Low Cost Vector Signal Analyzer For Communication Experiments

Vector signal analyzers (VSA) are systems that provide real-time analysis of in-phase and quadrature components of RF signals, as well as providing spectral analysis and other signal measurement features. VSA’s would be an ideal addition to any undergraduate communications laboratory because of their ability to investigate the many types of signals prevalent today. Unfortunately, most VSA’s are priced well beyond the budgets of typical undergraduate ECE departments. This paper describes a novel low-cost VSA that uses basic PC data acquisition (DAQ) cards to capture signals of interest and real-time processing of signals with LabVIEW and MATLAB. This VSA system provides a user interface that has much of the basic functionality of standard hardware VSAs, but with the limitation that bandwidth is constrained by the sampling rate of the DAQ. The system provides real-time plots of I/Q constellations. We describe the user interface as well as example laboratory experiments, where students get handson experience with a variety of signals such as BPSK, QPSK, and QAM. Any undergraduate lab with workbenches outfitted with standard PC and data acquisition equipment will be able to make use of this novel VSA.