Asynchronous to synchronous waveform conversion for high frequency microwave and optical signals without external triggering.

Proper synchronization between transmitter and receiver ports in time-domain measurements is of great importance. This study presents a novel synchronization method that can be applied to data acquired from dual single-shot samplers in real time, diverging from the conventional approach that utilizes a single-shot sampler with an external trigger to synchronize the input signal. Following synchronization algorithm, its effectiveness is validated through experimental testing using a time-dependent, narrow-band transient radar signal. The experiments on a 5-cm thick polyvinylchloride (PVC) sample demonstrated the reliability of the proposed method. The transient radar signal utilized in the experiments had a carrier frequency of approximately 10 GHz, while data acquisition was carried out with an independent external trigger using only a 2 MHz sinusoidal signal. Applying the synchronization technique to the measurement results yielded a complex relative dielectric permittivity of (2.55 ± 0.02) - (0.23 ± 0.01)j. Using this value to calculate the speed of light in the PVC sample, the thickness was determined to be 5.29 ± 0.13 cm. Further refinement of the effective angle enhanced measurement accuracy, ultimately yielding a thickness of 4.83 ± 0.11 cm and reducing the relative error from 5.8 to 3.4%.