Demonstration of Measurement Method based on Under-sampling for mmWave Radio Communication Signals

The increasing frequencies and speed of radio communication signals require measurement instruments with faster sampling frequencies. On the other hand, such high-speed measurement instruments tend to lose accuracy. Therefore, we have proposed an evaluation system based on under-sampling for the purpose of measuring high-speed communication signals with high resolution. This paper presents the first demonstration experiments using a QPSK signal in the millimeter-wave band. In the experiments, the QPSK signal was demodulated under synchronous and asynchronous conditions. The demodulated baseband signals were measured by the proposed system using under-sampling. The measurement results showed good agreement, suggesting that the under-sampling measurement system can measure communication signals with frequency elements much higher than the sampling frequency.