Abstract:

Distance learning is becoming particularly up to date and is the only alternative in many areas of higher education in the context of COVID19 pandemics and lockdown. In engineering education, and in particular in the training of the telecommunications specialties, a significant problem is the remote conduct of the laboratory exercises. To acquire engineering knowledge, skills and competencies, students need to work with real measuring devices, studying various parameters of telecommunications equipment. This necessitates the in time development of systems for remote access to real engineering laboratories in the universities. That is why a team from Plovdiv University has developed laboratory exercises for distance learning on Fundamentals of Telecommunications. These exercises include new laboratory setups, a methodology for remote conduct of the exercises and a web-based interface for connection to a personal computer, which are part of a system for remote access to a telecommunications laboratory.

In this article we present the hardware part of the system for remote access to the Telecommunications Laboratory and the methodology for remote conduct of the exercises. A model for a remote laboratory system has been developed, which is a hardware module consisting of: two functional generators ADS9833, microprocessor board ARDUINO UNO, specialized operational amplifier LM13700, digital analog switches CD4016. By this module amplitude modulation, width-pulse modulation and pulse-code modulation can be realized and studied. When performing the laboratory exercises, the students have the opportunity to change different characteristics of of the carrier and modulating signal (frequency, amplitude, shape). A real GWInstek GSD-2000A oscilloscope is used to measure the output signals.

An opportunity for remote access to all modules of the laboratory system is provided, and for this purpose a specialized user software with WEB interface has been developed. The software is installed on a personal computer acting as a laboratory server and the communication between it and the model is realized through a USB interface. The Arduino Uno microprocessor board is an essential part of the hardware of the laboratory model. It is used for communication with the personal computer and for control of the individual electronic modules of the laboratory model.

ADS9833 digital generators are used to generate the carrier and the modulation signal. The change of the amplitude of the two signals is realized by a digital potentiometer MCP42010. The three integrated circuits are controlled by Arduino. For this purpose, they are connected on a common digital bus with a serial SPI interface.

The methodology for performing laboratory exercises in the discipline Fundamentals of Telecommunications includes the following three steps: simulation of the specific electronic circuit using an electronic simulator, study of the parameters of the circuit of the real laboratory model in the remote laboratory, comparison of simulation results and actual measurements. In this way, engineering students will be able to gain adequate knowledge from working with real models in the remote Telecommunications Laboratory.

Keywords:

Distance education, remote laboratory, web interface, Arduino.