SDRs in Time and Frequency Metrology

What piece of equipment do an Ytterbium optical clock lab and an amateur radio operator’s station have in common? One likely candidate is the software-defined radio. Identical SDR hardware has found equal popularity among those making precision measurements and those trying to catch the rarest DX stations. I present several examples of time and frequency measurements using SDRs, and how those techniques relate to amateur radio use cases. After a few detours into ongoing work using SDRs at NIST, I show how SDR measurements can answer time and frequency questions related to HamSCI projects.