Reliable performance monitoring is indispensable for FM broadcast time service systems, yet systematic evaluation and long-term operational data in practical scenarios remain scarce. This study addresses the gap and verifies the actual service capability of the FM broadcast time service system deployed in 10 key Chinese cities. We established a systematic monitoring model, applied the GUM to evaluate measurement uncertainty, and conducted continuous, multi-site monitoring and statistical analysis over 24 months. Results show the expanded measurement uncertainty of all stations ranges from 62.768 μs to 80.646 μs (k = 2), meeting the 100 μs requirement, and long-term monitoring confirms the system achieves sub-millisecond timing accuracy in practical operation. This work fills the gap in long-term operational data for FM broadcast timing technology, provides a standardized uncertainty evaluation method for the monitoring system, and lays a robust theoretical and data foundation for the technology’s optimization and wide adoption, thereby enhancing user confidence in FM broadcast time services.
Gao et al. (Thu,) studied this question.