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PRECISION - OUR BUSINESS.

Precise Time Measurement

Time & Frequency Services with GalileoOrganized by

DLR and Kayser-ThredeHerrsching, 5. + 6.12.2005


Presented by

Werner R. Lange

Lange-Electronic GmbHGernlindenGermany

www.lange-electronic.de


With the (absolutely neccessary) help of

Dr. Günther KramerDr. Wolfgang Klische

K+K GmbHBraunschweig

Germany


Precise Time Measurement

Compare• Several clocks,

represented bytheir frequenciesand 1 pps outputs

• Perhaps longerdistances betweenclocks

• Each running on itsown oscillator orGPS receiver


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


Continuous Monitoring

• What most people do is comparingone signal with another

• But:Why not measure all signalssimultaneously?



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


Synchronous Phase Reading and Phase Interpolation


Precision of the Phase Measurement


An Example for Continuous Monitoring


„Scrambling“ and Linearity



• We are working in the picosecondrange

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

• We are dealing with effectshappening within IC‘s!


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


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


Thank you!

Questions?

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

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