average grading
before and after the introduction of the software as well as the
results of the teaching quality evaluation during the introductory
period. A quality control and a version management system will ensure,
that didactic and technical change requests are collected, evaluated,
implemented or not implemented and archived for further evaluation.
The continuous further development of teaching system and teaching
software as well as the complete documentation of this development
process will result in a comprehensive catalogue of specifications and
problems in the practical use of an interactive and multimedia lab
companion software in the context of a photonics augmented learning
environment. The authors expect to publish a revised edition of this
catalogue as a basis for discussion about the optimal way of
introducing augmented learning to photonics training. All public and
private institutions of vocational and higher education are invited to
participate in this project.
7 Acknowledgement
The authors want to tank the German Federal Ministry for Education and
Research as well as the state government of Saxony-Anhalt, who funded
and supported the work described in this paper.
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