Time and frequency corrections in a distributed radio network

In a distributed receiver system with independent analog-to-digital converters (ADCs), coherency between the ADCs can be difficult to achieve, but is often important for localization or tracking problems. A lack of coherency in receivers results in three main offsets: a sample timing offset, frequency offset, and phase offset that are introduced when the sampling begins. In this paper, an adaptive method for correcting these offsets using software feedback loops is presented. The system is implemented in GNU Radio with low-cost RTL-SDR receivers as a proof-of-concept.