Receiver Design of Radio-Controlled Clocks Based on the New WWVB Broadcast Format

The architecture and algorithms for the first all-digital radio-controlled clock receiver for the new WWVB broadcast format are proposed. To address the potentially low signal-to-noise ratio conditions and the relatively large frequency offsets experienced in the receiver, two alternative timing synchronization approaches are investigated, i.e., one based on a maximum-likelihood (ML) criterion and the other based on correlation. We show that the correlation-based synchronization technique reduces the implementation complexity by over 50%, while its performance is only less than 1 dB inferior to that of the ML-based technique. Decision and detection algorithms are proposed for two operating regimes in the receiver: tracking and acquisition. In tracking, the proposed decision strategies reduce the timing mean squared error by as much as 63% compared with what the synchronizer produces without any additional processing. In acquisition, the proposed joint synchronization and decoding technique significantly improves the robustness by exploiting the channel code in the data. Compared with receivers based on the legacy broadcast, over 15 dB performance gains are achieved by the modulation and algorithms proposed for the tracking and acquisition operations. In addition to reception performance analyses, energy consumption tradeoffs are also presented.