Real Time Spectrum Sensing using SDR for RFI Analysis Mentees: Haozhong Guan, Kevin Minkue Kim PI: Lara Waldrop Mentors: Benjamin Eng, Gonzalo Cucho, Yamuna Phal Background Radio Frequency Interference (RFI) is a disturbance generated by an external source that affects an electrical circuit e.g (1) in wireless communication, intermittent connectivity loss, degraded performance or total stop in functioning (2) in radio astronomy, signal loss in Radar Back Scatter, received at the Arecibo observatory (AO) Objectives Capture example RF spectrum in the FM (97.5 MHz) and UHF (430 MHz) bands as initial processing step to find RFI Develop an instrument that measures signal power at a particular band Measure power content in RF Spectrum Understand the distribution of energy through time Figure 3: Spectrogram showing temporal variation Example Spectra - UHF Approach Figure 4: (a) Top plot : real component (Time Domain) (b) Mid Plot : imaginary component (Time Domain) (c) Bottom plot : FT (Frequency Domain) Figure 1: Block Diagram of SDR Features of RTL2832U Frequency Range: 24 - 1766 MHz USB 2.0 Interface Cost: $10 - $30 Required 3.3V external power Embedded with an advanced ADC(Analog - Digital Converter) Supported Software: Gqrx (Spectrum Viewer) Figure 5: Spectrogram showing temporal variation Example Spectra - FM Conclusions Developed successful initial prototypes of a highly diverse spectrum measurement device Demonstrated ability to track temporal changes in frequency spectrum Established a framework for RFI algorithm development Future Work Detect and remove unwanted RFI Develop visualization capabilities Put an algorithm to find power within a spectrum in Gqrx and implement this on SDR Figure 2: (a) Top plot : real component (Time Domain) (b) Mid Plot : imaginary component (Time Domain) (c) Bottom plot : FFT (Frequency Domain) Acknowledgements & References erence We would like to sincerely thank the mentors and PI for instructing this research and PURE committee for their help and support. A.C. Singer and D.C. Munson, Signal Processing of Discrete-time Signals Realtek company - RTL2832U Figures 2 and 4 (a)-(b) show the plot of the complex voltages received in time domain. Fourier Transform of the same signals is shown in (c). Based on the FFT plot, we can calculate the power of the signal. Figures 3 and 5 show the power variation over time.