Timing and Synchronization Timing and Synchronization @ NML@ NML

B. ChaseB. Chase

7/12/077/12/07

Time StandardsTime Standards

There are two natural time metrics at NMLThere are two natural time metrics at NML NIST time which we can receive via GPSNIST time which we can receive via GPS RF time based on the 1300 MHz Master RF time based on the 1300 MHz Master

Oscillator and a “start trigger”Oscillator and a “start trigger” There is one “unnatural” time-baseThere is one “unnatural” time-base

Power line based 60 HzPower line based 60 Hz Power line synchronization is needed to alias out Power line synchronization is needed to alias out

line harmonics in accelerator systems by beam line harmonics in accelerator systems by beam Variability in power line frequency breaks the NIST Variability in power line frequency breaks the NIST

and RF relationshipand RF relationship

Suggested Time MetricsSuggested Time Metrics

GPS time for non beam related samplingGPS time for non beam related sampling As good as 10ns accuracy and max resolution for As good as 10ns accuracy and max resolution for

SOME systems. As bad as 10 us for othersSOME systems. As bad as 10 us for others Record the time for each start trigger (T0)Record the time for each start trigger (T0)

RF time-base for the RF cycleRF time-base for the RF cycle Sub 100 fs accuracy and resolutionSub 100 fs accuracy and resolution This can be translated to seconds for non beam This can be translated to seconds for non beam

information (ie RF waveforms)information (ie RF waveforms) For beam data the bunch number is used as an indexFor beam data the bunch number is used as an index

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

Data CorrelationData Correlation

RequirementsRequirements An accurate meter stick clock latticeAn accurate meter stick clock lattice A time stamp model that supports the clock A time stamp model that supports the clock

lattice (hardware and software)lattice (hardware and software) Analysis software that supports the multiple Analysis software that supports the multiple

time base issue and will also support the time base issue and will also support the multiple clock rates used in data acquisitionmultiple clock rates used in data acquisition

Clock Source SynchronizationClock Source Synchronization

Various clocks used for DAQ and control Various clocks used for DAQ and control must be aligned at T0 (start of RF must be aligned at T0 (start of RF process) synchronous with 60 Hzprocess) synchronous with 60 Hz Master Oscillator RF@ 1300MHz,, Laser @ Master Oscillator RF@ 1300MHz,, Laser @

81.25MHz, Controls clk @ 9.027778MHz, 81.25MHz, Controls clk @ 9.027778MHz, beam @ 81.25/n MHz, other?beam @ 81.25/n MHz, other?

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

Sources of Clean RFSources of Clean RF

Master OscillatorMaster Oscillator Main source but is only at one locationMain source but is only at one location

RF Reference lineRF Reference line Mostly for LLRFMostly for LLRF Very limited use for VERY good reasonsVery limited use for VERY good reasons

Local OscillatorLocal Oscillator Mostly for LLRFMostly for LLRF Others can use for good reasonsOthers can use for good reasons

Control clock (9.02777MHz)Control clock (9.02777MHz) Can be used with PLL or as isCan be used with PLL or as is Guessing much higher jitterGuessing much higher jitter