June 15, 2019
June 15, 2019
October 19, 2019
Electrical and Computer
In the recent literature, Software Defined Radio (SDR) has been promoted as a powerful and low-cost approach to offering laboratory experiments in the field of analog and digital communications. Furthermore, using the freeware graphical software GNU Radio Companion (GRC), a wide variety of experiments can be easily and quickly assembled by students on the SDR hardware. The GRC software includes built-in instrumentation blocks that allow visualization of the signals at any point in the modulation and/or demodulation process, lending strong experimental observation to reinforce theoretical concepts. Certain SDR hardware platforms provide duplex processing, allowing implementation of both the transmitter and receiver, for short distances.
The advantages of an SDR/GRC approach to offering communication laboratory experimentation is well described; however, the specific implementation details are less well documented. While conceptually not overly difficult, there are many non-trivial pitfalls and obstacles that must be overcome to actualize such communication experimentation. The intent of this paper is to address this knowledge gap and provide clear implementation details for a turn-key laboratory in a first or second course in analog and digital communications. To do so, a series of communications experiments are described, including all processing at both the transmitter and the receiver (including timing considerations), the interface to external files, the RF interface, and beneficial points to observe signals in either the time or frequency domain, or as appropriate, constellation plots. The configuration of the GRC blocks are described along with complete GRC flow graph diagrams for each modulation format presented. In certain cases, configuration of performance measurements, such as Signal-to-Noise Ratio (SNR) or Bit-Error-Rate (BER) are included. Dealing with issues such as timing alignment are also discussed. Finally, the implementation of custom blocks to augment the GRC library are also described.
This paper includes an overview of the use of SDR/GRC in communication laboratory experimentation as well as a description of the recommended hardware and development environment. Some general remarks about the development of GRC flow graphs is then followed by a detailed discussion of transceiver implementation. Particular transceivers discussed include the analog modulation formats AM and FM and the digital modulation formats FSK, PSK and QAM. The paper concludes with recommendations for additional and more advanced communication experimentation.
Edgcombe, J. D., & Dunne, B. E. (2019, June), Implementation of Analog and Digital Communications Transceivers on SDR Platforms using GNU Radio Companion Paper presented at 2019 ASEE Annual Conference & Exposition , Tampa, Florida. 10.18260/1-2--32936
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