Timing and synchronization @ nml
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Timing and Synchronization @ NML. B. Chase 7/12/07. Time Standards. There are two natural time metrics at NML NIST time which we can receive via GPS RF time based on the 1300 MHz Master Oscillator and a “start trigger” There is one “unnatural” time-base Power line based 60 Hz

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Timing and Synchronization @ NML

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Timing and synchronization @ nml

Timing and Synchronization @ NML

B. Chase

7/12/07


Time standards

Time Standards

  • There are two natural time metrics at NML

    • NIST time which we can receive via GPS

    • RF time based on the 1300 MHz Master Oscillator and a “start trigger”

  • There is one “unnatural” time-base

    • Power line based 60 Hz

      • Power line synchronization is needed to alias out line harmonics in accelerator systems by beam

      • Variability in power line frequency breaks the NIST and RF relationship


Suggested time metrics

Suggested Time Metrics

  • GPS time for non beam related sampling

    • As good as 10ns accuracy and max resolution for SOME systems. As bad as 10 us for others

    • Record the time for each start trigger (T0)

  • RF time-base for the RF cycle

    • Sub 100 fs accuracy and resolution

    • This can be translated to seconds for non beam information (ie RF waveforms)

    • For beam data the bunch number is used as an index

  • Time, RF cycle# (event + delay), RF cycle#(bunch#)


Data correlation

Data Correlation

  • Requirements

    • An accurate meter stick clock lattice

    • A time stamp model that supports the clock lattice (hardware and software)

    • Analysis software that supports the multiple time base issue and will also support the multiple clock rates used in data acquisition


Clock source synchronization

Clock Source Synchronization

  • Various clocks used for DAQ and control must be aligned at T0 (start of RF process) synchronous with 60 Hz

    • Master Oscillator RF@ 1300MHz,, Laser @ 81.25MHz, Controls clk @ 9.027778MHz, beam @ 81.25/n MHz, other?

    • The LLRF LO @ 1313MHz will probably not be synchronized, LLRF clock @ LO/21


Sources of clean rf

Sources of Clean RF

  • Master Oscillator

    • Main source but is only at one location

  • RF Reference line

    • Mostly for LLRF

    • Very limited use for VERY good reasons

  • Local Oscillator

    • Mostly for LLRF

    • Others can use for good reasons

  • Control clock (9.02777MHz)

    • Can be used with PLL or as is

    • Guessing much higher jitter


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