Clock synchronization using servo-clock

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Method proposed for clock synchronization within distributed systems and networks

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Clock synchronization using servo-clock

  1. 1. Clock synchronization using servo-clock This work was developed within the scope of the Distributed Systems of MIEEC André Costa Lima Hugo Marques
  2. 2. Clock sync – importance Medium access control Synchronized sampling TDM
  3. 3. Clock sync – problem & solution Network nodes have their own clock • Clocks evolve at their own pace • There is no coherent notion of time • Clocks tend to diverge due to local driftPossible solution• Master node sends reference clock to slaves• Not perfect !! • Upon reception the reference is late • Network induced delay • Overheads
  4. 4. Estimating the network delayMeasuring Round-Trip delay(RTD)
  5. 5. Following the clock reference rate offset
  6. 6. Clock correction with Servo-ClockRate correctionSlave clock at time instant t error
  7. 7. Base experimental parametersClient-Server approach • Implementation in Java • TCP sockets • Clock server – master • Client – slave • Periodic clock reference requestClock generator Java Virtual Machine (JVM) high-resolution timer • System.nanoTime()
  8. 8. Slower and smoother correction
  9. 9. Unstable behavior
  10. 10. Faster convergence compensating offset errors
  11. 11. Conclusions

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