Advanced Oscilloscope Triggering Based on Signal Frequency

This paper presents a novel frequency based technique for triggering of the oscilloscope. Fast Fourier Transform (FFT) has the capability of analyzing waveforms in the frequency domain and this has opened up a new set of opportunities in digital oscilloscopes. The proposed FFT based technique can provide stable triggering even in the case of complex periodic signals. In this technique, the frequency of all harmonics present in the test signal is retrieved using FFT and the base repetition rate of the signal is found by selecting the frequency of the lowest harmonic present. This base frequency signal can be used to trigger the oscilloscope to obtain a stable waveform display. The efficacy of the method is evaluated by implementing the technique using DAQ (Data Acquisition) card and Lab VIEW ® software. Robustness of the technique is evaluated by simulated addition of random noise. It is found that the proposed technique is quite effective in detecting the base repetition rate of complex as well as simple waveforms and is quite robust. [PUBLICATION ABSTRACT]