Most Stable Raspberry Pi? 81% Better NTP with Thermal Management
a day ago
- #Precision Timing
- #NTP
- #Raspberry Pi
- The article discusses optimizing a Raspberry Pi-based NTP server for microsecond-accurate timekeeping using GPS PPS signals.
- Identifies thermal-induced timing jitter as a key issue, where CPU temperature changes affect the crystal oscillator's frequency stability.
- Proposes a two-part solution: CPU core isolation for timing-critical tasks and PID-controlled thermal stabilization to maintain constant CPU temperature.
- Details the implementation of a 'time burner' process that uses PID control to keep CPU temperature stable, indirectly stabilizing the oscillator's frequency.
- Reports significant improvements: 81% reduction in frequency variability and 49% reduction in RMS offset, achieving 38-nanosecond median RMS offset.
- Provides step-by-step setup instructions for replicating the optimized NTP server, including scripts for CPU core pinning and thermal stabilization.
- Discusses trade-offs, such as increased power consumption and CPU usage, and potential future improvements like adaptive PID tuning or using an OCXO.
- Concludes that while the optimization is unnecessary for most applications, it offers valuable insights into thermal management and precision timing.