Development of ADQ214 user interface in labVIEW.

University essay from Blekinge Tekniska Högskola/Sektionen för ingenjörsvetenskap; Blekinge Tekniska Högskola/Sektionen för ingenjörsvetenskap

Abstract: This thesis was conducted in collaboration with Signal Processing (SP) Devices Sweden AB. SP Devices provides digital signal processing solutions for the enhancement of analogue to digital conversion (ADC). Their ADCs facilitate the development of products for Communications, Radio base stations, Radar, Signals intelligence and Test & Measurement. The ADQ series digitizers, from SP Devices, are portable high performance digitizers which incorporate one or more analog inputs, an on-board double data rate (DDR2) memory and USB or PXI Express interface. DDR2 refers to the ability of a computer bus to transfer data on both the rising and falling edges of a clock signal. The ADCaptureLab software is a graphical user interface used to control this digitizer. ADCaptureLab, designed in the C/C++ programming language, is an easy-to-use standalone program which allows for configuration and operation of all ADQ series digitizers from SP Devices. The use of the LabView program from National Instruments forms the backbone of this thesis. LabVIEW (short for Laboratory Virtual Instrumentation Engineering Workbench) is a platform and development environment for a visual programming language from National Instruments. The topic of this thesis was to reproduce the ADCaptureLab user interface using LabView instead of C/C++. The graphical user interface (GUI) developed in LabView should be able to communicate with and control the processing of the ADQ214 digitizer (the digitizer model provided to us) in the same way as the ADCaptureLab. This would involve not only the data capturing and visualization but also digitizer configurations, monitoring of the device and ADQ functions and the analyses of acquired signal and FFT. In order to implement the configuration settings we developed functions for trigger settings (conditions at which a trigger will occur), Analogue Front End settings (AC/DC coupling), clock settings (sets the clock source), data type settings (set sample format), gain and offset setting (sets amplitude gain and mean value), pre-trigger settings (size of pre-trigger buffer), trigger hold off settings ( number of samples to wait for acquiring data after trigger), data acquisition length settings (Length of the acquired signal), continuous and single batch data acquisition, FFT transformation, save, load , and “clear plots” control (resets graph indicators). The functioning of our device may be monitored through the “Status window” (displays connection status of the ADQ device), “Devices window” (displays product information about the ADQ device), “Device monitor window” (returns the status of ADQ-API functions used) and the “Device information window” (returns information related to the revision of the ADQ device). Analyzing the acquired data and its corresponding FFT is made simple with the “Signal Properties” window (displays analyzed data), “Mark Harmonics” control (marks harmonics in the FFT) and the “Mark Signal Props” control (marks the fundamental tone and highest distortion in the FFT). Our LabVIEW GUI efficiently incorporates the features described above. In addition to being able to communicate instructions to the ADQ214 device we are able to monitor its condition and analyze any output. This result serves to show that it is possible to develop a program such as ADCaptureLab in LabVIEW.

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