Abstract:

This article presents a development of a virtual system for generating and measuring real time signals. It has been used successfully in the distance learning of bachelor students from the Technical University of Sofia - Plovdiv branch in the discipline “Electronic Measuring Instruments and Primary Transducers”. A virtual functional generator equipped with two real output signals has been developed using an DAC-module, which is built in the computer. For that purpose, a built-in soundcard of the personal computer is being used. By using the soundcard RealTek ALC269 real signals are produced in the form of AC voltages, trough the audio jack of the soundcard. The generator is fully functional and it can form three different type of the output signals – sine, triangular and rectangular.

Virtual measurement tool has also been developed in order to measure the parameters of the produced by the virtual functional generator real time signals. It could be also used for other real time signals parameter measurement. This tool contains an oscilloscope and a spectrum analyser. In that way students can solve various tasks related to the study of the signals’ shape, measuring frequency, amplitude and observing the waveforms. Additionally, a noise can be added to the signal and some other tasks can be done too.

The accuracy of the measurement with the observation tool is checked with an additional oscilloscope model Siglent SDS1052DL 50MHz. The relative errors of the frequency and amplitude measurement produced by the developed tool are similar to these done with Siglent.

The spectrum analyser implemented in the measuring tool gives the opportunity to make a spectral analysis of the generated signals and allows the students to become familiar with that kind of the measurements.

The workability of the virtual functional generator and the virtual measurement tool has been proven by a lot of experiments. According to the results, we can conclude that both based on virtual instrument technology can meet the requirements of high-precision and stable low and medium frequency in many fields. Different types of frequencies, amplitudes and output waveforms produced by the developed virtual functional generator can be set through PC control panel and the parameters of the signals generated through the DAC-modules output could be measured using developed Measurement Tool.

Oscilloscopes are an integral tool for those designing, testing, or repairing electronic equipment. Their applicability is very wide in different industries, this means that the students from technical specialties should have a lot of knowledge about this tool. The same goes for the generator and the spectrum analyser. They are used in the fields of electronics, measurement systems and automotive electronics, also each school or university in these fields, can take the advantage and teach their students with it, with a progressive method, that doesn’t require separate equipment or laboratories, but everything can be thought and done from one room and one device. Therefore, this generating and measuring becomes very appropriate for distant learning purposes.

From an economical point of view, we have developed a tool that is functional, user friendly and relatively cheap compared to the overall market. It can be used easily in the real work place or classroom without any additional components, directly with the most common device, computer or in distance education.

Keywords:

Virtual generating and measuring tool, e-learning, oscilloscope, spectrum analyser, LabVIEW.