Nicolet Instrument Corporation

Gregory J Berchin

A data acquisition system includes an analog to digital converter, a computer processor and a waveform memory in which is stored digital data from the A to D converter corresponding to an input signal. The processor provides a trigger responsive to a characteristic of a frequency component or components of the input signal to cause the memory to save the waveform data in the memory. The frequency characteristic may be determined, for example, by carrying out a synchronized recursive discrete Fourier transform which is updated for the selected frequency component or components with each new sample from the A to D converter.

Method and apparatus for frequency triggering in digital oscilloscopes

A data acquisition system such as a digital oscilloscope includes a central processing unit which controls the waveform memory, analog to digital converter, trigger generator, and display to automatically adjust the acquisition parameters to optimal values for a particular repetitive waveform received by the data acquisition system. The system initially optimizes the acquisition parameters for determining the length of the input waveform and then determines the input waveform length. Parameters are then determined for best frequency analysis of the input waveform, and the waveform is then frequency analyzed to determine its spectral content. Based on this information, the acquisition parameters are adjusted such that the sampling rate is sufficient to avoid aliasing of the highest significant frequency components of the input waveform while accommodating all or substantially all of the waveform within the memory capacity of the waveform memory, and the voltage range of the analog to digital converter is set so that the range of the input signal will substantially match the input range of the converter.

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Glen Ellyn, IL, United States of America

Gregory J Berchin