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Master Clock for IceCube: First Year Implementation. Gerald Przybylski October 5, 2004 Lawrence Berkeley National Laboratory. The Big Picture. GPS Clock. Passive Fanout. Temporary Counting House 1 GPS Clock 1 Passive Fanout 9 DOM Hubs. DOM Hub. DOM Hub. DOM Hub. DOM Hub. DOM Hub.
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Master Clock for IceCube:First Year Implementation Gerald Przybylski October 5, 2004 Lawrence Berkeley National Laboratory
The Big Picture GPS Clock Passive Fanout Temporary Counting House 1 GPS Clock 1 Passive Fanout 9 DOM Hubs DOM Hub DOM Hub DOM Hub DOM Hub DOM Hub DOM Hub DOM Hub DOM Hub DOM Hub 8 Tuned Fanout cables for phase matching 18 Identical 32ns Fanout cables 1 serial daisy chain cable MasterClock '05
Goal Strong requirement • 10 MHz Clock Delivered, in-phase, to all DOR cards, within fraction of a ns • Time-tick arrival to satisfy DOR FPGA firmware ‘set-up and hold’ requirements Weak requirement • Timely arrival of serial string, within 1ms MasterClock '05
GPS Technology • TrueTime absorbed by Symmetricom • Symmetricom part of Datum Inc. • Performance Similar to other units at pole • OCXO Option for better Allan Variance • 10 MHz, 1Hz (or 1pps) and Serial Time string MasterClock '05
Pulse and Timing Signals • Multiple RF/Pulse Outputs- Internal jumpers &- MUX outputs (control by front panel, or serial port)- Specialized (option) outputs • IceCube’s needs:- Three 10 MHz outputs (sine) Fixed outputs J3e, J3f, J7- Five 1 Pulse per Second (or 1 Hz) Mux selected outputs J4, J5, J6, J8, J9 • Phasing required = Tuned Cables for all outputs MasterClock '05
Passive Fanout • 1:2 and 1:3 Resistive Matching Networks • Simple, but effective • Economical • Trouble-free MasterClock '05
Time String • Similar (standard?) time string format • 1-second Burst format from printer port • Content options - Like TrueTime string ddd:hh:mm:ss:q - Optional data suppressed by mode control • <cr><lf> <1ms after 1pps (1Hz) rising edge • Firmware soon: Kalle, and John Jacobsen • Daisy-Chain fan-out cable required MasterClock '05
Status • GPS clocks Procured and Tested • Passive Fan-out Fabricated and Tested • Tuned BNC cables Fabricated and Tested • Identical LEMO Cables On Order • Shipment to Wisconsin Imminent MasterClock '05