time & frequency services with galileo organized by dlr ... fileprecision - our business....

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Precise Time Measurement

Time & Frequency Services with GalileoOrganized by

DLR and Kayser-ThredeHerrsching, 5. + 6.12.2005

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Presented by

Werner R. Lange

Lange-Electronic GmbHGernlindenGermany

www.lange-electronic.de

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With the (absolutely neccessary) help of

Dr. Günther KramerDr. Wolfgang Klische

K+K GmbHBraunschweig

Germany

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Precise Time Measurement

Compare• Several clocks,

represented bytheir frequenciesand 1 pps outputs

• Perhaps longerdistances betweenclocks

• Each running on itsown oscillator orGPS receiver

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Precise Time Measurement• Phases of 10 MHz• Phases or differences

of 1pps signals• Using an oscilloscope• Or phase meter• Or spectrum analyzer• Or ….

• ContinuousMonitoring

t: 75ns

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Continuous Monitoring

• What most people do is comparingone signal with another

• But:Why not measure all signalssimultaneously?

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Continuous Monitoring

Simultaneuous measuring of all signals include:

• data sampling rates up to 10 ksamples/s

• resolution of 12,5 ps• noise floor of less than 1 ps• independant of waveform and

frequency

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Synchronous Phase Reading and Phase Interpolation

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Precision of the Phase Measurement

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An Example for Continuous Monitoring

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„Scrambling“ and Linearity

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Continuous Monitoring

• We are working in the picosecondrange

• We may see unexpected (but well explainable!) behaviour

• We are dealing with effectshappening within IC‘s!

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Measurement Error/“Noise Floor“ of Phase Difference at 10 MHz

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Conclusion:

• There are tools to compare and evaluatethe quality of clock ensembles

• Noise floor in the femtosecond range @ averaging times of single digit seconds

• Independant of the clocks frequencies• Low temperature sensitivity of +-1ps/°K

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Thank you!

Questions?