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IceCube < - > AMANDA Clock Integration: Keeping Time

IceCube < - > AMANDA Clock Integration: Keeping Time. Lawrence Berkeley National Laboratory Gerald Przybylski March 21, 2005 IceCube Collaboration Meeting. The Goal. Synchronizing IceCube and AMANDA events to 10ns or better (do we all agree 10ns is a good goal)

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IceCube < - > AMANDA Clock Integration: Keeping Time

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  1. IceCube <-> AMANDA Clock Integration:Keeping Time Lawrence Berkeley National Laboratory Gerald Przybylski March 21, 2005IceCube Collaboration Meeting

  2. The Goal • Synchronizing IceCube and AMANDA events to 10ns or better(do we all agree 10ns is a good goal) • Retain a strategy for recovery from fault • As Simple As Possible • Robust

  3. Multiple GPS Clock Limitation • Spec: +/- 150 ns WRT UT (40ns RMS)- Propagation path variations- Signal Reflections- Satellite clock fluctuations- Constellation variations across multiple clocks => won’t make 10ns ‘requirement’

  4. Signal Distribution • From (permanent) ICH, Send 10 Mhz, 1 Hz (or 1pps), and Serial String • In MAPO, Regenerate TTL 10 MHz, 1 Hz, and RS-232 Serial in MAPO (GPS clock equivalent)

  5. Distribution paradigm features: • Signals from IceCube look like signals from a local GPS clock => easy switch over to local back-up GPS clock in case of outage in ICH. • Easy to understand and debug. • Fixed time offset between MAPO and IceCube counting house => constant in analysis software (the time offset of AMANDA hits not free fit parameter)

  6. MAPO-to-IceCube • AMANDA sends a trigger system signal (which it also time-stamps locally) to IceCube • IceCube triggers on and time-stamps the AMANDA signal with a DOM MB - Ref signal fed into a PMT signal input

  7. Feedback Features • By itself, adequate for merging events- Interpolate time corrections between time events • Constitutes a Check on distribution system functionality and stability • Provide drift compensation data arising from temperature coefficient of fiber

  8. DGPS? • Differential GPS can provide millimeter position resolution… Can DGPS provide nanosecond clock correlation between multiple GPS clocks at pole? • Used extensively in surveying, construction, road building… • Requires ‘base station’ with accurately known position (but pole station ice moves) • We’d require no custom time distribution hardware; no fibers needed, optical drivers, demodulators • 100% off the shelf hardware

  9. DGPS Unknowns: • Is a DGPS solution even feasible?- No. There is no commercial system that does the corrections on the fly. • Will different brand/model GPS receivers be required?- 15ns RMS seems to be the best you can do for phase error correcting GPS clocks. • Will there be any objection to placing a DGPS beacon? (it’s a radio source)- Moot point • Will DGPS be too costly?- Moot point

  10. Action items • Specify distribution hardware; Start building**Miteq – SLL - 0.005-3GHz Link - $2600 per Tx/Rx Pair*Fiber Span - AC300 - 0.1-2.2GHz Link - $2700 per Tx/Rx?Fiber-Span - AC102 - 5-500MHz Link -$?Is there a product for DC to 500 MHz? 3/27/05 still looking *Some evaluation done by RICE collaboration** Adopted by RICE

  11. Additional action items: • Confirm installed fibers-BK thinks they are already installed-Darryn probably knows whether they are installed+ Christian Spiring confirmed12 multi-mode + many single-mode • Confirm that 1 Hz (or 1PPS) isn’t too slow for fiber-Typical fiber link 50 KHz and up: Modulated? • Confirm that 9600 baud 8N1 isn’t too slow for fiber-Typical fiber link 50 KHz and up: IRIG- B better than serial overcoming fiber link frequency limitation

  12. Commercial Fiber Distribution Products • Symmetricom- Model 6530A and 6531A Carrier Only, no 1pps, no serial, no IRIG • Timing Solutions Corp-Model UTCG and TCT 10 MHz, 1PPS, Serial, IRIG-B, <5ns error, 200ps jitter-Acceptable MTBF numbers-<$13000 including both ends-Track record with NASA Deep Space Network-Long commitment to this product line

  13. UTCG + TCT solution IceCube Counting House MAPO Not relevant Symmetricom ET6000 UTCG 10 MHz + 1 PPS + IRIG-B AMANDA DAQ Local GPS clock Backup Components of sketch borrowed from Timing Solutions model 4300 manual LBNL GTP 5/28/05

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