The COM4LAB courses in transmission and reception technology explain the setup of classic and modern radio systems as well as the modulation and demodulation of signals step by step. The characteristics of the signals are analysed in more detail in the time and frequency domains. The board contains a complete transmitter and receiver system. Components can be analysed individually.
The first course “Analogue Transmission Techniques AM, DSB, SSB and FM” deals with the superheterodyne architecture of transmitters and receivers as well as the basic analogue modulation types amplitude modulation (AM), double sideband modulation (DSB), single sideband modulation (ESB/SSB) and frequency/phase modulation (FM/PM).
Total duration: Up to 8 hours.
Target audiences
The course can be used to support the training process for the following professions, among others:
- Electrical professions in industry:
Electronics technician for industrial engineering
Electronics technician for automation technology
Electronics technician for devices and systems
Electronics technician for information and systems technology
Aircraft electronics technician
Mechatronics technician
- Electrical professions in the skilled trades:
Electronics technician specialising in automation and systems technology
Electronics technician for building systems integration
Information electronics technician
- IT professions:
IT systems electronics technician
IT specialist specialising in digital networking
IT specialist specialising in system integration
Learning objectives
The students should
- be able to receive radio signals in the VHF broadcasting range,
- be able to transmit radio signals with very low power in the VHF range,
- be able to identify the components of a transmitter and a receiver,
- understand how signals in the baseband are converted into the intermediate frequency range and the high frequency range by mixing,
- be able to measure and understand the parameters bandwidth, selectivity, far-field selection and near-field selection,
- experience which influences have an effect on the quality of a radio link and how these can be recognised,
- understand by measurement how amplitude modulated signals are generated and demodulated,
- understand by measurement how DSB and SSB signals are generated and demodulated,
- understand by measurement how FM and PM signals are generated and demodulated,
- understand what happens during an FFT (Fast Fourier Transform),
- understand why windowing is necessary for AD conversion and subsequent FFT and
- be able to distinguish between different window types by measurement.
Topics
The course will cover the following topics:
- receiving and transmitting radio signals in the FM range
- operation and function of transmitters based on the superheterodyne principle
- operation and function of receivers based on the superheterodyne principle
- functionality of mixers in combination with local oscillators (LO)
- filter structures
- amplitude modulation (AM)
- degree of modulation and bandwidth for AM
- double-sideband modulation (DSB)
- single-sideband modulation (SSB)
- generation of upper sideband (USB) and lower sideband (LSB)
- frequency modulation (FM) and phase modulation (PM)
- modulation index and bandwidth for FM
- bandwidth comparison between the modulation types
- demodulation of AM, DSB, SSB and FM signals
- task of amplifiers and filters
- functionality of a band-scanner as a spectrum analyser
- comparison of different windowings in the FFT
Previous knowledge
- Students need knowledge of the setup of electronic circuits in order to successfully complete the course.
- The use of formulae is a prerequisite.
- The basics of communications engineering must be known. The meaning of the terms amplitude, frequency and phase is assumed.
- It is important to distinguish between the frequency domain and the time domain of a signal. The mathematical basics of the continuous Fourier transform and the fast Fourier transform (FFT) are not assumed; the basics of the FFT are taught in the course.
- Knowledge of the exponential and logarithm laws is an advantage when converting power between watts and dBm/dB.
