Real-Time Wideband Spectrum Monitor Using Multiple Sampling Frequency Direct RF Undersampling for Wireless IoT
Takashi Shiba, Tomoyuki Furuichi, Kohei Akimoto, Mizuki Motoyoshi, Suguru Kameda, Noriharu Suematsu · 2021 51st European Microwave Conference (EuMC) · 2022
We show a compact, real-time and wideband spectrum monitor for wireless IoT by using multiple sampling frequency direct RF undersampling architecture. Simple AND process into spectrum expanded from multiple direct undersampling results is proposed for real-time performance which can be performed by commercial FPGA. We show a decision procedure of sampling frequencies and numbers of sampling points for wideband signals when AND process is used. We also use switchable frequency clock for one ADC in order to reduce the size of the monitor. We show time space margin between sampling interval for real-time performance in this case. We apply these techniques to a compact prototype spectrum monitor for wireless IoT band. A prototype equipment of 10 ms refreshing time, compact size ($280 \text{mm} \times 195 \text{mm} \times 45 \text{mm}$) and wideband spectrum performances are obtained. We succeed to observe three wireless IoT bands characteristics in real-time using a compact prototype spectrum monitor.