The rapid spreading of digital technology resulted in many changes also in broadcasting systems. In digital communication systems increased data transfer rates are achieved with a simultaneous reduction of the bandwidth required for data transmission. However, this improvement of spectral efficiency can only be achieved by modern digital modulation techniques. The rapid development experienced in digital transmission systems is partly due to the digital modulation technique known as IQ-modulation.
Due to the widespread usage of digital technology it is essential that engineering students acquire the knowledge. For this, however, good demonstration tools are needed that help students deepen their theoretical knowledge with measurements.
To illustrate the properties of QAM modulations a quadrature modulator was developed in the Rohde & Schwarz Reference laboratory which allows the direct examination of the quadrature signals both in base- and carrier band.
My task is to optimize the quadrature modulator: to carry out the changes and improvements required in the analog circuitry, and to write the software for the device in such a way as to make it capable of producing different types of digital modulations, and to allow the waveforms to be measured at the measuring points.