Software-defined radio decoding of DCF77: Time and frequency dissemination with a sound card

We investigate time and frequency dissemination using software-defined radio processing of signals acquired from a low-frequency emitter using a sound card. We use the resulting propagation time measurements for investigating some ionosphere physics and its interaction with cosmic ray flux. Rather than using the amplitude of the transmitted signal as classically considered, we here focus on a precise time of flight measurement by demodulating the spectrum spreading phase modulation added to the DCF77 amplitude modulation.