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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 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 • 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 • 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 • 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 • 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 • 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