Electronic solid state circuitry controlled by an SDK-85 microcomputer forms the basis of a digitally controlled Fourier synthesizer module. The hardware involved in this module is the major thrust of this particular research work. Ultimately, once properly machine programmed, the microcomputer will control the base frequency, the number of harmonics present in the output waveshape, and the relative amplitudes and phases of these harmonics.The first phase of the hardware interface entails the conversion of square waves (from 8253 timers via the microcomputer) to triangle waveforms (via LM741 integrators). The triangle waves are then sine shaped by special clipping circuitry. It is the resultant sine waves that are then digitally controlled by machine software. The first stage of the above process eliminates the problem of frequency dependence and gain dropoff of the LM741 operational amplifiers. The relative amplitude of the triangle wave output of the LM741 is compensated for such that the sine shaping circuitry receives a constant amplitude waveform. The second phase of the hardware interface uses digital control of the final sine waveform by means of a Voltage Controlled Amplifier (VCA) and a Digital to Analog Converter (DAC). The VCA acts as the actual interface between the computer and the module.Finally, the output of the VCA'a are mixed and sent through an audio amplifier or to an oscilloscope for user inspection.
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/182433 |
| Date | January 1981 |
| Creators | Toscano, Ralph A. |
| Contributors | Thomas, Gerald P. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | vii, 104 leaves : ill. ; 28 cm. |
| Source | Virtual Press |
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