FEMTO-ST/Time & Frequency department, Besancon, France
About the Presenter
About the Presentation
"Software Defined Radio for Time & Frequency Metrology: Demonstration with GNU Radio"
Software Defined Radio (SDR) aims at replacing analog radiofrequency (RF) signal processing with digital implementation: following digitization of the analog signal as early as possible, all signal processing steps are implemented as software, benefiting from stability, flexibility and reconfigurability. In this tutorial we remind the audience of the basic architecture of SDR receivers and the requirements for time and frequency transfer or characterization. Basic concepts are demonstrated using the free, opensource framework GNU Radio  allowing not only to address signal processing methods on synthetic signals but most significantly real time processing of datastreams collected from various RF frontends. Development frameworks aimed at simplifying the FPGA/CPU co-design are introduced. The rich fields addressed using SDR hardware are illustrated with precise time of flight measurement (RADAR systems) and the general means of spectrum spreading for improving timing resolution, how digital implementations allow for correcting analog circuit imperfection (I,Q imbalance) and how this strategy is used in spaceborne RADARs and vector network analyzers, GNSS reception and spoofing/jamming mitigation by analyzing the raw radiofrequency signal characteristics and yet generating 1-PPS output whose characteristics is consistent with commercial off the shelf receivers, acoustic wave field mapping and scanning probe microscopy in general, concluding with passive RADAR for time-frequency (range-Doppler) target mapping and selection of available hardware.