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general overview
- 1. ITSF 2009 ROME SYNCHRONISATIONSOURCES FOR TELECOMMUNICATION NETWORKS GENERAL OVERVIEW Hartmut Roth General Manager Symmetricom GmbH
- 2. PAGE 2 Overview What IsA Sync Source Global Navigation Satellite Systems Atomic Clocks Sync Source Performance in Perspective Next Generation Sync Sources Conclusions
- 3. PAGE 3 Attributes ofSync Sources Sync Sources are typically Primary Reference Clocks (PRC’s) and must: Provide a Stratum 1 reference signal to other clocks within a network. Serve as a master clock for a network, network section, office or network element. Accurate to 1 part in 1011 (1x10-11) or better with verification to Universal Coordinated Time (UTC). 1 10 100 1000 10000 100000 0.01 0.1 1 10 100 1000 10000 100000 1000000 10000000 Observation time (seconds) MTIE(nonoseconds) 10-11 slope
- 4. PAGE 4 ITU-T G.811/ G.803 PRC France UK Germany 1 Frame slip in 72 days Long term frequency accuracy better than 1 x 10-11 Phase discontinuity better than 1/8 UI (64ns at 2048 kHz) TNC Level 1 Level 2 Level 3 SEC SEC SEC
- 5. PAGE 5 Classic PRCper ITU-T G.811 3x PRS (< 10-11) SSU (ITU-T G.812) PRC ITU-T G.811 Cs1 Cs2 Cs3 Phase discontinuity better than 1/8 UI (64ns at 2048 kHz)
- 6. PAGE 6 Clock SourceOverview Cesium Rubidium GNSS Receivers GPS, Glonass, Galileo, Compass Loran C / eLoran Receivers Long Range Navigation System Vers.C 90 kHz- 110kHz Long wave Receiver DCF77(D), MFS (UK), WWVB (US) CDMA Receiver Primarily USA TDM (Frequency) NGN (Frequency & Time) Mobile BTS (Wimax/Cellular) DVA/DVB/DVH SF MBMS Power Utility Military 2048 kHz 2048 kbps 1pps 10 MHz IEEE 1588 (PTP) NTP DTI/UTI IRIG-B
- 7. PAGE 7 Overview What IsA Sync Source Global Navigation Satellite Systems Atomic Clocks Sync Source Performance in Perspective Next Generation Sync Sources Conclusions
- 8. PAGE 8 Global NavigationSatellite System GNSS GPS GLONASS GALILEO COMPASS (Beidou2) Country Satellites + Spare (Plan) 27 + 3 (1993) 21 + 3 (2012) 26 + 4 (201x) 30 + 5 GEO (2015) Satellites in Constellation 31 (2009) 19 (2009) 24 (2012) 3Y 2 (2009) 4 (2011) 2Y 18 (2013) 4Y 2(2009) 12 (2011) 2Y 30 (2015) 6Y Orbital height 20180 km 19100 km 23222 km 21500 km Orbital period 11:58 h 11:15 h 14.05 h 12:35 h System Control Military Military Civil Military Timing Services Yes Yes Yes Yes Clocks Cs, Rb Cs PHM, Rb Rb TimeScale TAI-19 UTC-3 hours TAI Time Offset transmission GGTO GPS/Galileo Time Offset GGTO GPS/Galileo Time Offset Open service / 95% 100 ns 100 ns 30ns 50ns Open service / 95% 28m 35m 50m RNSS Regional Navigation Satellite Systems: QZSS (Japan), IRNSS (India) and Beidou1 (China)
- 9. PAGE 10 GNSS Time& Frequency System Pro‘s: - low cost - high quality PRS, if stable internal Oscillator used - provides frequency, time and phase ! Con‘s: - off air system, need to receive satellite information - outdoor antenna installation required (may be expensive) - lightning issues / protection - system errors may cause large time offsets RAIM Receiver Autonomous Integrity Monitoring doesn’t prevent for all errors ! - Jamming Output Tune Comparator GNSS Rx GNSS T/F System
- 10. PAGE 11 Overview What IsA Sync Source Global Navigation Satellite Systems Atomic Clocks Sync Source Performance in Perspective Next Generation Sync Sources Conclusions
- 11. PAGE 12 Cesium atomicclock autonomous PRS Telecom Cs / ETSI / 12 years tube famous 5071A Cs 80% weight in UTC Pro‘s: - strategic independent, autonomous high quality PRS (x 10-12 ) - up and running within 30 minutes after power on - no external reference signals required - no antenna installations required - long life time tubes, warranty up to 12 years - Cesium beam no frequency aging behavior (Rb, Maser age) - self controlled, alarm indication Con‘s: - expensive compared to GNSS Receiver - Cs beam tube needs to be replaced after 12 years typical - ToD outputs require initial time synchronization
- 12. PAGE 13 Rubidium AtomicClocks Almost a Primary Reference Source Use: - Versatile frequency source for many commercial, telecommunication & aerospace applications - first atomic clock in space - meets lifetime mobile basestation holdover - perfect Osc. inside GNSS & SSU systems Pro‘s: - small, light, low cost, low power atomic clock - fast warm up (7 minutes) - excellent retracibility - unlimited lifetime (physics doesn‘t limit lifetime) - self controlled, alarm indication - 3-6 weeks network holdover - very good short term stability Con‘s: - doesn‘t meet PRS stability specification - Rubidium typical frequency aging of 1 to 5e-11/month - initial factory calibration / aging correction required
- 13. PAGE 14 Other AtomicClocks Active Hydrogen Maser (AHM) Uses intrinsic properties of the hydrogen atom. Best short term frequency stability Frequency stability is ~40X superior to cesium Relatively large, complex and expensive Used for maximum stability (Master Ground Stations for GNSS, National standards, radio ground stations, and very long baseline interferrometry). Passive Hydrogen Maser (PHM) Uses intrinsic properties of the hydrogen atom. The cavity is fed by an external 1420 MHz frequency (passive vs. active) that is tuned to produce the maximum output in the cavity. Frequency stability comparable to lower Cesium H2 replenishment after 4-6 years. Passive Maser show frequency aging behavior, therefore is not a good standalone PRS
- 14. PAGE 15 Overview What IsA Sync Source Global Navigation Satellite Systems Atomic Clocks Sync Source Performance in Perspective Next Generation Sync Sources Conclusions
- 15. PAGE 16 Oscillator Stabilityversus GPSAllanDeviation(rf/f)ADEV Observation period in seconds 30s 200s 1.5ks 30Ks 8h 500ks 6d
- 16. PAGE 17 GR-2830 GPS PRCstability with SA on / off
- 17. PAGE 19 Overview What IsA Sync Source Global Navigation Satellite Systems Atomic Clocks Sync Source Performance in Perspective Next Generation Sync Sources Conclusions
- 18. PAGE 20 NGN PRSSync Source SSU/PRS BITS Legacy Network Elements F F F F F Network Probe STB/Res G NTP Master ModuleNTP (Network Timing Protocol) RT Categories MSPP: Multi Service Provisioning Platform MSAN: Multi Service Access Node EAD: Ethernet Aggregation Device IP DSLAM PON Enterprise Building Wireless Base Station TDM Transport TDM Transport Ethernet Ethernet ClientMaster ModulePTP/ IEEE 1588 Sync Protocol (1G Sync E) PTP PTP ClientMaster ModuleG. UTI (Universal Timing Interface) Future Network Elements T&F T&F F
- 19. PAGE 21 Sync Sourcesin the NGN Network CORE Content Network VoD TV Mesh AGGREGATION ACCESS SUBSCRIBER xPON DOCSIS xDSL TDM/ ATM TDM/ ATM OLT M-CMTS 3GPP/2 Ethernet DSLAM WiMAX Mobile Residential Business Licensed/ un-licensed Self Build: Hub & Spoke or Ring Network Management SoftwareTimePictra TimeScan TimeMonitor SSU 2000 TDM signals NGN signals NTP & PTP Server TP 1100 w/NTP TP5000 PTP Master Clock TP 500 ext. PTP Client TP100 GPS Source TimeCesium PTP SoftClient Solutions Rb-OEM Source
- 20. PAGE 23 PTP clientsample field data – MTIE G.823 traffic 15 ppb G.823 1 ppb SymmTP500 PTP client Live deployed network in Europe Sync was tested over Packet-over-SDH, 2 weeks Moderately loaded network ring (7 hops in one direction, 15 hops in the other) Meeting G.823 sync mask + 1ppb with large margin
- 21. PAGE 24 Overview What IsA Sync Source Global Navigation Satellite Systems Atomic Clocks Sync Source Performance in Perspective Next Generation Sync Sources Conclusions
- 22. PAGE 25 Conclusions Cesium -Until mid 90s Cesium was the choice as PRS - Today Tier 1 and national operators use Cs as PRS for strategic / political reasons GPS - since beginning 90s continuously stable open service, the last years w/o SA - deregulated telecom market generated high demand on PRS’s, due cost reasons GPS disciplined PRS became very popular ! - By now the most deployed PRS in Telecom Networks ( at the beginning NO trust in GPS, today too much trust !!) GNSS - GPSIII, Glonass, Galileo, Compass provide many Satellites to choose from - new signals, more accuracy, integrity information, higher signal strength - interoperability Interoperable multi GNSS Receiver will become the ultimate PRS Sync Source Timing protocols like PTP will provide virtual sync sources throughout the IP NGN
- 23. PAGE 26 Thank YouFor Your Time … Symmetricom 2300 Orchard Parkway San Jose, California, 95131 United States of America [email protected] www.symmetricom.com Symmetricom GmbH Altlaufstrasse 25 85635 Höhenkirchen (Munich) Germany [email protected] www.symmetricom.com Hartmut Roth [email protected]