======================================================================== = Information on NTP Time Servers and Radio Timecode Receivers = = This update 3 November 1994, last update 23 September 1994 = ======================================================================== Note: * indicates change since the previous version of this file. General Information This file is provided for information purposes only and represents the best information available at the date posted above. It does not represent a commitment to provide connectivity or time service on the part of the operators involved. Further information of a technical nature can be obtained from the ntp@ni.umd.edu list. To subscribe to this list, contact ntp-request@ni.umd.edu (Louie Mamakos). Alternatively, if possible, please subscribe to the newsgroup comp.protocols.time.ntp which is gatewayed to the mailing list. Send corrections or additions to mills@udel.edu (Dave Mills). Time Servers As the load on the hosts supporting NTP primary time (stratum 1) service is heavy and always increasing, clients should avoid using the primary servers whenever possible. In most cases the accuracy of the secondary servers is only slightly degraded relative to the primary servers and, as a group, the secondary servers may be just as reliable. As a general rule, a client should use a primary server only under the following conditions: 1. The server provides synchronization to a sizable population of clients on the order of 100 or more. 2. The server operates with at least two and preferably three other servers in a common synchronization subnet designed to provide reliable service even if some servers or the lines connecting them fail. 3. The administration(s) that operates the subnet coordinates other clients within the region in order to reduce the resources required outside that region. Note that at least some interregional resources are required in order to ensure reliable service. In order to ensure reliability, clients should spread their use over many different servers. As a general rule, no more than two clients per network should use the same server on another network; however, in order to simplify management of host configuration tables, many hosts on the same network may use the same (redundant) servers on the same network. Further information on client configuration can be found in the information files in the pub/ntp/doc directory and in the NTP distributions ntp.3.4 and xntp3 in the pub/ntp directory, both on louie.udel.edu. Unix users are strongly encouraged to adopt the latest NTP Version 3 software in the compressed tar distribution of xntp3.x.tar.Z in the pub/ntp directory on louie.udel.edu, where x designates the sub-version identifier, currently 4h. Besides providing more accurate, reliable service, this version automatically increases the polling intervals for all peer associations, but without sacrificing performance. This can significantly reduce network loads, as well as the loads on the busy primary servers, some of which have over 400 clients. Following is a list of NTP primary and secondary time servers known to be connected to the Internet and may be available for external access. Each entry gives the host name, Internet address, approximate location and geographic coordinates, if available, synchronization source (stratum, type of radio or satellite receiver and host type), suggested service area, access policy (as notified) and contact name and e-mail address. Those servers known to be running NTP Version 3 are indicated as well. It is always wise to consult the DNS to verify host addresses, which are changed from time to time. When more than one address is given, preference should given to each in order. All servers are equipped with uncompensated crystal-stabilized timebases, unless indicated otherwise. The contact person should always be notified upon establishment of regular operations with servers listed as open access. Please respect the access policy as stated by the contact person. Servers listed as closed access should NOT be used without prior permission, since this may disrupt ongoing research in which these servers are involved. Primary Servers --------------- apple.com (130.43.2.2) Location: Apple Computer, Cupertino, CA Synchronization: NTP primary (WWV clock), VAX/Unix Service area: NSFNET, BARR region, CSNET Access policy: open access Contact: Erik Fair (timekeeper@apple.com) bitsy.mit.edu (18.72.0.3) Location: MIT Information Systems, Cambridge, MA Geographic Coordinates: 42:21:36N, 71:05:24W Synchronization: NTP primary (WWV clock), VAX/Unix Service area: NSFNET, NEARnet area Access policy: open access Contact: Jeff Schiller (jis@mit.edu) canon.inria.fr (192.93.2.20) Location: INRIA, Rocquencourt (near Paris), France Synchronization: NTP V3 primary (TDF clock), Sun/Unix Service area: RENATER, France Access policy: open access, please send a message to notify Contact: ntp-adm@inria.fr Note: We use a Datel RCH208 clock with SER024 V24 interface. chantry.hawaii.net (128.171.1.1, 132.160.1.4) Location: University of Hawaii, Honolulu, HI Synchronization: NTP primary (WWV/H clock), Sun/Unix Service area: PACCOM region Contact: Kevin Mayeshiro (kevin@hawaii.edu) clepsydra.dec.com (16.1.0.22) Location: DEC Western Research Laboratory, Palo Alto, CA Synchronization: NTP V3 primary (GOES clock), Ultrix RISC Service area: NSFNET, BARR region Access policy: open access Contact: Jeff Mogul (mogul@decwrl.dec.com) or Paul A Vixie (vixie@vix.com) Note: The host name is an alias used only for time service. clock.llnl.gov (128.115.14.97) Location: Lawrence Livermore National Laboratory, Livermore, CA Synchronization: NTP V3 primary (WWVB clock), Sun 3/60 Service area: BARRNet, ESNet Access policy: open access Contact: Joe Carlson (carlson@lll-winken.llnl.gov) clock.nc.fukuoka-u.ac.jp (133.100.9.2) Location: Fukuoka university, Fukuoka, Japan Geographic Coodinates: 130:21.81E, 33:32.87N Synchronization: NTP V3.3 primary (GPS clock), Heliostation 400/SunOS 4.1.3 Service area: Japan/Pacific area Access policy: open access Contact: TSURUOKA Tomoaki (tsuruoka@fukuoka-u.ac.jp), YOSHIMURA Kenji (yosimura@tl.fukuoka-u.ac.jp) Note: We use a TRAK 8810 GPS STATION CLOCK and a Furuno Electric Co.'s GN-72 GPS receiver respectively. clock.tl.fukuoka-u.ac.jp (133.100.11.8) Location: Fukuoka university, Fukuoka, Japan Geographic Coodinates: 130:21.81E, 33:32.87N Synchronization: NTP V3.3 primary (GPS clock), Heliostation 400/SunOS 4.1.3 Service area: Japan/Pacific area Access policy: open access Contact: TSURUOKA Tomoaki (tsuruoka@fukuoka-u.ac.jp), YOSHIMURA Kenji (yosimura@tl.fukuoka-u.ac.jp) Note: We use a TRAK 8810 GPS STATION CLOCK and a Furuno Electric Co.'s GN-72 GPS receiver respectively. clock.osf.org (130.105.1.156) Location: Open Software Foundation, Boston, MA Synchronization: NTP primary (WWV clock), PMAX/Unix Service area: NSFNET, NEARnet region Access policy: open access Contact: Paul Groff (groff@osf.com) Note: prior permission to access required fuzzy.nta.no (128.39.1.149) Location: The Research Department of the Norwegian Telecommunications Administration (NTA-RD), Kjeller, Norway Synchronization: NTP primary, (NTP clock), Fuzzball (LORAN-C timebase) Service area: Norway Access policy: closed access; for use only by prior arrangement Contact: Terje Hammer (ham@tor.nta.no) lerc-dns.lerc.nasa.gov (128.156.1.43) Location: NASA Lewis Research Center, Cleveland, OH Synchronization: NTP Primary (WWVB clock), Sun/Unix Service Area: NSFNET, OARNET Access Policy: open access Contact: Joe Rossoll (yyjer@scivax.lerc.nasa.gov) mizbeaver.udel.edu (128.4.1.2) Location: University of Delaware, Newark, DE Geographic Coordinates: 39:40:48.425N, 75:45:02.392W (GPS WGS84) Synchronization: NTP V3 primary (GPS clock), Tymeserve 2000 LAN Time Server, SNTP (RFC-1361) service Service area: NSFNET, SURA region Access policy: experimental access only; service may be withdrawn without notice Contact: Dave Mills (mills@udel.edu) Note: This server does not implement the NTP control-message protocol * ncar.ucar.edu (192.52.106.6, 192.43.244.9) Location: NCAR Supercomputer Center, Boulder, CO Synchronization: NTP V3 primary (WWVB clock), Sun 4/690 Service area: NSFNET, WESTnet region Access policy: open access, please limit to two peer hosts per site Contact: Greg Woods (woods@ucar.edu) ncnoc.concert.net (192.101.21.1) Location: CONCERT Network NOC, Research Triangle Park, NC Synchronization: NTP V3 primary (WWVB clock), Netclock/2, Sun 4/65 Service area: CONCERT region Access Policy: CONCERT region, other use by prior arrangement Contact: Tim Seaver (tas@concert.net) norad.arc.nasa.gov (192.52.195.10, 128.102.16.10) Location: NASA Ames Research Center, Moffett Field, CA Synchronization: NTP primary (WWV clock), Sun/Unix Service area: NSFNET, BARR region, NASA NSN, DOE ESNET, DDN Access policy: open access Contact: Milo Medin (medin@nsipo.arc.nasa.gov) ntp.ml.csiro.au (192.67.12.101) Location: CSIRO Marine Laboratories, Hobart, Tasmania, Australia Geographic Coordinates: 42:53:14S, 147:20:18E Synchronisation: NTP V3 primary (Kinemetrics OM-DC Omega clock), SGI/Unix Service area: AARNet Access policy: open access, but please send a message to notify. Contact: Steve Clift (clift@ml.csiro.au) Note: ntp is an alias and the IP address may change; please use DNS. Caveat: The path to here may exhibit significant delay asymmetry. ntp.syd.dms.csiro.au (swifty.dap.csiro.au) 130.155.98.13 Location: National Measurements Laboratory, Sydney Australia. Geographic Coordinates: 33:46:58S 151:09:06E Syncronization: NTP V3, HP 5061B Cesium Beam Frequency Standard via Leitch CSD-5300 Master Clock System Driver Service area: AARNet Access policy: open access Contact: Mark Andrews (clockmaster@syd.dms.csiro.au) ntp0.ja.net (128.232.0.8) Location: University of Cambridge Computer Laboratory, UK Geographic Coordinates: 52:12:00N, 00:09:00E Synchronization: NTP V3 primary (MSF EES clock), Sun/Unix Service area: JIPS, UK, Europe Access policy: closed access, email address below. Contact: jips-nosc@nic.ja.net Note: This server is part of the centrally managed JIPS (approximately ac.uk) NTP network. Any requests for connections (internal or external to JIPS) should be emailed to the Contact address above. ntp0.nl.net (193.78.240.12) Location: NLnet, Amsterdam, The Netherlands Synchronization: NTP primary (DCF77), Sun/Unix SunOS 4.1.3 Service area: The Netherlands/Europe Access policy: open access Contact: beheer@nl.net ntp1.sony.com (198.93.3.1) Location: Sony San Jose, San Jose, CA Geographic Coordinates: 37:24:9.7N 121:55:55.8W (GPS) Synchronization: NTP V3 primary (GPS clock), PC/BSDI 1.1 Service area: NSFnet, BARRnet region Access policy: open access, please contact first Contact: Jerry Scharf (scharf@sony.com), Paul Vixie (vixie@vix.com) ntps1-0.uni-erlangen.de (131.188.1.40) Location: University Erlangen-Nuernberg, D-91058 Erlangen, FRG Geographic Coordinates: 49.573N 11.028E (from Meinberg GPS 166) Synchronization: NTP V3 primary (GPS receiver (<<1us)), Sun SS2/Unix SunOS 4.1.3 Service area: Germany/Europe Access policy: open access, pick one of ntps1-{0,1,2}.uni-erlangen.de Contact: Frank Kardel, Rainer Pruy (time@informatik.uni-erlangen.de) ntps1-1.rz.Uni-Osnabrueck.DE (131.173.17.11) Location: University of Osnabrueck, D-W4500 Osnabrueck, FRG Synchronization: NTP V3 primary (DCF77 clock), Sun/Unix Service area: Germany/Europe Access policy: open access Contact: Gerald Timmer (gtimmer@rz.Uni-Osnabrueck.DE) ntps1-1.uni-erlangen.de (131.188.1.45) Location: University Erlangen-Nuernberg, D-91058 Erlangen, FRG Geographic Coordinates: 49.573N 11.028E (from Meinberg GPS 166) Synchronization: NTP V3 primary (DCF77 PZF receiver (<50us)), Sun 4/690/SunOS 4.1.3 Service area: Germany/Europe Access policy: open access, pick one of ntps1-{0,1,2}.uni-erlangen.de Contact: Frank Kardel, Rainer Pruy (time@informatik.uni-erlangen.de) ntps1-2.uni-erlangen.de (131.188.1.31) Location: University Erlangen-Nuernberg, D-91058 Erlangen, FRG Geographic Coordinates: 49.573N 11.028E (from Meinberg GPS 166) Synchronization: NTP V3 primary (DCF77 PZF receiver (<50us)), Sun 4/490/SunOS 4.1.3 Service area: Germany/Europe Access policy: open access, pick one of ntps1-{0,1,2}.uni-erlangen.de Contact: Frank Kardel, Rainer Pruy (time@informatik.uni-erlangen.de) otc1.psu.edu (128.118.46.3) Location: Penn State University, University Park, PA Synchronization: NTP V3 primary (WWV clock), Sun/Unix Service area: NSFNET, PREPNET, JvNCnet Access policy: open access Contact: John Balogh (JohnBalogh@psu.edu) (no longer: jdb@ecl.psu.edu) pi.bellcore.com (128.96.60.5) Location: Bell Communications Research, Morristown NJ Synchronization: NTP primary (WWVB clock), DECstation/Ultrix Service area: JvNCnet Access policy: open access Contact: Dan Strick (timekeeper@bellcore.com) Note: Timekeeper announces intention to withdraw service. rackety.udel.edu (128.4.1.1) Location: University of Delaware, Newark, DE Geographic Coordinates: 39:40:48.425N, 75:45:02.392W (GPS WGS84) Synchronization: NTP V3 primary (GPS clock), Sun IPC/SunOS 4.1.1 Service area: NSFNET, SURA region Access policy: closed access, except for stratum-2 servers providing synchronization to local networks of ten or more hosts Contact: Dave Mills (mills@udel.edu) shorty.chpc.utexas.edu (129.116.3.5) Location: UT SYSTEM CHPC, Austin, TX Synchronization: NTP V3 primary (WWV clock), Sun IPC/SunOS 4.1.1 Service area: NSFNET, THENET region Access policy: open access Contact: William L. Jones (jones@chpc.utexas.edu) swisstime.ethz.ch (129.132.2.21) Location: Integrated Systems Laboratory, Swiss Fed. Inst. of Technology, CH 8092 Zurich, Switzerland Geographic Coordinates: 47:23N, 8:32E Synchronization: NTP primary (DCF77 clock), Sun-4/490/SunOS 4.1.3 Service area: Switzerland/Europe Access policy: open access, Please send e-mail message to notify that you are using us for time service, so that we can alert you about any interruptions of service, etc. Contact: Adam Feigin (time@swisstime.ethz.ch) Note: The host name is an alias used only for time service. tick.usask.ca (128.233.3.100) Location: University of Saskatchewan, Saskatoon, SK, Canada Geographic Coordinates: 52:08:01N, 106:38:11W Synchronization: NTP V3 Primary (GOES clock), VAX/Unix Service area: SASK#net, CA*net, Canada Access policy: open access, prior arrangment required Contact: Glenn Hollinger (glenn@herald.usask.ca) Note: priority to local regional sites Note: tick.usask.ca and tock.usask.ca share a single GOES receiver * tick.usno.navy.mil (192.5.41.40) Location: U.S. Naval Observatory, Washington, DC Geographic Coordinates: 38:55:14.01 77:03:58.03 (GPS WGS84) Synchronization: NTP V3 primary (USNO Master Clock 2, H-maser), HP9000/747i Service area: NSFNET Access Policy: open access Contact: Rich Schmidt (res@tuttle.usno.navy.mil) * time-A.timefreq.bldrdoc.gov (132.163.135.130) Location: National Institute of Standards and Technology, Boulder, Colorado Geographic Coordinates: 39:59:43.9N, 254:44:15.9E, +1649.9m (WGS 84) Synchronization: Direct 1 pps from Cesium Ensemble, DECstation/ULTRIX Service Area: NSFnet, WESTnet Access policy: open to stratum-2 servers and others by arrangement Contact: Judah Levine (jlevine@time.nist.gov), (303) 492-7785 * time.nist.gov (192.43.244.18) Location: National Center for Atmospheric Research, Boulder, Colorado Geographic Coordinates: 39:58:43.44N 254:43:32.5E +1840m (WGS 84) Synchronization: ACTS dial-up with NTP backup, DECstation/ULTRIX Service Area: NSFnet, WESTnet Access policy: open to stratum-2 servers and others by arrangement Contact: Judah levine (jlevine@time.nist.gov), (303) 492-7785 Time1.Stupi.SE (192.36.143.150) Location: Stupi AB, Stockholm, SWEDEN Synchronization: NTP V3 primary (Saphir Cesium Beam Standard/GPS), BSDI Unix Service area: SUnet, NORDUnet Access policy: open access Contact: Peter Lothberg (roll@Stupi.SE) time.service.uit.no Location: The EDB Centre, University of Tromsoe, Norway Synchronization: NTP V3 primary (GPS clock), HP-UX/Unix Service area: NORDUnet Access policy: semi-open access, prior arrangment required Contact: (timekeeper@uit.no) timer.unik.no (128.39.10.149) Location: UNIK (University Department at Kjeller), Kjeller, Norway Synchronization: NTP V3 primary, (NTP clock), Fuzzball (cecium timebase) Service area: Norway Access policy: open access Contact: Paal Spilling (paal@tor.nta.no) Note: This host presently not responding. tock.usask.ca (128.233.3.101) Location: University of Saskatchewan, Saskatoon, SK, Canada Geographic Coordinates: 52:08:01N, 106:38:11W Synchronization: NTP V3 Primary (GOES clock), VAX/Unix Service area: SASK#net, CA*net, Canada Access policy: open access, prior arrangment required Contact: Glenn Hollinger (glenn@herald.usask.ca) Note: priority to local regional sites Note: tick.usask.ca and tock.usask.ca share a single GOES receiver * tock.usno.navy.mil (192.5.41.41) Location: U.S. Naval Observatory, Washington, DC Geographic Coordinates: 38:55:14.01 77:03:58.03 (GPS WGS84) Synchronization: NTP V3 primary (USNO Master Clock 2, H-maser), HP9000/747i Service area: NSFNET Access Policy: open access Contact: Rich Schmidt (res@tuttle.usno.navy.mil) truechimer.cso.uiuc.edu (128.174.5.49) Location: University of Illinois, Champaign, IL Synchronization: NTP V3 primary (WWVB clock), IBM-RS6000/250 Service area: CICNET, NSFNET, NCSA region Access policy: closed access except for peers that meet the three conditions outlined in the "Time Servers" section of this file. State agreement with those conditions in notification message. All others may use the ntp-{0,1,2}.cso.uiuc.edu stratum 2 servers. Contact: Paul Pomes (p-pomes@uiuc.edu) Note: truechimer is a DNS CNAME. The host with the WWVB clock will always have the truechimer alias. umd1.umd.edu (128.8.10.1) Location: University of Maryland, College Park, MD Synchronization: NTP V3 primary (WWVB clock), Fuzzball Service area: NSFNET, SURA region Access policy: closed access, except for stratum-2 servers providing synchronization to local networks of ten or more hosts Contact: Michael Petry (petry@ni.umd.edu) vecrhc1.hpl.hp.com (15.255.60.3) Location: Hewlett-Packard Laboratorites, Bristol, UK Synchronization: NTP primary (MSF clock), HP/Unix Service area: HP corporate Access policy: closed access; for use only by prior arrangement Contact: Robert Cole (rhc@hplb.hp.com) wave.mbari.org (134.89.2.100) Location: Monterey Bay Aquarium Research Institute, Pacific Grove, CA Synchronization: NTP primary (WWV clock), HP/Unix Service area: NSFNET, BARR region Access policy: closed access; for use only by prior arrangement Contact: Pat Allen (timekeeper@mbari.org) wwvb.col.hp.com (15.255.240.16) Location: Hewlett Packard Co., Colorado Springs, CO Synchronization: NTP V3 primary (WWVB clock), HP-UX Service area: NSFNET, BARR region Access policy: semi-open access, prior arrangment required Contact: Bdale Garbee (bdale@col.hp.com) wwvb.isi.edu (128.9.2.129) Location: USC Information Sciences Institute, Marina del Rey, CA Geographic Coordinates: 33:58:49N, 118:26:20W (USGS map NAD27) Synchronization: NTP V3 primary (WWVB clock), Fuzzball Service area: NSFNET, Los Nettos region Access policy: open access Contact: Steve Casner (casner@isi.edu) wwvb.erg.sri.com (128.18.{3,4,5,6,200}.39) Location: SRI International, Menlo Park, CA Synchronization: NTP primary (WWVB clock) Sun/Unix Service area: NSFNET, BARR Region Access policy: open access Contact: Bryan McDonald (bigmac@erg.sri.com) Note: wwvb.erg.sri.com is a CNAME for (presently) sparkyfs.erg.sri.com wwvb.erg.sri.com (128.18.{4,100,110}.39) Location: SRI International, Menlo Park, CA Synchronization: NTP primary (WWVB clock) Sun/Unix Service area: NSFNET, BARRnet Region Access policy: open access Contact: clockmaster@erg.sri.com Note: wwvb.erg.sri.com is a CNAME for (presently) sparkyfs.erg.sri.com. clockmaster@erg.sri.com is currently aliased to John Ferguson (ferg@erg.sri.com) and Bryan McDonald (bigmac@erg.sri.com). Last update: 5/25/94. wwvb.sdd.hp.com (15.255.160.64) Location: Hewlett Packard Co., San Diego, CA Synchronization: NTP V3 primary (WWVB clock), HP-UX/Unix Service area: NSFNET, BARR region Access policy: semi-open access, prior arrangment required Contact: Ken Stone (timekeeper@sdd.hp.com) Note: Used for code development Secondary Servers ----------------- ashe.cs.tcd.ie (134.226.32.17) Location: Trinity College, Dublin, Ireland Synchronisation: NTP secondary (stratum 2), DEC5810 Service area: Ireland, UK Access policy: open access Contact: time@maths.tcd.ie Note: salmon.maths.tcd.ie (134.226.81.11), ashe.cs.tcd.ie (134.226.32.17) and lib1.tcd.ie (134.226.1.24)peer together over local area net, and one or more usually run at stratum 2. It is normally sufficient just to pick one machine to peer with. augean.eleceng.adelaide.edu.au (129.127.28.4) Location: University of Adelaide, South Australia Synchronization: NTP secondary (stratum 2), Sun-4/75/Unix Service area: AARNet Access policy: open access Access policy: open access, please send a message to notify Contact: Tarmo Rohtla (tarmo@eleceng.adelaide.edu.au) beowulf.ucsd.edu (132.239.51.6) Location: UCSD Computer Science & Engineering Department, San Diego, CA Synchronization: NTP secondary (stratum 2), Sun/Unix Service area: CERFNET; NSFNET, SDSC region Access policy: open access, please send a message to notify. Contact: timekeeper@cs.ucsd.edu bernina.ethz.ch (129.132.98.11) Location: Swiss Fed. Inst. of Technology, CH 8092 Zurich, Switzerland Geographic Coordinates: 47:23N, 8:32E Synchronization: NTP secondary (stratum 2), Sun SS10-51/SunOS4 Service area: Switzerland/Europe Access policy: open access Contact: Adam Feigin (time@iis.ee.ethz.ch) biofiz.mf.uni-lj.si (193.2.69.11) Location: Institute of Biophysics, University of Ljubljana, Slovenia Geographic Coordinates: 46:03:09N, 14:30:40E Synchronisation: NTP V3 secondary (stratum 2), HP/Unix Service Area: Slovenia/Europe Access policy: open access, please send a message to notify Contact: Primoz Peterlin (time@biofiz.mf.uni-lj.si) black-ice.cc.vt.edu (128.173.4.71) Location: Virginia Tech Computing Center, Blacksburg, VA, USA Synchronisation: NTP V3 secondary (Stratum 2), RS/6000-220 Service Area: southeastern US, anyplace netwise close to ANSNet Greensboro Access policy: open access Contact: valdis@black-ice.cc.vt.edu or Valdis.Kletnieks@vt.edu Note: ntp-2.vt.edu is a CNAME for black-ice.cc.vt.edu chime1.surfnet.nl (192.65.81.6) Location: SURFnet bv, Utrecht, The Netherlands Synchronisation: NTP secondary (Stratum 2), Sun Sparc Service area: The Netherlands Access policy: open access Contact: netmaster@surfnet.nl Note: Chime1.surfnet.nl is peering with chime2.surfnet.nl (192.87.36.2), which is located in Delft, The Netherlands. Please notify netmaster@surfnet.nl in case you will start chiming us, so we can put you on the email notification list, for outages, IP address changes, becoming a Stratum 1, etc.. churchy.udel.edu (128.4.1.5) Location: University of Delaware, Newark, DE Geographic Coordinates: 39:40:48.425N, 75:45:02.392W (GPS WGS84) Synchronization: NTP V3 secondary (stratum 2), cisco IGS 9.2 router Service area: NSFNET, SURA region Access policy: experimental access only; service may be withdrawn without notice Contact: Dave Mills (mills@udel.edu) clock.psu.edu (128.118.25.3) Location: Penn State University, University Park, PA Synchronization: NTP V3 secondary (stratum 2), Sun/Unix Service area: PREPNET, JvNCnet, PSC region Access policy: open access Contact: John Balogh (JohnBalogh@psu.edu) (no longer: jdb@ecl.psu.edu) clock.tricity.wsu.edu (192.31.216.5) Location: Washington State University Tri-Cities, Richland, Wa Synchronization: NTP secondary (stratum 2), DS5100/Unix Service area: NSFNET, NorthWestNet Access policy: open access Contact: postmaster@beta.tricity.wsu.edu) Note: clock.tricity.wsu.edu is a CNAME for meson.tricity.wsu.edu clock1.unc.edu (152.2.21.1) Location: University of North Carolina-Chapel Hill, Chapel Hill, NC Geographic Coordinates: 35:54N, 79:03W Synchronization: NTP secondary (stratum 2), Sun4/SunOS/xntpd (V3) Service area: CONCERT region Access policy: CONCERT region, others by prior arrangement Contact: Timekeeper NOTE: The default restriction on this host is "noserve". Hosts outside the service area must make prior arrangements to receive time service. clock-1.cs.cmu.edu (128.2.250.95) Location: Carnegie Mellon University Computer Science, Pittsburgh, PA Geographic Coordinates: 40:26:39N, 79:57:12W Synchronization: NTP V3 secondary (stratum 2), DECstation 5000- 120/Ultrix 4.2A Service area: PREPNET, PSC region Access policy: open access, but please send a message to notify. Contact: Rudy Nedved (ern+@cs.cmu.edu) Note: The host name is an alias used only for time service. clock-2.cs.cmu.edu (128.2.222.8) Location: Carnegie Mellon University Computer Science, Pittsburgh, PA Geographic Coordinates: 40:26:39N, 79:57:12W Synchronization: NTP V3 secondary (stratum 2), DECstation 5000- 120/Ultrix 4.2A Service area: PREPNET, PSC region Access policy: open access, but please send a message to notify. Contact: Rudy Nedved (ern+@cs.cmu.edu) Note: The host name is an alias used only for time service. constellation.ecn.uoknor.edu (129.15.22.8) Location: University of Oklahoma, Norman, Oklahoma, USA Synchronization: NTP secondary (stratum 2), Mac Quadra 700/A/UX 3.0 Service Area: Midnet Access policy: open access Contact: Robert Shull (rob@mailhost.ecn.uoknor.edu) cuckoo.nevada.edu (131.216.1.101) Location: University of Nevada System Computing Services, Las Vegas, NV Synchronization: NTP V3 secondary (stratum 2), DEC Alpha/Unix Service area: NevadaNet, NSFNET, SDSC region Access policy: open access, please send message to notify Contact: Systems Group Note: cuckoo.nevada.edu is a CNAME for alphabits.nevada.edu cyclonic.sw.stratus.com (134.111.10.64) Location: Stratus Computer, Marlboro, MA Synchronisation: NTP V3 secondary (stratum 2), Sun 4/490 Service area: NEARNET, NSFNET Access policy: open access, please send a message to notify. Contact: Jim Murray (timekeeper@stratus.com) Note: Please select one of (lectroid.sw.stratus.com, cyclonic.sw.stratus.com) to equalize the load. delphi.cs.ucla.edu (131.179.128.36) Location: UCLA Computer Science Department, Los Angeles, CA Geographic Coordinates: 34:04:08N, 118:26:31W Synchronization: NTP secondary (stratum 2), Sun/SunOS Service area: NSFNET, SDSC region Access policy: open access Contact: Chinson Yi (chinson@cs.ucla.edu) eagle.tamu.edu (128.194.3.93) Location: Texas A&M Academic Computing Services, College Station, TX Synchronization: NTP secondary (stratum 2, ver. 3), DECstation 5000- 133/Ultrix Service area: NSFNET, SESQUI region, THEnet Access policy: open access Contact: Bryan A. Ignatow, Academic Computing Services, ignatow@tamu.edu esavax.esa.lanl.gov (128.165.196.1) Location: Los Alamos National Laboratory - Los Alamos, NM Synchronization: NTP secondary (stratum 2), VAX 6320/VMS Service area: ESNET, TECHNET area Access policy: open access Contact: Jim A. Whitfill whitfill@lanl.gov fartein.ifi.uio.no (129.240.102.2) Location: University of Oslo, Norway Geographic Coordinates: 59:56:32N, 10:43:22E Synchronization: NTP secondary (stratum 2), VAXstation/Ultrix Service area: NORDUnet Access policy: open access Contact: Anders Ellefsrud, Ole Bjorn Hessen (timekeeper@ifi.uio.no) Note: Other stratum 2 servers in the Oslo area available on request fuzz.psc.edu (192.5.146.42) Location: PSC Supercomputer Center, Pittsburgh, PA Synchronization: NTP V3 secondary (stratum 2), Fuzzball Service area: NSFNET, PSC region Access policy: open access Contact: Eugene Hastings (hastings@morgul.psc.edu) fuzz.sura.net (192.80.214.42) Location: SURAnet, College Park, MD Synchronization: NTP V3 secondary (stratum 2), Fuzzball Service area: NSFNET, SURAnet region Access policy: closed access; please use ntp1.sura.net or ntp2.sura.net Contact: timekeeper@sura.net Note: formerly known as clock.umd.edu (192.41.177.92); fuzz.sura.net has a CNAME of clock.sura.net gazette.bcm.tmc.edu (128.249.2.2) Location: Baylor College of Medicine, Houston, Tx Synchronization: NTP secondary (stratum 2), Solbourne-OS/MP 4.0C Service area: NSFNET, SESQUI region Access policy: open access Contact: Stan Barber (sob@tmc.edu) * gilbreth.ecn.purdue.edu (128.46.129.93, 128.46.141.93, 128.46.147.93, 128.46.148.93, 128.46.171.93) Location: Purdue University Engineering Computer Network, West Lafayette, IN Synchronization: NTP V3 secondary (stratum 2), Sun SPARCserver 1000/Solaris 2.3 Service area: NSFNET, CICNET area Access policy: open access Contact: Dave Curry (davy@ecn.purdue.edu) * gus.ecn.purdue.edu (128.46.129.79, 128.46.147.79, 128.46.166.79) deleted * harbor.ecn.purdue.edu (128.46.128.76, 128.46.129.76, 128.46.154.76) Location: Purdue University Engineering Computer Network, West Lafayette, IN Synchronization: NTP V3 secondary (stratum 2), Sun-4/75+/Solaris 2.3 Service area: NSFNET, CICNET area Access policy: open access Contact: Dave Curry (davy@ecn.purdue.edu) heechee.esa.lanl.gov (128.165.196.2) Location: Los Alamos National Laboratory, Los Alamos, NM Synchronization: NTP secondary (stratum 2), VAXStation 4000-VLC VMS+Multinet Service area: ESNET, TECHNET area Access policy: open access Contact: Jim A. Whitfill whitfill@lanl.gov jane.jpl.nasa.gov (137.78.80.135) Location: Jet Propulsion Laboratory, Pasadena, CA, USA Synchronization: NTP secondary (stratum 2), Sun/SunOS 4.x Service area: Los Nettos region (Southern California), NASA NSN Access policy: open access, please observe service area Contact: Steve Groom (stevo@elroy.jpl.nasa.gov) kuhub.cc.ukans.edu (129.237.32.1) Location: Kansas University Computer Center, Lawrence, Kansas 66047, USA Geographic Coordinates: 39:56N, 95:14W Synchronization: NTP secondary (stratum 2), VAX 9210/VMS Service Area: Midnet, NSFnet Access policy: open access Contact: Craig Paul (paul@kuhub.cc.ukans.edu) lane.cc.ukans.edu (129.237.32.2) Location: Kansas University Computer Center, Lawrence, Kansas 66047, USA Geographic Coordinates: 39:56N, 95:14W Synchronization: NTP secondary (stratum 2), VAXstation 3100/VMS Service Area: Midnet, NSFnet Access policy: open access Contact: Craig Paul (paul@lane.cc.ukans.edu) larry.mcrcim.mcgill.edu (132.206.1.1) Location: McGill RCIM, Montreal, QC, Canada Synchronization: NTP secondary (stratum 2), VAX-11/750/4.3BSD Service area: CAnet, RISQ region Access policy: open access Contact: Mike Parker (mouse@larry.mcrcim.mcgill.edu) lectroid.sw.stratus.com (134.111.10.1) Location: Stratus Computer, Marlboro, MA Synchronisation: NTP V3 secondary (stratum 2), Sun Sparc 2 Service area: NEARNET, NSFNET Access policy: open access, please send a message to notify. Contact: Jim Murray (timekeeper@stratus.com) Note: Please select one of (lectroid.sw.stratus.com, cyclonic.sw.stratus.com) to equalize the load. lib1.tcd.ie (134.226.1.24) Location: Trinity College, Dublin, Ireland Synchronisation: NTP secondary (stratum 2), DEC5000/200 Service area: Ireland, UK Access policy: open access Contact: time@maths.tcd.ie Note: salmon.maths.tcd.ie (134.226.81.11), ashe.cs.tcd.ie (134.226.32.17) and lib1.tcd.ie (134.226.1.24)peer together over local area net, and one or more usually run at stratum 2. It is normally sufficient just to pick one machine to peer with. libra.rice.edu (128.42.1.64) Location: Rice University, Houston, TX Synchronization: NTP secondary (stratum 2), Fuzzball Service area: NSFNET, SESQUI region Access policy: open access Contact: Farrell Gerbode (gerbode@rice.edu) Note: this server has not been heard from for many months [dlm] nic.near.net (192.52.71.4) Location: Cambridge, MA Synchronization: NTP secondary (stratum 2), Sun/Unix Service area: NEARnet Access policy: open access Contact: NEARnet Operations (nearnet-ops@nic.near.net noc.near.net (192.52.71.21) Location: Cambridge, MA Synchronization: NTP secondary (stratum 2), Sun/Unix Service area: NEARnet Access policy: open access Contact: NEARnet Operations (nearnet-ops@nic.near.net ns.unet.umn.edu (128.101.101.101) Location: Minneapolis, MN Synchronization: NTP secondary (stratum 2), Sun/SunOS 4.1.3 Service area: CICNET region Access policy: open access, please send a message to notify. Contact: Networking Services, Paul Fakler (unet@unet.umn.edu) Note: select one of ns.unet.umn.edu or nss.unet.umn.edu to equalize load nss.unet.umn.edu (134.84.84.84) Location: St Paul, MN Synchronization: NTP secondary (stratum 2), Sun/SunOS 4.1.3 Service area: CICNET region Access policy: open access, please send a message to notify. Contact: Networking Services, Paul Fakler (unet@unet.umn.edu) Note: select one of ns.unet.umn.edu or nss.unet.umn.edu to equalize load ntp.css.gov (140.162.1.5) Location: Center for Seismic Studies, Arlington, VA Geographic Coordinates: 38:53:50N, 77:04:34W Synchronization: NTP V3 secondary (stratum 2), Sun-4/330, SunOS 4.1.3 Service area: NSFNET, SURA region Access policy: open access Contact: David Comay (dsc@seismo.css.gov) ntp.ctr.columbia.edu (128.59.64.60) Location: Columbia University Center for Telecommunications Research; New York City, NY Synchronization: NTP secondary (stratum 2), Sun/Unix Service area: PSINET; NSFNET, NYSER region Access policy: open access, authenticated NTP (DES/MD5) available Contact: Seth Robertson Note: IP addresses are subject to change; please use DNS ntp.olivetti.com (129.189.134.11, 129.189.134.6) Location: Olivetti ATC, Cupertino, CA Synchronization: NTP secondary (stratum 2), VAX/Unix Service area: Alternet Access policy: open access Contact: Jerry Aguirre (jerry@olivetti.com) ntp.univ-lyon1.fr (134.214.100.6) Location: CISM, Lyon, France Synchronization: NTP V3 secondary (stratum 2), Sun SS10 Service area: France, Switzerland, Italy, Europe Access policy: open access Contact: ntp-adm@univ-lyon1.fr Note: consult DNS to get host address, ntp is an alias. Note: we would appreciate getting a little note if you make regular use of this server, so that we can put you on our NTP mailing-list. * ntp0.pipex.net 158.43.128.1, 158.43.128.65 Configuration: NTP V3 secondary (stratum 2), Sun sparc 10, SunOS 4.1.3U1, xntpd 3.4d Location: Cambridge, UK Service area: PIPEX; UK Access policy: Semi-open access. These are primarily for use by PIPEX customers, but others in the UK are welcome to chime if they give notice. JANET users must apply through jips-nosc (see JANET entry for details). Contact: PIPEX support team (support@pipex.net) Notes: This is not currently a supported service of PIPEX, and is not subject to the 99.5% avilability guarantee. PIPEX customers should chime only to all three: ntp0.pipex.net, ntp1.pipex.net and ntp2.pipex.net. The master hosts, geographical location and operating systems are diversified to maximise reliability. Other users please chime to one of these three only. ntp0.strath.ac.uk (130.159.132.1, 130.159.144.62) ocation: Dept. Computer Science, Strathclyde University, Glasgow, Scotland. Geographic Coordinates: 04:14W, 55:52N Synchronisation: NTP V3 secondary Sun/Unix Service Area: UK/Europe/any Access policy: open access Contact: Jim Reid (ntp@cs.strath.ac.uk) Note: IP addresses are subject to change; please use DNS * ntp1.pipex.net 158.43.128.13 Configuration: NTP V3 secondary (stratum 2), Cisco 7000 router, 68040 processor, Version 10.2(1.2) Location: Cambridge, UK Service area: PIPEX; UK Access policy: Semi-open access. These are primarily for use by PIPEX customers, but others in the UK are welcome to chime if they give notice. JANET users must apply through jips-nosc (see JANET entry for details). Contact: PIPEX support team (support@pipex.net) Notes: This is not currently a supported service of PIPEX, and is not subject to the 99.5% avilability guarantee. PIPEX customers should chime only to all three: ntp0.pipex.net, ntp1.pipex.net and ntp2.pipex.net. The master hosts, geographical location and operating systems are diversified to maximise reliability. Other users please chime to one of these three only. ntp1.strath.ac.uk (130.159.132.66, 130.159.152.62) Location: Dept. Computer Science, Strathclyde University, Glasgow, Scotland. Geographic Coordinates: 04:14W, 55:52N Synchronisation: NTP V3 secondary Sun/Unix Service Area: UK/Europe/any Access policy: open access Contact: Jim Reid (ntp@cs.strath.ac.uk) Note: IP addresses are subject to change; please use DNS ntp1.sura.net (128.167.1.222) Location: SURAnet, College Park, MD Synchronization: NTP V3 secondary (stratum 2), Sun Sparc/SunOS Service area: SURAnet region Access policy: open access; please send a message to notify. Contact: timekeeper@sura.net * ntp2.pipex.net 158.43.192.13 Configuration: NTP V3 secondary (stratum 2), Cisco 7000 router, 68040 processor, Version 10.2(1.2) Location: London Docklands; at the Linx site - see http://www.linx.net/linx/linx.html Service area: PIPEX; UK Access policy: Semi-open access. These are primarily for use by PIPEX customers, but others in the UK are welcome to chime if they give notice. JANET users must apply through jips-nosc (see JANET entry for details). Contact: PIPEX support team (support@pipex.net) Notes: This is not currently a supported service of PIPEX, and is not subject to the 99.5% avilability guarantee. PIPEX customers should chime only to all three: ntp0.pipex.net, ntp1.pipex.net and ntp2.pipex.net. The master hosts, geographical location and operating systems are diversified to maximise reliability. Other users please chime to one of these three only. ntp2.strath.ac.uk (130.159.132.6, 130.159.132.65) Location: Dept. Computer Science, Strathclyde University, Glasgow, Scotland. Geographic Coordinates: 04:14W, 55:52N Synchronisation: NTP V3 secondary Sun/Unix Service Area: UK/Europe/any Access policy: open access Contact: Jim Reid (ntp@cs.strath.ac.uk) Note: IP addresses are subject to change; please use DNS ntp2.sura.net (128.167.254.198) Location: SURAnet, College Park, MD Synchronization: NTP V3 secondary (stratum 2), DEC DECstation/Ultrix Service area: SURAnet region Access policy: open access; please send a message to notify. Contact: timekeeper@sura.net ntp3.strath.ac.uk (130.159.196.126, 130.159.132.2) Location: Dept. Computer Science, Strathclyde University, Glasgow, Scotland. Geographic Coordinates: 04:14W, 55:52N Synchronisation: NTP V3 secondary Sun/Unix Service Area: UK/Europe/any Access policy: open access Contact: Jim Reid (ntp@cs.strath.ac.uk) Note: IP addresses are subject to change; please use DNS ntp4.strath.ac.uk (130.159.132.16, 130.159.132.124) Location: Dept. Computer Science, Strathclyde University, Glasgow, Scotland. Geographic Coordinates: 04:14W, 55:52N Synchronisation: NTP V3 secondary Sun/Unix Service Area: UK/Europe/any Access policy: open access Contact: Jim Reid (ntp@cs.strath.ac.uk) Note: IP addresses are subject to change; please use DNS ntp-1.mcs.anl.gov (140.221.10.70) Location: Argonne National Laboratory, near Chicago, IL Synchronization: NTP secondary (stratum 2), Sun Sparcstation 1 Service area: NSF/ANSNet, CICNet, NetIllinois, ESNet, others welcome Access policy: open access, please send a message to notify Contact: Bill Nickless (support@mcs.anl.gov) ntp-2.mcs.anl.gov (140.221.9.6, 140.221.10.64) Location: Argonne National Laboratory, near Chicago, IL Synchronization: NTP secondary (stratum 2), Sun Sparcstation 2 Service area: NSF/ANSNet, CICNet, NetIllinois, ESNet, others welcome Access policy: open access, please send a message to notify Contact: Bill Nickless (support@mcs.anl.gov) ntp0.cornell.edu (192.35.82.50) Location: Cornell University, Ithaca, NY Synchronization: NTP secondary (stratum 2), Sun/Unix Service area: NSFNET, NYSER region Access policy: open access Contact: Donald Redick ntp1.ossi.com (192.240.4.1) Location: Emeryville, CA Synchronization: NTP V3 secondary (stratum 2), Sun4-330/Unix Service area: BARRNet Access policy: open access, please send a message to notify. Contact: Mary Seabrook (mary@ossi.com) Note: select one of ntp1.ossi.com or ntp2.ossi.com to share load ntp2.ossi.com (192.240.4.50) Location: Emeryville, CA Synchronization: NTP V3 secondary (stratum 2), Sun4-690/Unix Service area: BARRNet Access policy: open access, please send a message to notify. Contact: Mary Seabrook (mary@ossi.com) Note: select one of ntp1.ossi.com or ntp2.ossi.com to share load louie.udel.edu (128.175.1.3) Location: University of Delaware, Newark, DE Synchronization: NTP V3 secondary (stratum 2), Vax-11/780/Unix Service area: NSFNET, SURA region Access policy: open access Contact: Dave Mills (mills@udel.edu) * molecule.ecn.purdue.edu (128.46.129.95, 128.46.132.95, 128.46.136.95, 128.46.145.95, 128.46.167.95, 128.46.169.95, 128.46.181.95) Location: Purdue University Engineering Computer Network, West Lafayette, IN Synchronization: NTP V3 secondary (stratum 2), Sun SPARCserver 1000/Solaris 2.3 Service area: NSFNET, CICNET area Access policy: open access Contact: Dave Curry (davy@ecn.purdue.edu) * molecules.ecn.purdue.edu (128.46.129.82, 128.46.132.82, 128.46.167.82) deleted ntp.cox.smu.edu (129.119.80.126) Location: Cox School of Business, Southern Methodist University, Dallas, TX Synchronization: NTP V3 secondary (stratum 2), DEC 3000/300LX AXP DEC OSF/1 AXP Service Area: NSFNET, SESQUI region Access policy: open access Contact: John Meaders (johnm@mail.cox.smu.edu) Note: Please send e-mail letting us know you will be using ntp.cox.smu.edu. ntp.cox.smu.edu is a CNAME for nyse.cox.smu.edu. ntp.adelaide.edu.au (129.127.40.3) Location: University of Adelaide, South Australia Synchronization: NTP V3 secondary (stratum 2), DECsystem 5000/25 Unix Service area: AARNet Access policy: open access Contact: Mark Prior (mrp@itd.adelaide.edu.au) ntp-0.cso.uiuc.edu (128.174.22.10) Location: University of Illinois, Champaign, IL Synchronization: NTP secondary (stratum 2), Cisco-ASM/4 Service area: CICNET, NSFNET, NCSA region Access policy: open access Contact: Paul Pomes (p-pomes@uiuc.edu) Note: select one of (ntp-0.cso.uiuc.edu, ntp-1.cso.uiuc.edu, ntp- 2.cso.uiuc.edu) to equalize load. Use names rather than IP addresses if possible. The ntp-N aliases follow wherever the service is moved to. ntp-1.cso.uiuc.edu (128.174.22.8) Location: University of Illinois, Champaign, IL Synchronization: NTP secondary (stratum 2), Cisco-ASM/4 Service area: CICNET, NSFNET, NCSA region Access policy: open access Contact: Paul Pomes (p-pomes@uiuc.edu) Note: select one of (ntp-0.cso.uiuc.edu, ntp-1.cso.uiuc.edu, ntp- 2.cso.uiuc.edu) to equalize load. Use names rather than IP addresses if possible. The ntp-N aliases follow wherever the service is moved to. ntp-2.cso.uiuc.edu (128.174.22.4) Location: University of Illinois, Champaign, IL Synchronization: NTP secondary (stratum 2), Cisco-ASM/4 Service area: CICNET, NSFNET, NCSA region Access policy: open access Contact: Paul Pomes (p-pomes@uiuc.edu) Note: select one of (ntp-0.cso.uiuc.edu, ntp-1.cso.uiuc.edu, ntp- 2.cso.uiuc.edu) to equalize load. Use names rather than IP addresses if possible. The ntp-N aliases follow wherever the service is moved to. Note: ntp-2 will be active after mid to late June. Rolex.PeachNet.EDU (131.144.4.22) Location: PeachNet NOC, Kennesaw, GA Synchronization: NTP secondary (stratum 2), Sun Sparc/Unix Service area: PeachNet (Georgia), SURAnet Access policy: open access, please send a message to notify. Contact: timekeeper@peachnet.edu Note: Please use the CNAME Rolex if at all possible, the IP might change one day. salmon.maths.tcd.ie (134.226.81.11) Location: Trinity College, Dublin, Ireland Synchronisation: NTP secondary (stratum 2), MIPS Magnum Service area: Ireland, UK Access policy: open access Contact: time@maths.tcd.ie Note: salmon.maths.tcd.ie (134.226.81.11), ashe.cs.tcd.ie (134.226.32.17) and lib1.tcd.ie (134.226.1.24)peer together over local area net, and one or more usually run at stratum 2. It is normally sufficient just to pick one machine to peer with. sundial.columbia.edu (128.59.40.142) Location: Morningside Campus, Columbia University, New York, NY Synchronization: NTP V3 secondary (stratum 2), Sun4/75 Service area: PSInet Access policy: open access Contact: Margarita Suarez tick.cs.unlv.edu (131.216.16.9) Location: UNLV Computer Science Department, Las Vegas, NV Synchronization: NTP V3 secondary (stratum 2), Mips/Unix Service area: NSFNET, SDSC region Access policy: open access Contact: Greg Wohletz Note: select one of (tick.cs.unlv.edu, tock.cs.unlv.edu) to equalize load Note: tick.cs.unlv.edu is a CNAME for (currently) elmore.cs.unlv.edu * ticktock.wang.com (150.124.136.4) Location: Wang Labs, Lowell MA, USA Synchronisation: NTP V3 secondary (stratum 2), '486 PC/BSDI 1.1 Service area: AlterNet, New England Access policy: Open access, please send mail to notify Contact: fitz@wang.com Note: ticktock is a CNAME timeserver.cs.umb.edu (158.121.104.2) Location: University of Massachusetts, Boston, MA Synchronization: NTP V3 secondary (stratum 2), DEC/Ultrix Service area: NEARNET, (and anyone else who would like it) Access policy: open access Primary Contact: John Rouillard (rouilj@cs.umb.edu) Secondary Contact: Rick Martin (rickm@cs.umb.edu) timex.cs.columbia.edu (128.59.16.20) Location: Columbia University Computer Science Department, New York City, NY Synchronization: NTP secondary (stratum 2), Sun/Unix Service area: PSINET; NSFNET, NYSER region Access policy: open access, authenticated NTP (DES/MD5) available Contact: James Tanis Note: IP addresses are subject to change; please use DNS Timex.PeachNet.EDU (131.144.4.21) Location: PeachNet NOC, Kennesaw, GA Synchronization: NTP secondary (stratum 2), Sun Sparc/Unix Service area: PeachNet (Georgia), SURAnet Access policy: open access, please send a message to notify. Contact: timekeeper@peachnet.edu Note: Please use the CNAME Timex if at all possible, the IP might change one day. tmc.edu (128.249.1.1) Location: Baylor College of Medicine, Houston, Tx Synchronization: NTP secondary (stratum 2), Sun/SunOS 4.1 Service area: NSFNET, SESQUI region Access policy: open access Contact: Stan Barber (sob@tmc.edu) tock.cs.unlv.edu (131.216.18.4) Location: UNLV Computer Science Department, Las Vegas, NV Synchronization: NTP V3 secondary (stratum 2), NeXT/Mach Service area: NSFNET, SDSC region Access policy: open access Contact: Greg Wohletz Note: select one of (tick.cs.unlv.edu, tock.cs.unlv.edu) to equalize load Note: tock.cs.unlv.edu is a CNAME for (currently) little- walter.cs.unlv.edu vtserf.cc.vt.edu (128.173.4.6) Location: Virginia Tech Computing Center, Blacksburg, VA, USA Synchronisation: NTP V 3 secondary (Stratum 2), DEC 5810/ultrix Service Area: southeastern US, anyplace netwise close to ANSNet Greensboro Access policy: open access Contact: valdis@black-ice.cc.vt.edu or Valdis.Kletnieks@vt.edu Note: ntp-1.vt.edu is a CNAME for vtserf.cc.vt.edu wuarchive.wustl.edu (128.252.135.4) Location: Washington University, St. Louis, Missouri, USA Synchronization: NTP secondary (stratum 2), DECstation 5000/Ultrix Service Area: Midnet Access policy: open access Contact: Chris Myers (chris@wupost.wustl.edu) * yoyo.aarnet.edu.au (129.127.12.4) Location: The University of Adelaide, Adelaide, South AUSTRALIA Synchronization: NTP secondary (stratum 2), DEC 3000/300L OSF/1 Service Area: AARNet Access policy: open access Contact: Mark Prior zeus.tamu.edu (128.194.3.85) Location: Texas A&M Academic Computing Services, College Station, TX Synchronization: NTP secondary (stratum 2, ver. 1), VAX 9000-210/VMS Service area: NSFNET, SESQUI region, THEnet Access policy: open access Contact: Bryan A. Ignatow, Academic Computing Services, ignatow@tamu.edu ======================================================================== Serial Timecode Formats Following are examples of the serial timecode formats used by the various manufacturers as given in the instruction manauals. These examples are intended only for illustration and not as the basis of system design. The following symbols are used to identify the timecode character that begins a subfield. The values given after this symbol represent the character offset from the beginning of the timecode string. C on-time character (start bit) T time of day D day of year or month/day A alarm indicator (format specific) Q quality indicator (format specific) In order to promote uniform behavior in the various implementations, it is useful to have a common interpretation of alarm conditions and signal quality. When the alarm indicator it on, the receiver is not operating correctly or has never synchronized to the broadcast signal. When the alarm indicator is off and the quality indicator is on, the receiver has synchronized to the broadcast signal, then lost the signal and is coasting on its internal oscillator. Spectracom 8170 and Netclock/2 WWV Synchonized Clock (format 0) "i ddd hh:mm:ss TZ=zz" C A D T poll: "T"; offsets: T = 7, D = 3, A = 0, Q = none i = synchronization flag (" " = in synch, "?" = out synch) ddd = day of year hh:mm:ss = hours, minutes, seconds zz = timezone offset (hours from UTC) note: alarm condition is indicated by other than " " at A, which occurs during initial synchronization and when received signal has been lost for about ten hours example: " 216 15:36:43 TZ=0" A D T Netclock/2 WWV Synchonized Clock (format 2) "iqyy ddd hh:mm:ss.fff ld" C AQD T poll: "T"; offsets: T = 9, D = 2, A = 0, Q = 1 i = synchronization flag (" " = in synch, "?" = out synch) q = quality indicator (" " = locked, "A"..."D" = unlocked) yy = year (as broadcast) ddd = day of year hh:mm:ss.fff = hours, minutes, seconds, milliseconds l = leap-second warning ("L" indicates leap at end of month) d = daylight time indicator (see manual) note: alarm condition is indicated by other than " " at A, which occurs during initial synchronization and when received signal has been lost for about ten hours; unlock condition is indicated by other than " " at Q example: " 216 15:36:43.640 D" AQ D T TrueTime 468-DC Satellite Synchronized Clock "<^a>ddd:hh:mm:ssq" D T QC poll: none; offsets: T = 4, D = 0, A = 12, Q = 12 hh:mm:ss = hours, minutes, seconds q = quality/alarm indicator (" " = locked, "?" = alarm) note: alarm condition is indicated by "?" at A, which occurs during initial synchronization and when received signal is lost for an extended period; unlock condition is indicated by other than " " at Q example: "216:15:36:43 " D T Q Heath GC-1000 Most Accurate Clock (WWV/H) "hh:mm:ss.f dd/mm/yy" C T A D poll: none; offsets: T = 0, D = 15, A = 9, Q = none hh:mm:ss = hours, minutes, seconds f = deciseconds ("?" when out of spec) dd/mm = day, month yy = year (from DIPswitches) note: 0?:??:??.? is displayed before synch is first established and hh:mm:ss.? once synch is established and then lost again for about a day example: "15:36:43.6 04/08/91" T A D PST/Traconex 1020 Time Source (WWV/H) (firmware revision V4.01) "ahh:mm:ss.fffs" "yy/dd/mm/ddd" "frdzycchhSSFTttttuuxx" T C D A Q poll: "QTQDQM"; offsets: T = 1, D = 24, Q = 41, A = 37 a = AM/PM indicator (" " for 24-hour mode) hh:mm:ss.fff = hours, minutes, seconds, milliseconds s = daylight-saving indicator (" " for 24-hour mode) yy = year (from DIPswitches) dd/mm/ddd = day of month, month, day of year f = frequency enable (O = all frequencies enabled) r = baud rate (3 = 1200, 6 = 9600) d = features indicator (@ = month/day display enabled) z = time zone (0 = UTC) y = year (5 = 91) cc = WWV propagation delay (52 = 22 ms) hh = WWVH propagation delay (81 = 33 ms) SS = status (80 or 82 = operating correctly) F = current receive frequency (4 = 15 MHz) T = transmitter (C = WWV, H = WWVH) tttt = time since last update (0000 = minutes) uu = flush character (03 = ^c) xx = 94 (unknown) (firmware revision X4.01.999 only) note: alarm condition is indicated by other than "8" at A, which occurs during initial synchronization and when received signal is lost for an extended periodunlock condition is indicated by other than "0000" in the tttt subfield at Q example: " 15:36:43.640 91/08/04/216 O3@055281824C00000394" ======================================================================== Timecode Receivers Following is a list of radio timecode receivers currently on the market. All of these radios provide a timecode output that can be connected to a serial port, which is used to send poll messages and receive responses. Those for which NTP support is available are identified in the list below. All radios provide a 1-pulse-per-second (PPS) output that can be connected to a serial port using a level-converter/pulse-generator described elsewhere. Many radios are available with an IRIG-B Time Code option, which is supported by the NTP Version 3 distribution xntp3. This requires a Sun workstation with audio codec. Unless indicated otherwise, the accuracy of the serial timecode is in the range of a millisecond or two relative to UTC when corrected for the receiver internal delay and signal propagation delay from the transmitter to the receiver. In general, the accuracy of the PPS and IRIG signals is much better than the timecode as indicated below. Prices are taken from the manufacturer's current literature. Model 2201A GPS Receiver Mainframe with Output Interface Option and RS232 I/O Interface Option (incl. antenna) ($12,240) Austron, Inc. P.O. Box 14766 Austin, TX 78761 (512) 251-2313 This is a UHF receiver and decoder for satellites of the Global Positioning System. It provides complete decoding of the navigation message, including the year and leap-second warning as broadcast. The accuracy of the timecode is one millisecond or better. The accuracy of the PPS and optional IRIG signals is 200 ns without the LORAN assist and 100 ns with the assist. This receiver provides the year and leap-second warnings (using special commands), as well as copious housekeeping data. The antena may be mounted up to several hundred feet from the receiver. Note: There are serious deficiencies in the design of early production models (without the -A suffix) which preclude reliable computer control of this radio. This receiver is supported in the NTP Version 3 Unix implementation xntp3. The driver also includes support for the optional LORAN Assist Option, Input Buffer, Output Buffer and IRIG Options. Model bc700LAN GPS Time Server - replaced with TYMESERVE 2000 LAN Time Server (see below) Model TYMESERVE 2000 LAN Time Server (incl. antenna) ($8000) Bancomm Division of Datum, Inc. 6541 Via del Oro San Jose, CA 95119 (408) 578-4161 FAX (408) 578-4165 This is an integrated NTP time server and reference timing source for use on an Ethernet. It can be configured to operate with a GPS receiver, ACTS telephone or external IRIG source. It produces IRIG, PPS and selectable standard frequency outputs. The GPS receiver operates with satellites of the Global Positioning System and provides a timing accuracy of one millisecond at the Ethernet connection. This receiver provides the year via NTP but no leap- second warning. The antenna may be mounted up to 1000 feet from the receiver. Model ? MSF Synchronized Clock (price unknown) European Electric Systems, Ltd. Woodham Mortimer Place, Rectory Lane Woodham Mortimer, Maldon, Essex. CM9 6SW, United Kingdom +44 24541 5785, (FAX) +44 24541 5785 This is a LF receiver for the MSF (Rugby, UK) station. It is reported they manufacture a US version for the WWVB station. No further information is available. This receiver is not supported in the NTP Version 3 Unix implementation xntp3. * Model GCW-1001 Most Accurate Clock II ($350) Heath Company Benton Harbor, MI 49022 (1 800) 253-0570 Note: The Heath Company is *back* in business, at least for this clock. This is an HF receiver and decoder for the WWV/WWVH stations. It provides the year (from internal DIPswitches), but no leap-second warning. This receiver is currently supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model GPStar Time and Frequency System ($3,995 incl. antenna) Odetics Precision Time Division 1515 South Manchester Avenue Anaheim, CA 92802 (714) 758-0400 FAX (714) 758-8463 This is a UHF receiver and decoder for satellites of the Global Positioning System. It provides an output at 1 pps plus adjustable time and frequency outputs. The antena may be mounted up to several hundred feet from the receiver. This receiver is not currently supported in the NTP Version 3 Unix implementation xntp3. Model NETCLOCK/2 Computer Clock (incl. 8206A antenna ($2485) Spectracom Corporation 101 Despatch Drive East Rochester, NY 14445 (716) 381-4827 This is an LF receiver and decoder for the WWVB station and replaces the Model 8170 WWVB Synchronized Clock, which sold for $2,500. A model for the MSF station is also available. The accuracy of the timecode is one millisecond or better; the accuracy of the PPS and optinal IRIG outputs is 100 microseconds or better. This radio provides both the year and leap-second warning as broadcast. Both the 8170 and NETCLOCK/2 radios are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model 1020 Integrated Time Source ($1,500) Traconex Corporation Mike Gerado (213) 724-0450 or Bob Young (714) 632-9510 1140 N. Kramer Blvd., Unit G Aneheim, CA 92806 (714) 632-9510 This is an HF receiver and decoder for the WWV/WWVH stations. Version 4.01 or later of the clock firmware is required. This radio, formerly marketed by Precision Standard Time, is now being marketed by the Traconex Corporation. It is reported their assets have been purchased by Meyers Electric. The accuracy of the timecode and PPS outputs is limited to a few milliseconds by the characteristics of HF signal propagation. This radio provides the year (from internal DIPswitches), but no leap-second warning. This receiver is supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model 8810 GPS Station Clock (under $10,000) Trak Systems Division 4726 Eisenhower Blvd. Tampa, FL 33634-6391 (813) 884-1411 ext 248 This is a UHF receiver and decoder for satellites of the Global Positioning System. It provides RS232 remote control and time output accurate to 100 ns. Further information is available from the manufacturer. This receiver is not supported in the NTP Version 3 Unix implementation xntp3. Model GPS-DC GPS Synchronized Clock MK III (incl. antenna) ($9,750) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is a UHF receiver and decoder for satellites of the Global Positioning System and replaces the original Model GPS-DC GPS Synchronized Clock, which sold for $12,500. It provides complete decoding of the navigation message, together with an accuracy of 100 ns relative to UTC(GPS) at the PPS output. This receiver provides the year as broadcast (using special commands), but no leap-second warning. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model GPS-805 GPS Synchronized Time Code Unit (incl. antenna) ($5,195) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is a UHF receiver and decoder for satellites of the Global Positioning System. It provides complete decoding of the navigation message, together with an accuracy of one microsecond relative to UTC(GPS) at the PPS output. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model GPS-TMS GPS Synchronized Timing Module (incl. antenna) ($3,495) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is a UHF receiver and decoder for satellites of the Global Positioning System. It provides complete decoding of the navigation message, together with an accuracy of two microseconds relative to UTC(GPS) at the PPS output. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model 468-DC MK III GOES Satellite Synchronized Clock ($5,850) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is a UHF receiver and decoder for the GOES satellite and replaces the original Model GPS-DC GPS Synchronized Clock, which sold for $5,800 (incl. antenna). This receiver provides neither the year nor leap-second warning. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model 60-DC WWVB Synchronized Clock (incl. antenna) ($2,865) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is an LF receiver and decoder for the WWVB station. This receiver provides neither the year nor leap-second warning. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model LF-DC MSF/DCF77 Synchronized Clock (incl. antenna) ($3,575) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is an LF receiver and decoder for the MSF station (Rugby, UK) and DCF77 station (Mainflingen, Germany). This receiver provides neither the year nor leap-second warning. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 and the Fuzzball operating system. Model OM-DC OMEGA Synchronized Clock (incl. antenna and preamp) ($5,925) TrueTime Division, Kinemetrics 3243 Santa Rosa Avenue Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 This is a VLF receiver and decoder for the OMEGA stations. This receiver provides neither the year nor leap-second warning. TrueTime decoder formats are supported in the NTP Version 3 Unix implementation xntp3 (using a special driver) and the Fuzzball operating system. 8101 Automated Computer Time Service (ACTS) Time and Frequency Division, National Bureau of Standards US Department of Commerce Gaithersburg, MD 20899 This is a package of C software on diskette for the IBM Personal Computer. It can be used to call a special NBS number using either 300-Hz or 1200-Hz modem and set the computer clock. The latest version has been adapted to run on Sun/Unix workstations. This service provides the year and leap-second warning. Meinberg DCF U/A 31 (DM1200 - appr. $750) Ing. (Grad.) Werner Meinberg D-31812 Bad Pyrmont, Germany +49 +5281 2018 FAX +49 +5281 608180 This is an LF receiver and decoder with an active antenna (suitable for outdoor use). Antenna cable length up to 50m. Outputs are PPS, 1-PPM, 77.5kHz, RS232 (1 telegram per second +- 3ms). No leap second warning. Supported by xntp3. Meinberg DCF PZF 535/TCXO / DCF PZF 535/OCXO (DM 2500-3300 - appr. 500- 2000) Ing. (Grad.) Werner Meinberg D-31812 Bad Pyrmont, Germany +49 +5281 2018 FAX +49 +5281 608180 This is an LF pseudo random phase shift receiver and decoder with an active antenna (outdoor antenna also available). Antenna cable length up to 50m. Outputs are PPS, 1-PPM, 77.5kHz, 155kHz, 310kHz, RS232 (1 telegram per second +- 53us). Normally no leap second warning. Supported by xntp3. There is a special xntp firmware release available on request. (PZFUERL). Meinberg GPS 166 (ca. DM 4000-5000 - appr. $2500-$3200) Ing. (Grad.) Werner Meinberg D-31812 Bad Pyrmont, Germany +49 +5281 2018 FAX +49 +5281 608180 This is a GPS receiver for stationary use. An active antenna for outdoor use is included. Cable length can go up to 100m. Outputs are: PPS, 1-PPM, 0-10Mhz (frequency synthesizer), 100kHz, 1MHz, 10Mhz and RS232 (1 telegram per second, no fixed timing (yet)) Inputs: 2xCapture (100ns resolution). Supported by xntp3. There is a special firmware release for xntp available (KARDE/Uni-Erlangen) All Meinberg clocks are 19" rack mounting modules. You still need a rack and a power supply (around DM300 - $200). ======================================================================== The following information is provided by Jerry Scharf on relatively inexpensive GPS receivers and modules. Model bc627AT GPS PC Board ($3695) Bancomm Division of Datum, Inc. 6541 Via del Oro San Jose, CA 95119 (408) 578-4161 FAX (408) 578-4165 Model 9390-52000 ($4000) Datum 1363 S State College Blvd Anaheim, Ca 92806 (714) 553-6333 Model GPSync Odetics Precision Time Division 1515 South Manchester Avenue Anaheim, CA 92802 (714) 758-0400 FAX (714) 758-8463 GPS Time-Machine ($2795) Spectrum Geophysical 1900 West Garvey Ave S., Ste 200 West Covina, Ca 91790 (714) 544-3000 GPS model 100 ($2495) Stellar 800 Charcot Ave, Suite 110 San Jose, CA 95131 (408) 383-1515 Model 8821 GPS Clock ($3500) Trak Systems Division 4726 Eisenhower Blvd. Tampa, FL 33634-6391 (813) 884-1411 ext 248 Model GPS-TMS ($3495) TrueTime Division, Kinemetrics 2835 Duike St. Santa Rosa, CA 95407 (707) 528-1230 FAX (707) 527-6640 GPS Brain Timing OEM board Magellan 960 Overland Ct. San Dimas, Ca 91773 (909) 394-5000 Acutime II OEM pod Trimble 645 N Mary Ave Sunnyvale CA 94086 (408) 481-8000 ======================================================================== Precision Oscillators and Timing Receivers For accuracies better than a millisecond or two, a precision oscillator and means of calibration relative to UTC are usually required. This can be accomplished with a cesium or rubidium standard, which is periodically calibrated with a portable standard or physically moved to a source of standard time, such as U.S. Naval Observatory in Washington, DC, or NIST in Boulder, CO. Between calibrations it is usually necessary to use some kind of radio or satellite service, such as LORAN-C or GPS, to monitor the oscillator and calibrate its particular inherent frequency offet. None of the devices listed produce a serial timecode which can be read by a computer, but all provide outputs that can be used with appropriate computer interfaces to fine-tune the indication from a timecode receiver. Note that, although several Fuzzball time servers continue to operate in the Internet, that operating system should be considered obsolete. The newer refinements of the NTP Version 3 daemon xntp3 include provisions to discipline the onboard frequency source to an external source of seconds pulses such as produced by most of the following devices. Model 5071A Cesium Beam Standard ($55,100 with clock and power supply) Hewlett Packard, Co. 19310 Pruneridge Avenue Cupertino, CA 95014 This is a cesium-beam primary standard oscillator/clock with long- term stability better than 7x10^-13 (about 60 ns per day). It produces various outputs which can be used to provide a precise frequency and time reference when used in conjunction with a timecode receiver. Used to stabilize frequency with the NTP local- clock algorithms, a time server will ensure accuracy to a millisecond even after all contact with a reference source has been lost well over the expected life of the beam tube, which is about ten years. Model 5065A Rubidium Frequency Standard ($49,000 with clock and power supply) Hewlett Packard, Co. 19310 Pruneridge Avenue Cupertino, CA 95014 This is a rubidium-vapor resonance cell secondary standard oscillator/clock with long-term stability better than 2x10^-12 (about 170 ns per day). It produces various outputs which can be used to provide a precise frequency and time reference when used in conjunction with a timecode receiver. Used to stabilize frequency with the NTP local-clock algorithms, a time server will ensure accuracy to a millisecond even after all contact with a reference source has been lost well over a year. Model 105B Quartz Oscillator ($9,050) Hewlett Packard, Co. 19310 Pruneridge Avenue Cupertino, CA 95014 This is an oven-stabilized quartz oscillator with stability better than 1x10^-10 (about 9 us per day). It produces various outputs which can be used to provide a precise frequency reference when used in conjunction with a timecode receiver. Used to stabilize frequency with the NTP local-clock algorithms, a time server will ensure accuracy to a millisecond even after all contact with a reference source has been lost over three months. Model OCXO-107 Oven-Compensated Quartz Oscillator ($700) ISOTEMP Research, Inc. Charlottesville, VA This is an oven-stabilized quartz oscillator with stability better than 1x10^-8 (about 0.9 ms per day). It produces a 5-MHz output which can be used to provide a precise frequency reference when used in conjunction with a timecode receiver. Used to stabilize frequency with the NTP local-clock algorithms, a time server will ensure accuracy to a millisecond even after all contact with a reference source has been lost over one day. Model 2950A Quartz Oscillator Frequency Standard ($900, $1200, $1800) Novatech Instruments, Inc. 1530 Eastlake Avenue East, Suite 303 Seattle, WA 98102 (206) 328-6902 This is an oven-stabilized quartz oscillator available in three grades: 1x10^-9, 1x10^-10 or 5x10^-11 per day (equivalent to about 90 us, 9 us or 4 us per day, respectively). It produces three outputs of 5MHz, 1MHz and 100kHz which can be used to provide a precise frequency reference when used in conjunction with a timecode receiver. Used to stabilize frequency with the NTP local- clock algorithms, a time server will ensure accuracy to a millisecond even after all contact with a reference source has been lost over 10 days, 3 months or 6 months. Model 2000 LORAN-C Timing Receiver ($20,000) Austron, Inc. P.O. Box 14766 Austin, TX 78761 (512) 251-2313 This is a LORAN-C receiver with stability and accuracy determined by the propagation characteristics of the LORAN-C signal. It produces various outputs which can be used to provide a precise frequency and time reference when used in conjunction with a timecode receiver. When used with domestic U.S. LORAN-C chains, it provides accuracies in the order of 100 ns. ======================================================================== Timecode Transmitters, Frequencies and Geographic Coordinates Call Location Frequencies Coordinates ------------------------------------------------------------------------ WWV Ft. Collins, CO 2.5/5/10/15/20 MHz 40:40:49.0N 105:02:27.0W WWVB Ft. Collins, CO 60 kHz 40:40:28.3N 105:02:39.5W WWVL Ft. Collins, CO 20 kHz (silent key) 40:40:51.3N 105:03:00.0W WWVH Kauai, HI 2.5/5/10/15 MHz 21:59:26.0N 159:46:00.0W CHU Ottawa, CA 3330/7335/14670 kHz 45:18N 75:45N DCF77 Mainflingen, DE 77.5 kHz 50:01N 9:00E MSF Rugby, UK 60 kHz 52:22N 1:11W TDF Allouis, FR 162 kHz 47:10N, 2:12E Oddball coordinates (note that one second of latitude is about 31 meters) Newark Hall 39:40:40N, 75:44:57W (survey NAD27) Evans Hall 39:40:48.425N, 75:45:02.392W, +74.09H (GPS WGS84) Christiana Commons 39:41:26N, 75:45:23W (survey NAD27) W3HCF Backroom 39:42:00N, 75:46:55W (USGS map NAD27) Marina del Rey, CA 33:58:49N, 118:26:20W Control Point NAD27 39:40:48 NAD83 39:40:48.39725 75:45:05 75:45:03.76078 Great-circle distance and bearing computation #define R 6371.2 /* radius of the Earth (km) */ #define PI 3.141592653589 /* the real thing */ #define D2R PI/180 /* degrees to radians */ #define VOFL 2.9979250e8 /* velocity of light (m/s)*/ #define hF 320 /* nominal height of F layer (km) */ #define MINBETA 5.*D2R /* min elevation angle (rad) */ double lat1; /* transmitter latitude (deg N) */ double lon1; /* transmitter longitude (deg W) */ double lat2; /* receiver latitude (deg N) */ double lon2; /* receiver longitude (deg W) */ double d; /* great-circle distance (rad) */ double theta; /* hour angle (rad) */ int hop; /* number of ray hops */ double beta; /* elevation angle (rad) */ double delay; /* path delay (ms) */ double dhop; /* hop angle/2 (rad) */ lat1 = lat1*D2Rlon1 = lon1*D2R; lat2 = lat2*D2Rlon2 = lon2*D2R; theta = lon2-lon1; if (theta >= PI) theta = theta-2*PI; if (theta <= -PI) theta = theta+2*PI; d = acos(sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(theta)); if (d < 0) d = PI+d; hop = d/(2*acos(R/(R+hF))); beta = 0; while (beta < MINBETA) { hop = hop+dhop = d/(hop*2); beta = atan((cos(dhop)-R/(R+hF))/sin(dhop)); } delay = 2*hop*sin(dhop)*(R+hF)/cos(beta)/VOFL*1e6; ======================================================================== Appendix. Time Synchronization Stations Stations Operated by U.S. Agencies See: Beehler, R.E., and M.A. Lombardi. NIST Time and Frequency Services. NIST SPecial Publication 432 (Revised 1990), U.S. Department of Commerce, June 1991, 30 pp. Available from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402. Covers Radio Stations WWV, WWVH, WWVB, GOES Satellite Time Code and Automated Computer Time Service (ACTS). Stations Outside the U.S. Editor's note: The following information is provided as an aid in developing timecode software for primary time servers using various national standards dissemination media. No claim is made on correctness other than by the authors listed. Information included in this version applies to DCF77 (Germany), MSF (United Kingdom), TDF (France) and CHU (Canada). ------------------------------------------------------------------------ Time and Standard Frequency Station DCF77 (Germany) (Original in German available from the address below. Translation errors courtesy of Peter Lamb, Swiss Fed. Inst. of Technology). Physikalisch-Technische Bundesanstalt (PTB) Braunschweig, Febuar 1984 Lab 1.21 Bundesalle 100 D-3300 Braunschweig Legal basis and responsibility for the transmissions from DCF77 The 1978 law on time standards defines legal time in Germany on the basis of Coordinated World Time (UTC) and gives the PTB responsibility for the keeping and broadcasting of legal time. As well as this, the time standards law empowers the Federal government to issue regulations for the introduction of Summer Time. Legal time in the FRG is either Middle European Time (MEZ - German abbreviation) or, in case of its introduction Middle European Summer Time (MESZ). The following relationships hold between UTC and MEZ and MESZ. MEZ(D) = UTC(PTB) + 1h MESZ(D) = UTC(PTB) + 2h Legal time is generated in the PTB Atomic Clock Building in Braunschweig and it is broadcast mainly through the LF transmitter DCF77 which the PTB rents from the German Post Office (DBP). The PTB has sole responsibility for the control of DCF77, while the DBP has responsibility for the transmitter and antennas. Queries should be directed to the above address or by telephone to 0531/592 1212 or 0531/592 1210, or by telex to 952822 ptb d. DCF77 Specifications Location: Mainflingen transmitter complex, (50:01N, 09:00E), about 25km south-east of Frankfurt a. Main. Carrier Frequency: Standard frequency 77.5kHZ, derived from the PTB atomic clocks. Relative deviation of the carrier from specifications: averaged over 1d: <1e-12 averaged over 100d: <2e-13 The carrier phase is controlled so that deviations relative to UTC(PTB) are never greater than +-0.3us. Larger phase and frequency variation observed at the receiver are due to summation of ground and space waves. Power output: Transmitter power 50kw, estimated emitted power approx. 25kW. Antenna: 150m high (backup antenna 200m high) vertical omnidirectional antenna with top capacitance. Transmission times: 24-hour continuous service. Short interruptions (of a few minutes) are possible if, because of technical problems or servicing, the service must be switched to a backup transmitter or antenna. Thunderstorms can cause longer interruptions to the service. Time signal: The carrier is amplitude-modulated with second marks. At the beginning of each second (with the exception of the 59th second of each minute), the carrier amplitude is reduced to 25% for the duration of either 0.1 or 0.2 seconds. The start of the carrier reduction marks the precise beginning of the second. The minute is marked by the absence of the previous second mark. The second marks are phase-synchronous with the carrier. There is a relatively large uncertainty possible in the time of the second mark which depends on the receiver position. The causes are the relatively low bandwidth of the antenna, space wave and other interference sources. Despite this, it is possible to achieve accuracy better than 1ms at distances of several hundred kilometers. Time code: The transmission of the numerical values for minute, hour, day, weekday, month and year are BCD-encoded through the pulse duration modulation of the second marks. A second mark with duration 0.1s encodes a binary 0 and a duration of 0.2s encodes 1. The order of encoding is shown in the following diagram [replaced by a table in this translation]. The three test bits P1, P2 and P3 extend the 3 major sections of the time code (7 bits for minutes, 6 bits for the hour and 22 bits for the date, including the week day number) to maintain an even count of 1's. The second marks No. 17 and 18 indicate the time system for the transmitted time codes. In the case of transmission of MEZ, mark 18 has a duration of 0.2s and mark 17 a duration of 0.1s. If MESZ is being transmitted, this is reversed. Furthermore, an approaching transition from MEZ to MESZ or back is announced by extending mark 16 from 0.1 to 0.2s for one hour prior to the changeover. Encoding Scheme [diagram in original] Mark number(s) Encodes (01.s=0, 0.2s=1) 0 Minute, always 0 (0.1s) 1-14 Reserved 15 0=Normal antenna, 1=backup antenna 16 1=Approaching change from MEZ to MESZ or back 17,18 Time zone 0,1=MEZ; 1,0=MESZ 19 The leap second is encoded in this bit one hour prior to occurrence. 20 Start bit for encoded time, always 1 21-27 1, 2, 4, 8, 10, 20, 40 Minutes (mark 21=1 minute) 28 P1 maintains even parity for marks 21-28 29-34 1,2,4,8,10,20 Hours (mark 29=1 hour) 35 P2 maintains even parity for marks 29-35 36-41 Day in month (1, 2, 4, 8, 10, 20) 42-44 Day in week (1,2,4) 45-49 Month number (1, 2, 4, 8, 10) 50-57 Year (1, 2, 4, 8, 10, 20, 40, 80) 58 P3 maintains even parity for marks 36-58 There is no mark transmitted for the 59th second. Literature P. Hetzel, "Die Zeitsignal- und Normalfrequenzaussendungen der PTB ueber den Sender DCF77: Stand 1982" [The PTB time signal and standard frequency transmissions from DCF77: Status 1982] in "Funkuhren" [Radio clocks], W. Hilberg, Oldenburg Publishers, Munich & Vienna 1983, pp 42- 57. G Becker & P. Hetzel, "Vortraege ueber DCF77" [Lectures: DCF77], PTB Reports, PTB-Me-23 (1979), pp 185-253. Braunschweig 1984 Additional information: DCF77 Since July 1983, the DCF77 carrier has been phase modulated in a test configuration. The phase modulation is a pseudorandom binary sequence sent twice each second. The clock frequency of the binary sequence is 645.833...Hz and the phase shift \Delta\tau about 3% of the period (\^{=} 10\deg). Equal numbers of shifts of +\Delta\tau and -\Delta\tau are always sent, so that the mean frequency remains unchanged, and the use of DCF77 as a frequency standard is unaffected. The timecode is encoded in the sequence by inverting the sequence or not. Not inverted sequence corresponds to a 0 bit. The sequence is alleged to be generated by a 9 bit shift register which is coupled back on positions 5 and 9. The polynomial might be: x^9 + x^4 + 1. Because the pseudo-random bitstring has a strictly deterministic nature, the correlation analysis at the receiver end leads to a correlation function with triangular form, and thereby to timing information. Early test results show that the time information received with the help of pseudo-random phase modulation is more resistant to interference and more accurate (standard deviation \approx 10\mu s during the day and \approx 25\mu s at night) than the conventional method using amplitude modulated second marks. Since this new modulation method is compatible with previous usage of DCF77, and that the users have made no difficulties known to us, the tests have been extended. The transmission of the pseudo-random phase distortion still has experimental status, and should not be seen as a permanent commitment. Further information will be made available in the future. Announcement bit for a leap second The DCF77 control unit is currently being modified so that in future an announcement bit for a leap second can be sent. It is expected that for the first time on 1st July 1985 the second mark Nr. 19 will be extended to a length of 0.2s for one hour prior to the introduction of a leap second. Intelligent receivers will then be able to recognise the discontinuity and maintain correct indicated time in spite of a 61s minute. Availability The clock was made by a local radio amateur. Empfangsanlage DCF77 (SFr 690. complete, also available in kit form) Walter Schmidt Eichwisrain 14 8634 Hombrechtikon Switzerland LF reciever and decoder for the German time standard DCF77. As yet untested. Has a 1s impulse output driven direct from the reciever, which could be used in a similar manner to the pulse output on the Spectracom. Internal crystal-controlled clock reset each minute by the DCF77 minute mark. Indication available to program of whether currently synchronised, and a count of how long since the last synchronisation is available if running unsynchronised. Returns time with resolution 0.1s, but probably synchronised to the time of command reception, and not to the 0.1s counter. I will try to get the firmware changed if this is the case. Other sources Die folgende Liste ist einer Information der PTB entnommen. Fuer evtl. Tippfehler wird nicht gehaftet (;-) (Umlaute sind in ASCII Umschrift (ae,oe,ue,ss) dargestellt.) Am 1 Juli 1993 wurde diese Liste auf die neuen Postleitzahlen umgestellt. Die alten Postleitzahlen stehen in runden Klammern - einige konnten nicht korrigiert werden (Korrekturen werden gerne angenommen). Bei Erweiterungen/Aenderungen bitte email an time@informatik.uni- erlangen.de Note: This document was corrected for the new zip codes on July 1st 1993. The old zip codes are in parenthesis. Some zip codes could not be converted. Last update: 91/06/05 - 13:34:36 Januar 1989 (PTB Original) Hersteller/Vetriebsfirmen von DCF77-Empfangsgeraeten ---------------------------------------------------- 1. Funkuhren fuer Zeitdienst-Systeme (z. B. Funkuhren fuer Uhren- anlagen und Turmuhr-Zentralen; modulare Funkuhren mit RS 232- Schnittstelle fuer Rechner; funkgesteuerte Schaltuhren, Zeit- kodegeneratoren und Aussenuhren) kodegeneratoren und Aussenuhren) Auerswald GmbH & Co. KG Vor den Grashoefen 1 Tel.: 05306/92000 38162 (3302) Cremlingen, OT Schandelah Electronic Design Buero Zeilstrasse 56 Herwig Braun GmbH 72793 (7417) Pfullingen Tel.: 07121/71560 Ferrari electronic GmbH Beusselstrasse 27 Tel.: 030/3965021 10553 (1000) Berlin (21) Gesellschaft fuer Datensysteme (GDS) Hindenburgstrasse 13 Tel.: 05306/7010 38162 (3302) Cremlingen OT Schandelah Heliowatt Werke Wilmersdorfer Str. 39 Elektrizitaets-Gesellschaft mbH 10627 (1000) Berlin (12) Tel.: 030/31908-01 Hopf Elektronik Postfach 18 47 Tel.: 02351/45038 58468 (5880) Luedenscheid Philip Hoerz Moltkestrasse 6 Turmuhren 89077 (7900) Ulm Tel.: 0731/37168 Marcel Kreutler Postfach 37 44 Zeit- und Informationstechnik 67050 (7500) Karlsruhe (1) Tel.: 0721/85281 Landis & Gyr GmbH Friesstrasse 20 - 24 Tel.: 069/40020 60388 (6000) Frankfurt (60) Lennartz Elektronic GmbH Bismarkstrasse 136 - not translated Tel.: 07071/3088 (7400) Tuebingen Werner Meinberg Elektronik Auf der Landwehr 22 Tel.: 05281/2018 31812 (3280) Bad Pyrmont Aus dem Moore Postfach 21 41 Turmuhr-Elektronik 32361 (4994) Preussisch Tel.: 05742/5225 Oldendorf 2 Moser-Baer AG CH-3454 Sumiswald Tel.: 0041/34/721144 Schweiz Noelpp-Informationssysteme GmbH Friedensstrasse 41 Tel.: 06101/87592 61118 (6368) Bad Vilbel (2) Heinrich Perrot Postfach 13 51 Turmuhrenfabrik 75353 (7260) Calw-Heumaden Tel.: 07051/12055 Precitel SA Avenue du Mail 59 Tel.: 0041/38/247555 CH-2000 Neuchatel Schweiz Georg Rauscher Wuerzburgerstrasse 4 Turmuhrenfabrik 93059 (8400) Regensburg Schwille-Elektronik Benzstrasse 1 Tel.: 089/9031041 85551 (8011) Kirchheim Siemens AG Postfach 53 29 Tel.: 0511/1290 30053 (3000) Hannover (1) Telefunken electronic Ringlerstrasse 17 Tel.: 0841/8811 85057 (8070) Ingolstadt Telenorma Uhren GmbH Postfach 44 32 - not translated Tel.: 069/266-1 (6000) Frankfurt (1) ZERA Elektronische Pruefgraete Postfach 11 60 Cremer & Co. 53621 (5330) Koenigswinter Tel.: 02223/22075 2. Funkuhren fuer den haeuslichen Gebrauch (z. B. Tisch- und Wand- uhren der Firmen Dugena, Hermle, Junghans, Kundo,...) Vertrieb durch den Uhrenfachhandel und die Fachabteilungen von Kauf- und Versandhaeusern 3. Funkuhr-Bausaetze und -Fertiggeraete Vertrieb durch den Elektronik-Fach- und Versandhandel 4. DCF77-Normalfrequenzempfaenger und Frequenzregler fuer Normal- frequenzoszillatoren Goerl HF-Messtechnik Buchenstrasse 2 Tel.: 0821/482613 86356 (8902) Neusaess 4 Rohde & Schwarz Muehldorfstrasse 15 Tel.: 089/4129-0 81671 (8000) Muenchen (80) 0911/86747 (Nuernberg) Unverdross Technik Tutzinger Hof Platz 6 Tel.: 08151/21198 82319 (8130) Starnberg Die mit `*' gekennzeichneten Firmen unter 1. haben neben Funkuhren auch DCF77-Normalfrequenzempfaenger in ihrem Vertriebsprogramm. Diese Liste wurde erstellt aufgrund von Informationsmaterial, das der PTB ueber DCF77-Empfangsgeraete vorliegt. Falls neue Produkte auf den Markt kommen, eine Firma uebersehen wurde oder eine hier aufgefuehrte Firma die Produktion von DCF77-Empfangsgeraeten einge-stellt hat, bittet die PTB um Zusendung von entsprechenden Infor-mationen, damit diese Zusammenstellung aktualisiert werden kann. ------------------------------------------------------------------------ Time and Frequency Station MSF (United Kingdom) Information entered by Philip Gladstone, extracted from a document issued by Rugby (VLF) Radio Station. Technical Details Service MSF 60 KHz Radiated Power 16 KW Schedule 24 hour (off for maintenance 1000-1400 GMT on the first Tuesday of the month) Duration of time signal emission Continuous Time signal modulation A1 Negative 100mS at the second, 500mS at the minute Epoch at Carrier Fall Carrier Frequency Stability +/- 3 in 10^12 Time Signal Accuracy 0.1mS relative UTC The Rubgy Frequency Standards Three Hewlett Packard sources are used -- one type 5061A Caesium Beam,and two type 5065A rubidium vapour -- and are installed in acontrolled-environment cubicle together with an AUSTRON type 2055 microstepper. This last is a precision rate adjuster which is used to vary the frequency of the Caesium standard to cater for the minute differences (of order parts in 10^12) which exist between all Caesium standards. This results in a 5MHz output from a crystal oscillator which is part of the feedback system. The 60KHz carrier is derived from this 5MHz by a digital tripler consisting of three positive edge detectors on a delay line using the propagation delay in integrated circuit inverters to produce three pulses seperated by 66.6 nanoseconds in each 200nS cycle of 5MHz. The resulting 15 MHz is then divided by 250 to obtain a square wave at 60 KHz. 100 KHz outputs are used to drive the digital clocks -- three Venner TSA 5586 clocks which give parallel BCD time output. These clocks are set an arbitrary 100 microseconds ahead of UTC (Rugby) to cater for the unavoidable delays in drive generators and transmitters. Time Stability 1. UTC (Rugby) is compared with UTC (NPL) by measurements at both sites relative to a readily identifiable edge in the field sync pulse train of the BBC TV transmission from Sandy Heath 2. UTC (NPL) is compared with UTC (BIH) by similar observations of a specified feature in the transmission from Sylt (7970-W) in the LORAN 'C' Norwegian Sea chain. 3. Rugby then use results supplied by BIH and NPL to calculate a direct comparison between UTC at Rugby and BIH. It should be noted that UTC (BIH) is a calculated 'paper' clock with no physical existence of its own and actually derived from the average of 30 or so standard clocks throughout the world. UTC (Rugby) is currently maintained within 4 parts in 10^13 of agreement with UTC (BIH), a comfortable margin over the claimed stability of 3 in 10^12. Why called MSF? It is a callsign like 2LO and GBR and while SF was the obvious acronym for Standard Frequency a three letter callsign could only begin with 2, G or M, the prefixes allocated to the UK by international agreement for station identification. M was available for use with the letters SF, G was not, so there was really very little choice in the matter. Pulse Train The Minute epoch is marked by a 500 mS break in the carrier. Actually, there is data transmitted in this gap, but very few people use it. There are four other types of signal that can be sent on the second. ______ _______________ | | | | Zero (normal marker) |_____| ______ _______________ | | | | One (Time, date, identifier) |__________| ______ _______________ | | | | Identifier one plus Parity or |_______________| BST one ______ ____ _______________ | | | | | | | | DUT1 one |_____| |____| ^ ^ ^ ^ | | | 300 ms | | 200 ms | 100 ms 0 (Second Epoch) Second 0 500ms break (100 Hz code) 1-8 Positive DUT1 (use either Zero or DUT1) 9-16 Negative DUT1 (use either Zero or DUT1) 17-24 Year (80,40,20,10,8,4,2,1) (Use Zero or One) 25-29 Month (10,8,4,2,1) (Use Zero or One) 30-35 Day (20,10,8,4,2,1) (Use Zero or One) 36-38 Day of Week (4,2,1) (Use Zero or One) 39-44 Hour (20,10,8,4,2,1) (Use Zero or One) (Localtime) 45-51 Minute (40,20,10,8,4,2,1) (Use Zero or One) 52 Zero 53 BST/UTC Change next hour (Use One or Ident) 54 Parity (over 17-24) (Use One or Ident) 55 Parity (over 25-35) (Use One or Ident) 56 Parity (over 36-38) (Use One or Ident) 57 Parity (over 39-51) (Use One or Ident) 58 BST (Use One or Ident) 59 Zero Notes 1. The 1Hz data applies to the following minute 2. When BST is in force, bit 58 is 300 mS and Data is 61 minutes fast of UTC. Bit 53 is 300 mS for the hour preceeding (0100 UTC) changes to and from BST. 3. Day 0 is Sunday 4. Parity sense is Odd. 5. The first 'n' bits in the DUT1 code being DUT1 (rather than Zero) indicates 0.'n' positive or negative DUT1. DUT1 is set up on switches to instructions via the Royal Greenwich Observatory, changes occurring approximately every five weeks. GMT is Greenwich Mean Time -- this is really UTC BST is British Summer Timer which is one hour ahead of GMT. Details of this can be obtained from Division of Electrical Science National Physical Laboratory Queens Road Teddington Middlesex TW11 0LW United Kingdom Decoding Clocks A number of clocks are available in the UK, ranging from wall clocks at around 100 UKP to digital computer clocks at 1000-2000 UKP. Hobbyist kits are also available at around 20 UKP that provide the raw 1 Hz data. ------------------------------------------------------------------------ Time and Standard Frequency Station TDF (France) Provided courtesy of Richard B. Langley, University of New Brunswick Station: TDF, Allouis, France Address: Centre National d'Etudes des Telecommunications PAB - STC - Etalons de frequence et de temps 196 avenue Henri Ravera F - 92220 Bagneux France Coordinates: 47d 10' N, 2d 12' E Frequency: 162 kHz Power: 2,000 kW Schedule: continuous except every Tuesday from 01:00 to 05:00 UTC Form of Time Signals: TDF is an amplitude modulated longwave broadcasting station, transmitting the programs of the France-Inter Network of Telediffusion de France (TDF). Time signals are transmitted by phase modulation of the carrier by + and -1 radian in 0.1 s every second except the 59th second of each minute. This modulation is doubled to indicate binary 1. The numbers of the minute, hour, day of the month, day of the week, month and year are transmitted each minute from the 21st to the 58th second, in accordance with the French legal time scale. In addition, a binary 1 at the 17th second indicates that the local time is 2 hours ahead of UTC (i.e., summer time), a binary 1 at the 18th second indicates when the local time is 1 hour ahead of UTC (i.e., winter time). A binary 1 at the 14th second indicates that the current day is a public holiday (14 July, Christmas, etc.) and a binary 1 at the 13th second indicates that the current day is the day before a public holiday. Relative Uncertainty of the Carrier Frequency: 2 parts in 10^12. Radio Clocks Available: Horloge 59 HF BHL Electronique Zone Industrielle B.P. 8 F - 14540 Bourguebus France Recepteur horaire sur France-Inter G-O Dyna Electronique 36 avenue Gambetta F - 75980 Paris Cedex 20 France RTD 101 telematique SA Zirst-chemin des pres F - 38240 Meylan France Information Sources: Annual Report of the BIPM Time Section for 1989, Bureau International des Poids et Mesures, Pavillon de Breteuil, F - 92312 Sevres Cedex, France. Zeitzeichensender / Time Signal Stations (bilingual: German and English) by Gerd Klawitter, Siebel Verlag, Bonhoeffer Weg 16, D-5309 Meckenheim, Germany. The phase modulation pattern. ----------------------------- One signal element consists of the following : the phase of the carrier is advanced linearly up to +1 radian in 0.025 second, then retarded linearly up to -1 rad in 0.050 second, then advanced again to reach zero after another 0.025 second. One signal element is always sent at each second between 0 and 58. The epoch is when the down ramp crosses zero. If a '1' bit is to be stransmitted, two signal elements are sent in sequence. Since the phase is the integral of the frequency, to this triangular phase modulation corresponds a square frequency modulation with an amplitude of about + and - 6Hz. binary '0' binary '1' / \ / \ / \ phase ___ / \ ___ ___ / \ / \ ___ \ / \ / \ / \ / \ / \ / (0.025 s | | | | | | | | | | | | | | ticks) | | epoch epoch __ __ __ _____ __ | | | | | | | | | | frequency ___| | | |___ ___| | | | | |___ | | | | | | |_____| |_____| |_____| Both the average phase and the average frequency deviation are thus zero. More data is sent by phase modulation during the rest of each second. But the second marker (and data bit) is always preceded by 0.1 second without modulation. There is no marker at the beginning of the 59th second, nor any data sent during the entire duration of that second. The binary encoding of date and time data. ------------------------------------------ Seconds 20 to 58 carry exactly the same information as the signal of the German transmitter DCF77. ------------------------------------------------------------------------ Time and Frequency Station CHU (Canada) Information provided by Nick Sayer (mrapple@quack.sac.ca.us) CHU is a radio station in Canada that broadcasts time of day information sort of like WWV. CHU transmits on 3330 kHz, 7335 kHz, and 14670 kHz using AM compatable single-sideband full carrier modulation. Between 31 and 39 seconds (inclusive) past the minute, CHU transmits a computer readable timecode. This timecode includes time of day UTC, day of year (1-366), Gregorian year, leap second warning, DUT (the difference between UTC and UT1, which is an astronomical timescale. The difference is an integral number of tenths of a second between -.9 and +.9. If the difference exceeds .7, they schedule a leap second), and a Canadian daylight time indicator. The datastream is in the form of an AFSK datastream. The frequencies are compatable with the Bell 103 standard: 2225 Hz mark and 2025 Hz space. The carrier is active between 10 and 510 msec past the second. Each byte of data is encoded as one start bit, 8 data bits and two stop bits. There are ten bytes in each packet, and the last stop bit ends at precisely 500 msec past the second. ( 1 start bit + 8 data bits + 2 stop bits ) 10 characters = 110 bits. Each bit takes 1/300 of a second (300 baud). So the whole code takes 366.66.. msec. 500-366.66... = 133.33... msec. So graphically, each second looks like this: 000 050 100 150 200 250 300 350 400 450 500 550 | | | | | ^ ^ ^ ^ ^ 1 2 3 4 5 1 - Ticking noise. 2 - 2225 Hz mark tone for 123.333 msec to allow modems to set up 3 - Data stream 4 - 2225 Hz mark tone for 10 msec to avoid false overrun of the stop bits 5 - silence until the end of the second. The datastream itself consists of ten bytes. There are two possible formats at the moment: One for second 31 and the other for seconds 32 through 39. Each format has 5 bytes of data, then 5 bytes of redundancy. The "A" format redundancy bytes are exactly the same as the data bytes. The "B" format redundancy bytes are exactly inverted (one's complement, NOT, XOR 0xff, etc) from the data bytes. This is how one can tell what sort of frame was received. Once the data is received and the redundancy bytes are checked, the next thing to do is to swap the least and most significant nibbles in each byte. After doing all of this, the frames look like this: A frame: 6d dd hh mm ss ddd is the day of the year. hh:mm:ss is the time UTC. 6 is a constant. Each nibble is a BCD digit. B frame: xd yy yy tt ab d is the absolute value of DUT in tenths of a second. yyyy is the gregorian year, tt is the difference between TAI and UTC, a is a flag indicating canadian daylight time (contents of this nibble are undocumented at the moment), b is a serial number (this nibble increments whenever the B frame is changed), and x is a bitwise field: 8 4 2 1 | | | | | | | +--- The sign of DUT (0=+). | | +------ Leap second warning. One second will be added. | +--------- Leap second warning. One second will be subtracted. +------------ Even parity bit for this nibble. A sample A frame as received from the modem might look like this: 36 56 21 51 53 36 56 21 51 53 Note that these numbers are in hex. This translates to the 365th day of the year (Dec 31, or Dec 30 in a leap year), 12:15:35 UTC. A sample B frame as received from the modem might look like this: 19 91 39 72 00 e6 6e c6 8d ff This translates to a DUT of -.1, year 1993, TAI-UTC=27, serial number 0 and no canadian daylight time.