Improving the Dynamic Range of Software-Defined Radio Receivers for Spectrum Monitoring

Software-Defined Radios are particularly suited to performing radio spectrum monitoring from unmanned aerial vehicles. This is thanks to their reduced size, wide bandwidth and advanced signal processing capabilities. But their task is made increasingly more difficult by the growing densification of the radio spectrum and the increasing presence of interfering signals. These modern high-bandwidth receivers suffer from limitations stemming from these interfering signals reaching the analog-to-digital converter. Beamforming and frequency filtering appear as efficient techniques to reduce the dynamic range of the incoming signal so as not to saturate the analog-to-digital converter. The current state of the art of both beamforming and frequency filtering is presented along with the performance and limitations pertinent to wideband spectrum monitoring. Other mainly digital techniques are also explored, offering some more specialized solutions to reduce spurious signals post-acquisition.