The Time-Frequency Domain AnalysisOnline Laboratory Utilizing the EMONA DATEx
University: Makerere University
Team Member(s): Arthur Tumusiime Asiimwe
Faculty Advisors: CosmasMwikirize, Paul Isaac Musasizi, S.S. Tickodri-Togboa and Alfred. Mwambela
Title:Integrating the Frequency DomainFunctionality of the EMONA DATEx into the iLabs Shared Architecture
The developed online laboratory provides an interface where fourinstruments (Function Generator, Oscilloscope, Variable power Supply and theDynamic Signal Analyzer) can be used to analyze the circuit under test. Theuser is able to observe, in real time, the effect of changing variousparameters of the message signal and the carrier signal to achieve the desiredmodulation. The results are displayed in both the time and frequency domainsand the user is able to vary the Dynamic Signal Analyzer settings, to get thedesired output. Once integrated into curricula, the developed online platformshall supplement the conventional Laboratories where the requisite infrastructurehas been established.
Laboratory VirtualInstrumentation Engineering Workbench (LabVIEW)
National Instruments Educational Laboratory Virtual InstrumentationSuite (NI ELVIS II+)
EMONA Digital AnalogTelecommunications Experimenter (DATEx)
It is important to note that ofthe twelve instruments that are listed on the NI ELVIS mx Instrument launchershown in Figure 1, the DSA does not have an express VI that can be used toconfigure it in LabVIEW as illustrated in Figure 2.
A software equivalent of the DSAwas developed basing on the NI ELVISmx Dynamic Signal Analyzer Soft Front Panelshown in Figure 3 and the block diagram is shown in Figure 4. The DSA basicallyimplements the Fast Fourier Transform on the time signal and gives a plot ofthe RMS averaged Power Spectrum / Power Spectral Density (PSD) against frequencyof a single channel. Ofparamount importance is the FFT settings and Averaging section of the DynamicSignal Analyzer soft front panel. This enables the user to customize the FFTand averaging performed on the acquired data. The Frequency Span specifiesthe measurement range that starts at DC and extends to the Frequency Spanvalue. Resolution (lines) determines the length of the time-domain record andthe number of samples to be acquired. The user specifies the time-domain windowto use using the Window drop down menu. Customization of the display graph isachieved by the Frequency Display and Scale Settings section of the DynamicSignal Analyzer. With these settings, the user can configure the displayedunits for the magnitude plot, the display mode and axis maximum and minimumvalues.
The NI ELVIS II+ platform is remotelycontrolled from computer; through LabVIEW therefore a VI custom made for theModulation experiments used in the iLabs Shared Architecture to support the Time-FrequencyDomain Analysis Online Laboratory Utilizing the EMONA DATEx. The NI ELVIS II+ /DATEx bundle shown in Figure3, enables remote access to the instruments which are commonly used in aCommunications Engineering laboratory (Function Generator, Variable Power Supply, oscilloscope and the DynamicSignal Analyzer). The EMONA DATExis an add-on board for the NI ELVIS™ platform that allows a broad range ofintroductory telecommunications experiments to be implemented. It also providesa hands-on learning environment for students to see the fundamental math andtheory of telecommunications implemented with real-world electrical signals.