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What is NetLab?

The Importance of Practical Experiments

Practical experiments are an essential component of any University electrical engineering program. They provide the opportunity for students to apply their theoretical knowledge about the behaviour of electrical systems to real world problems. It develops important analysis skills. Most importantly, while reading about the mathematics in textbooks and listening to the explanations in lectures provide important information, actually getting hands on experience with it and seeing it for themselves will always be the most effective way to reinforce the concepts in the students mind and help them to remember it and understand it.

In electrical engineering programs, practical experiments often focus on circuit analysis. This involves constructing circuits from basic components such as resistors, capacitors and inductors and applying an input voltage waveform using a function generator. A function generator is a laboratory instrument capable of generating different shaped waveforms such a sine waves, square waves etc. at adjustable frequencies and amplitudes. With an input signal applied, students can observe the circuit response waveform on an oscilloscope. A digital multimeter is also commonly used to measure voltages, currents and resistances.

Despite the importance of practical experiments, they are difficult and expensive for universities to provide. Since they are performed in a laboratory that contains expensive equipment, the students must be supervised which limits the time they have. This also requires a class with many groups performing the experiment at the same time, and thus many instruments are required to support each group. Laboratory experiments are also a serious problem for distance learning students who may not have access to the laboratory at all.

Circuit simulation software is a common alternative. While simulation is useful (and indeed does also form an important part of the curriculum) it is not an adequate substitution for a laboratory practical session. Simulation usually presents an idealised situation without many of the difficulties of the real world, such as noise and measurement accuracy, which are important considerations in the real world. Also modern simulation software often has complex user interfaces with many advanced options, but it lacks the 'feel' of a hands-on laboratory with traditional instruments.

The NetLab Remote Laboratory

NetLab was created to address these problems by providing access to a real laboratory remotely via the internet 24 hours a day, 7 days a week. The main goal was to create a laboratory experience that would allow students to perform these common experiments on any PC, and have it feel as close as possible to using a real laboratory. It is accessible from anywhere in the world and students can perform the experiments unsupervised at any time that suited them, and take as long as they want to do it.

NetLab presents a rich graphical user interface on the computer that looks just like the real instruments. The users operate them with the knobs and buttons in exactly the same way as the would with the real thing and see the measurements displayed on the instrument screens. The displays update in real time as the user adjusts the instruments, just like a real experiment.

It is important to emphasise that NetLab is not merely a simulation. The users are interacting with real instruments, and making real measurements, but are doing so remotely. When you click a button on an instrument in NetLab, the corresponding real instrument in the laboratory responds immediately in exactly the same way as if you had physically pressed the button on the front panel. The waveforms displayed on the NetLab oscilliscope are actual measured signals from the real circuit, displayed exactly as it appears on the real oscilloscope.

Circuit Builder

One of the difficulties with remote laboratories is the problem of connecting the circuit when the experimenter is not actually in the laboratory. NetLab solves this problem with an innovative feature we call Circuit Builder (shown right). Users can pick from a list of available components, drag and drop to arrange them and then wire them up using their mouse. With a click of a button, the circuit is configured in the laboratory exactly as specified by the user. Using the available components they are free to make any circuit they like. This is possible due our use of a switching matrix, which can connect the terminals of any set of components in any configuration we like.

Of course, to have complete freedom with the circuit configuration, the users need to be able to choose the values of the resistors, capacitors and inductors. Rather than provide a large number of components with different values, we provide a small set of variable components which allow the user to choose any value they like. The user interface for these components is in keeping with the NetLab style in that it looks like variable component boxes that you find in the engineering labs, with four knobs to adjust the values. These computer-controlled components were specially designed and built for NetLab as a student's final year project.

Collaboration

One of the key design goals of NetLab was to encourage collaboration among students. NetLab supports multiple users working together on the same experiment. Each user connects from their own computer. Typically each user connects from their own home, but they could work together even if distributed across the globe. A chat room is embedded in the client which allows them all to communicate.

Any of the users in a session are free to operate the instruments. When anyone makes a change to an instrument, it is immediately reflected in everyone else's display and a notification message is displayed in the log in the corner indicating who made the change. This gives all members of the group the opportunity to participate. Groups ensure they get time together by booking a session time on the website. Sessions are in one hour slots and currently we allow up to three students to share a session in any given timeslot.

Live Laboratory Camera

A high quality web camera with a very powerful zoon is mounted in the laboratory that allows the NetLab users to observe the real instruments in real time as they operate them. The camera has motors which the users can operate that allow to pan and tilt, zoom right in and read the real displays of each of the instruments, or zoom right out and see the whole laboratory set up. Users can compare what they see on their NetLab displays with what the real instruments are displaying and see that they are identical and watch as they respond immediately while they interact with them with NetLab. We find that the camera improves the NetLab experience by making it more enjoyable and reinforcing the fact that they truly are operating real instruments.

Web-Based Accounts and Booking

Anyone anywhere in the world is welcome to try NetLab. All you need is to register for an account. There is a registration form on this website which will create a user account for you automatically. Once you have an account, you can go to the booking page and book a timeslot. We allow each user to book up to 3 hours a week, though if they need more time they can submit a request to ask for more. The website also provides a way to edit your account details and to delete your account if you wish.

The website was a significant software development project in and of itself. It is developed and managed by the NetLab project students using modern web technologies and tools, with the user accounts and bookings stored in a relational database, all hosted on our own private server. Account details are stored securely with encrypted passwords. The website will be updated each year to include information about the new features being added to NetLab with each new final year project.