Dual-Mixer Time-Difference Measurement system using discrete Fourier transformation

Simplified Dual-Mixer Time-Difference Measurement system is proposed using discrete Fourier transformation (DFT) where no sinusoidal-pulsed converter, nor zero-cross detector are necessary. The phase meter integrating the proposed method with a dead time needed to process the time difference was demonstrated with an high resolution of σ_y(t=1 s)=7×10^-14 and σ_y(t=10000 s)=1×10^-16. The expected truncation error due to the usage of DFT was in good agreement with the observed one. Moreover, the multi-phase meter for five oscillator was easily demonstrated where three corner hat measurement was executed, and Allan deviation of more stable oscillator that two other ones was observed at an averaging time of approximately less than 30 s.