1. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos Clock distribution and absolute time calibration in NEMO phase 1 Martino Ruppi INFN di Bari

2. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos Outlook NEMO phase 1 mini-tower Clock Requirements Clock Shore Station implementation Time data flow The console

3. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos NEMO phase 1 mini-tower FCM Symmetric systems offshore and onshore Dense Wavelength Division Multiplexing (DWDM) based on passive Add&Drop Synchronous Protocol FCM onshore  offshore Recovery clock offshore from data flow OM Front End (FE) and time- stamping in OM Analog signal sampled at fixed rate (200 MHz) Data recording triggered when signal exceeds a remotely-set threshold The clock recovered by FCM is sent to OM Synchronous Protocol FCM  OM 800 Mbps Synchronous protocol Junction Box DWDM Add&Drop Optical Module (OM & FE) Synchronous protocol Floor Control Module (FCM) 220 m 100 m 40 m

4. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos Clock Requirements Time counting in OMs is based on clock recovered in FCM  Each onshore FCM has to be synchronized by a low-jitter common clock We need to compare the OM time flow with UTC  Onshore clock has to be extracted from GPS clock and time information has to be sent to the apparatus System scaling to KM 3 size  The clock produced has to guarantee a very high fan-out

5. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos Clock Shore Station TDC 25ps sensitive GPS receiver (+/-30 ns RMS) GPS Antenna (now on the roof ot the onshore station) PC control Modular PXI Crate FPGA board National Instr. Recovery clock from GPS receiver Clock Fan-out toward FCMs onshore Data and time recovery by IRIG B format UTC data flow sent to FCMs onshore in synchronous protocol Go-and-Back time measurements with each pair of onshore/offshore FCM by TDC Network Time Protocol (NTP) server synchronization of PCs by ethernet GPS Receiver TDC Connecting Board Ck 10MHzIRIG B 4 X LVDS Ck 4MHz 4 X LVDS Time Data 4Mbit/s FPGA Stop x Start x RS232 GPS Antenna SCSI PC NTP

6. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos Data flow protocol to FCM 8b/10b code (reveling error, scrambling 0/1, byte function embedded) Time upgraded each 125  s Data (and Slow-Control) absolute time Acoustic data absolute time Room to accomodate more information or commands sec. 500 bit = 1/8000 seconds minhousdaysframes since 01/01/2006startIdle…stopsec since 01/01/2006Idle Data absolute timeAcoustic absolute time UTC

7. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos The Console (1) LabView enviroment FPGA Xilinx programming PC interface Instrument remote control Information storage in DB Logging Check alarms Accessible for control through ethernet

8. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos The Console (2) Off shore time calibration FPGA monitoring and management Go and Back time measurements TDC Management Satellite signal GPS locking On shore Time calibration

9. Martino Ruppi – KM3NeT 16 – 18 April 2007 - Pylos Conclusions The system is currently working in the NEMO Phase 1 control station Extension for a full-size 16-floor tower is undergoing (NEMO Phase 2) The setup can be easily adapted to serve even a KM3-size apparatus (it only needs more modules for the PXI crate)