time sources : Java Glossary


time sources
In our technological world there are many ways you can get the current time and date. Here is an eclectic list of time sources:
  1. From GPS satellites. GPS (Global Positioning System) provides a most excellent time source since it naturally compensates for propagation delay and is immune to network congestion and weather.
  2. setclock icon  SetClock is a Java Applet you can run on your PC (Personal Computer). It will get the accurate time from an atomic clock on the web provided by pool.ntp.org.
  3. From an atomic clock timeserver on the web using NTP NTP (Network Time Protocol). Timeservers come is various grades of accuracy. You are not supposed to pester the very accurate ones. They are for the secondary servers.
    NTP Time Servers
    Where Server IP (Internet Protocol) Can Use
    AM ntp.adc.am
    AO ao.pool.ntp.org
    AR ar.pool.ntp.org
    AR tick.nap.com.ar
    AR tock.nap.com.ar
    AT at.pool.ntp.org
    AU au.pool.ntp.org
    AU ntp.sjkwi.com.au
    AU ntp.tourism.wa.gov.au
    AU ntp1.tpg.com.au
    AU ntp2.tpg.com.au
    Africa africa.pool.ntp.org
    Asia asia.pool.ntp.org
    BA ba.pool.ntp.org
    BD bd.pool.ntp.org
    BE be.pool.ntp.org
    BE ntp1.belbone.be
    BE ntp2.belbone.be
    BG bg.pool.ntp.org
    BR a.ntp.br
    BR b.ntp.br
    BR br.pool.ntp.org
    BR c.ntp.br
    BR ntp.pads.ufrj.br
    BR ntp.pop-pr.rnp.br
    BR ntp1.pucpr.br
    BS bs.pool.ntp.org
    BY by.pool.ntp.org
    CA ca.pool.ntp.org
    CA ntp1.cmc.ec.gc.ca
    CA ntp1.linuxhosted.ca
    CA ntp2.cmc.ec.gc.ca
    CA ntp2.linuxhosted.ca
    CA ntp3.linuxhosted.ca
    CA time.chu.nrc.ca
    CA time.nrc.ca
    CA SK Regina timelord.uregina.ca
    CH b.ntp.madduck.net
    CH c.ntp.madduck.net
    CH ch.pool.ntp.org
    CH clock.tix.ch
    CH ntp.favey.ch
    CH ntp.metas.ch
    CH ntp11.metas.ch
    CH ntp12.metas.ch
    CH tack.meteonews.ch
    CH tick.meteonews.ch
    CL cl.pool.ntp.org
    CN cn.pool.ntp.org
    CN hshh.org
    CN t1.hshh.org
    CN t2.hshh.org
    CN t3.hshh.org
    CR cr.pool.ntp.org
    CZ cz.pool.ntp.org
    CZ ntp.cgi.cz
    CZ ntp.globe.cz
    CZ ntp.ujf.cas.cz
    DE a.ntp.madduck.net
    DE de.pool.ntp.org
    DE gwyn.kn-bremen.de
    DE hera.limescope.net
    DE localh0rst.de
    DE ntp.dianacht.de
    DE ntp.rueckgr.at
    DE ntp1.madavi.de
    DE ntp1.theremailer.net
    DE ntp2.hauke-lampe.de
    DE ntp2.madavi.de
    DE stratum2-3.NTP.TechFak.Uni-Bielefeld.de
    DE stratum2-3.NTP.TechFak.Uni-Bielefeld.de
    DE stratum2-4.NTP.TechFak.Uni-Bielefeld.de
    DE time.edv-froehlich.de
    DE time2.one4vision.de
    DE zeus.limescope.net
    DK dk.pool.ntp.org
    DK ntp.dvconsulting.dk
    DK ntp.gal.dk
    DK ntp2.vlh.dk
    EE ee.pool.ntp.org
    ES es.pool.ntp.org
    ES hora.oxixares.com
    Europe europe.pool.ntp.org
    FI fi.pool.ntp.org
    FI ntp.lekksi.com
    FI tick.keso.fi
    FI tock.keso.fi
    FR fr.pool.ntp.org
    FR ntp.crifo.org
    FR ntp.demongeot.biz
    FR ntp.home-dn.net
    FR ntp.obspm.fr
    FR ntp.via.ecp.fr
    FR Lyon ntp.univ-lyon1.fr
    GR gr.pool.ntp.org
    GR ntp.mfa.gr
    HK hk.pool.ntp.org
    HR hr.pool.ntp.org
    HR os.ntp.carnet.hr
    HR ri.ntp.carnet.hr
    HR st.ntp.carnet.hr
    HR zg1.ntp.carnet.hr
    HR zg2.ntp.carnet.hr
    HU hu.pool.ntp.org
    HU ntp.mandrivalinux.hu
    HU time.kfki.hu
    ID id.pool.ntp.org
    IE ie.pool.ntp.org
    IE ntp.maths.tcd.ie
    IE Dublin salmon.maths.tcd.ie
    IL il.pool.ntp.org
    IN in.pool.ntp.org
    IR ir.pool.ntp.org
    IT ntp.prato.linux.it
    JP jp.pool.ntp.org
    KR cse.inha.ac.kr
    KR kr.pool.ntp.org
    LK lk.pool.ntp.org
    LT lt.pool.ntp.org
    LU lu.pool.ntp.org
    LV lv.pool.ntp.org
    MD md.pool.ntp.org
    MD ntp.fedoramd.org
    MD ntp2.idsi.md
    MG mg.pool.ntp.org
    MK mk.pool.ntp.org
    MX mx.pool.ntp.org
    MY my.pool.ntp.org
    NC nc.pool.ntp.org
    NL nl.pool.ntp.org
    NL ntp.edge.tillo.ch
    NL ntp.minian.org
    NL ntp.wsrs.net
    NO fartein.ifi.uio.no
    NO no.pool.ntp.org
    NO ntp-public.uit.no
    NZ ntp.iprolink.co.nz
    NZ ntp.massey.ac.nz
    NZ ntp.public.otago.ac.nz
    NZ nz.pool.ntp.org
    NZ tk1.ihug.co.nz
    NZ tk2.ihug.co.nz
    NZ tk3.ihug.co.nz
    North America 0.north-america.pool.ntp.org
    North America 1.north-america.pool.ntp.org
    North America 2.north-america.pool.ntp.org
    North America 3.north-america.pool.ntp.org
    OM om.pool.ntp.org
    Oceania oceania.pool.ntp.org
    PA ntp1.linocomm.net
    PA pa.pool.ntp.org
    PK pk.pool.ntp.org
    PL ntp2.net.icm.edu.pl
    PL ntp2.radioalfa.pl
    PL pl.pool.ntp.org
    PT ntp04.oal.ul.pt
    PT pt.pool.ntp.org
    RO ntp1.dooh.ro
    RO ro.pool.ntp.org
    RS rs.pool.ntp.org
    RU ntp.letinet.ru
    RU ntp.psn.ru
    RU ntp1.kangran.su
    RU ntp2.kangran.su
    RU ru.pool.ntp.org
    RU ticktock.net.ru
    SE ntp.systemtid.se
    SE se.pool.ntp.org
    SE time.flygplats.net
    SG sg.pool.ntp.org
    SI ntp1.arnes.si
    SI ntp2.arnes.si
    SI si.pool.ntp.org
    SK sk.pool.ntp.org
    SV sv.pool.ntp.org
    South America south-america.pool.ntp.org
    South Australia ntp.adelaide.edu.au
    TH th.pool.ntp.org
    TR ntp1.sibernet.com.tr
    TR ntp1.sibernet.com.tr
    TR tr.pool.ntp.org
    TW tw.pool.ntp.org
    TZ tz.pool.ntp.org
    UA ntp.vc.ukrtel.net
    UA ua.pool.ntp.org
    UK extntp0.inf.ed.ac.uk
    UK extntp1.inf.ed.ac.uk
    UK ntp.cis.strath.ac.uk
    UK ntp.exnet.com
    UK ntp.markyate.net
    UK ntp.pinklemon.net
    UK ntp1.uk.uu.net
    UK tick.myodn.ch
    UK uk.pool.ntp.org
    UK Manchester ntp2a.mcc.ac.uk
    UK Manchester ntp2b.mcc.ac.uk
    UK Manchester ntp2c.mcc.ac.uk
    UK Manchester ntp2d.mcc.ac.uk
    UK Scotland Glasgow ntp.cs.strath.ac.uk
    US ac-ntp0.net.cmu.edu
    US ac-ntp1.net.cmu.edu
    US ac-ntp2.net.cmu.edu
    US morose.quex.org
    US ntp.myfloridacity.us
    US ntp.rfnj.org
    US ntp1.chrisjohnston.org
    US ntp1.sjbcom.com
    US ntp1.stsn.net
    US ntp2.chrisjohnston.org
    US ntp3.stsn.net
    US ntp5.tamu.edu
    US ntppub.tamu.edu
    US saman-gh.co.uk
    US thecraag.com
    US us.pool.ntp.org
    US AZ decimal.lib.ci.phoenix.az.us
    US AZ dewey.lib.ci.phoenix.az.us
    US AZ ntp3.linocomm.net
    US CA clock.develooper.com
    US CA ntp.drydog.com
    US CA ntp.nblug.org
    US CA ntp.ucsd.edu
    US CA ntp1.sf-bay.org
    US CA reva.ziaspace.com
    US CO ntp1.linuxmedialabs.com
    US DE Newark louie.udel.edu
    US GA rolex.usg.edu
    US IL ntp.mya.org
    US IL stratum2.ord2.publicntp.net
    US IL Urbana-Champaign ntp-0.cso.uiuc.edu
    US IL Urbana-Champaign ntp-1.cso.uiuc.edu
    US IL Urbana-Champaign ntp-2.cso.uiuc.edu
    US KS ntp1.kansas.net
    US KS ntp2.kansas.net
    US MA timelord.w1nr.net
    US MN ns.nts.umn.edu
    US MN nss.nts.umn.edu
    US MN ntp.skoglundtech.com
    US MN ntp157.sntp.us
    US MO time-ext.missouri.edu
    US MT chronos1.umt.edu
    US MT chronos2.umt.edu
    US MT chronos3.umt.edu
    US NC clock1.unc.edu
    US NJ tick.jrc.us
    US NJ tock.jrc.us
    US NV cuckoo.nevada.edu
    US NV tick.cs.unlv.edu
    US NV Las Vegas tock.cs.unlv.edu
    US NY alice.ziaspace.com
    US NY andromeda.ziaspace.com
    US NY ntp.pbx.org
    US NY ntp0.cornell.edu
    US NY sundial.columbia.edu
    US NY New York ntp.ctr.columbia.edu
    US NY New York timex.cs.columbia.edu
    US PA fuzz.psc.edu
    US PA University Park clock.psu.edu
    US TX chrono.cis.sac.accd.edu
    US TX ntp.bytestacker.com
    US TX ntp.fwwds.com
    US TX ntp.jentfoo.com
    US TX ntp.tmc.edu
    US TX ntp1.jtsage.com
    US TX sundial.cis.sac.accd.edu
    US TX tick.jpunix.net
    US TX tick.mattnordhoff.com
    US TX ticker.cis.sac.accd.edu
    US TX time.xenscale.com
    US VA ntp-1.vt.edu
    US VA ntp-2.vt.edu
    US VA ntp-3.vt.edu
    US VA ntp-4.vt.edu
    US VA Blacksburg vtserf.cc.vt.edu
    US WA tick.mtnlion.com
    US WI ntp1.netwrx1.com
    US WI ntp3.netwrx1.com
    US WI ntp3.sf-bay.org
    US WI Madison ntp1.cs.wisc.edu
    US WI Madison ntp2.cs.wisc.edu
    US WI Madison ntp3.cs.wisc.edu
    VE ve.pool.ntp.org
    VN vn.pool.ntp.org
    YU yu.pool.ntp.org
    ZA za.pool.ntp.org
    worldwide pool.ntp.org
    Last revised/verified: 2010-03-15
  4. java.lang.System.currentTimeMillis () will give you the time in milliseconds since 1970 Jan 1 0:00 GMT (Greenwich Mean Time). This is your best bet for computing elapsed times. Freshly minted  java.util.Dateutil.Date objects contain the current GMT date/time stamp as do freshly minted java.util. GregorianCalendar objects.
  5. Time.gov is a government website that will give you local time.
  6. XP, W2003, Vista, W2008, W7-32, W7-64, W8-32 and W8-64 will consult a Microsoft web clock if you issue the command w32tm.exe /resync or right click the time display in the bottom right and select adjust date and time ⇒ Internet time. If time.windows.com time source is not reliable, (the usual case) you can configure the timeserver to a different one, perhaps from pool.ntp.org, e.g. us.pool.ntp.org, 0.ca.pool.ntp.orgw32tm.exe will only work after the W32Time service is started in the Windows task manager.
  7. pool.ntp.org maintains a set of servers all over the world. You can find one just by prefixing your 2-letter country code e.g ch.pool.ntp.org for Switzerland or 0.ca.pool.ntp.org for Canada or us.pool.ntp.org for the USA. The W32Time service must be running for W32tm.exe to work. You can start it from the command line with sc.exe start W32Time.
  8. atomic wall clock From the NIST (National Institute of Standards and Technology) WWVB radio signal broadcast from Fort Collins, Colorado. This is how high tech wall clocks and wrist watches maintain perfect time and know when to flip back and forth to daylight savings. They are called analog atomic clocks and digital atomic clocks, though there is nothing radioactive in them. They are merely radio-synchronised from a government atomic clock.
    radio-synched clocks for more details and information on where to buy them
  9. From a signal PBS embeds in its TV broadcasts. This is how VCRs (Videocassette Recorders) can get the time automatically.
  10. From the CBC (Canadian Broadcasting Corporation) radio time signal each day at 10 AM on the FM broadcast stations.
  11. From a signal broadcast on the AC (Alternating Current) power, put here by the utility company.
  12. From your TV Station broadcast channel guide.

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