Adaptive phase synchronization in distributed digital arrays

Self-synchronizing distributed arrays have been investigated for a number of sensor applications such as radar. This paper discusses several methods for phase synchronizing a distributed array so that coherent processing can be performed. One of the concepts involves transmission of a beacon that is used directly as the frequency reference. After a phase synchronization process is performed sequentially across the array, measured phase differences are obtained that can be used in the digital processing to compensate for hardware and propagation channel differences. The concept was demonstrated for a two element array using commercial hardware at 2.45 GHz. Leakage cancellation techniques were employed to achieve phase accuracies of approximately 20 degrees.