Ngaphezu kwe-tcp/ip, ziningi izindlela zokuvumelanisa isikhathi. Ezinye zazo zidinga ucingo oluvamile kuphela, kanti ezinye zidinga imishini kagesi ebizayo, engavamile futhi ebucayi. Ingqalasizinda ebanzi yezinhlelo zokuvumelanisa isikhathi ihlanganisa izindawo zokubuka izinto, izikhungo zikahulumeni, iziteshi zomsakazo, imilaza yesathelayithi nokunye okuningi.
Namuhla ngizokutshela ukuthi ukuvumelanisa isikhathi kusebenza kanjani ngaphandle kwe-inthanethi nokuthi ungayenza kanjani iseva ye-NTP "ye-satellite" ngezandla zakho.
Ukusakazwa komsakazo we-Shortwave
E-United States, i-NIST idlulisa isikhathi esinembile nemvamisa ku-2.5, 5, 10, 15 kanye namagagasi omsakazo we-20 MHz ukusuka ku-WWVH e-Fort Collins, Colorado, naku-2.5, 5, 10 kanye no-15 MHz ukusuka ku-WWVH e-Kauai. Isifunda sase-Hawaii . Ikhodi yesikhathi idluliselwa ngezikhawu zesekhondi ezingama-60 ku-1 bps. usebenzisa ukuguquguquka kobubanzi be-pulse kusithwali esingaphansi esingu-100 Hz.
I-National Research Council (NRC) yase-Canada isabalalisa ulwazi lwesikhathi nemvamisa ku-3.33, 7.85 kanye no-14.67 MHz kusukela ku-CHU e-Ottawa, Ontario.
Ifomethi yokusakaza i-WWVH
Ukusakazwa kwesignali kusuka eziteshini zamagagasi amafushane kuvame ukuvela ngokubonakala kusuka ezingqimbeni ezingaphezulu ze-ionosphere. Ukudluliswa kwamasignali kungatholwa ngokuhamba kwamabanga amade, kodwa ukunemba kwesikhathi kukulandelana kwe-millisecond eyodwa.
Izinga lamanje le-NTPv4 lihlanganisa izishayeli zomsindo ze-WWV, WWVH ne-CHU.
Ukusakaza emsakazweni iLongwave
I-NIST iphinde idlulise isikhathi esinembayo nemvamisa ngomsakazo we-longwave ku-60 kHz ukusuka e-Boulder, Colorado. Kunezinye iziteshi ezidlulisa izimpawu zesikhathi kumagagasi amade.
Izimpawu zezingcingo nendawo
Imvamisa (kHz)
Amandla (kW)
WWVB Fort Collins, Colorado, USA
60
50
I-DCF77 Mainflingen, Germany
77.5
30
I-MSF Rugby, United Kingdom
60>
50
I-HBG Prangins, eSwitzerland
75
20
JJY Fukushima, Japan
40
50
I-JJY Saga, Japan
60
50
Iziteshi Zesikhathi Ezijwayelekile Eziphansi Ezivamile
Ikhodi yesikhathi idluliselwa ngezikhawu ezingamasekhondi angu-60 ngo-1 bps, njengeziteshi ze-shortwave. Amafomethi okudlulisa idatha nawo ayafana kuwo womabili amazinga. Isignali isakazeka ngezingqimba ezingezansi ze-ionosphere, ezinzile ngokuqhathaniswa futhi ezinokuhlukahluka okubikezelwayo kwansuku zonke kokuphakama. Ngenxa yalokhu kubikezelwa kwendawo ebonakalayo, ukunemba kukhuphuka kube ngu-50 μs.
Ifomethi yokusakaza ye-WWVB
I-Geostationary yokusebenza kwesathelayithi yezemvelo
E-US, i-NIST iphinda idlulise idatha enembile yesikhathi nemvamisa cishe ku-468 MHz ukusuka kumaSathelayithi e-Geostationary Operational Environmental (GOES). Ikhodi yesikhathi iyashintshana nemilayezo esetshenziselwa ukuvota izinzwa ezikude. Iqukethe 60 BCD nibbles ngocansi at 30 s izikhawu. Ulwazi lwekhodi yesikhathi lufana nezinsizakalo zasemhlabeni.
Amasistimu wokumisa umhlaba
UMnyango Wezokuvikela wase-US usebenzisa i-GPS ukuze uthole ukuzulazula okunembile emhlabeni, olwandle nasemoyeni. Lolu hlelo luhlinzeka ngembulunga yonke amahora angama-24 kusetshenziswa umlaza wamasathelayithi emigudwini yamahora ayi-12 ethambekele ku-55°.
Umlaza wokuqala wamasathelayithi angama-24 wanwetshwa waba ngamasathelayithi angama-31 ngendlela ehlukahlukene ukuze okungenani amasathelayithi ayi-6 ahlale ebonakala, futhi amasathelayithi ayi-8 noma ngaphezulu abukwa emhlabeni wonke.
Amasevisi afana ne-GPS asetshenziswa noma ahlelwa ngamanye amazwe. I-GLONASS yaseRussia isisebenze iminyaka eyishumi nambili, ibala kusukela ngoSepthemba 2, 2010, lapho inani eliphelele lamasathelayithi lenyuswa laya ku-26 - umlaza wasetshenziswa ngokugcwele ukumboza umhlaba ngokuphelele.
Amasathelayithi e-GPS emhlabeni jikelele.
Uhlelo lwe-European Union lokuzulazula ngesathelayithi lubizwa ngeGalileo. Bekulindeleke ukuthi i-Galileo iqale ukusebenza ngo-2014-2016, lapho wonke amasathelayithi ahleliwe angu-30 azokwethulwa ku-orbit.
Kukhona negama lesiShayina elithi “Beidou”, elisho “umkhomo”. Umlaza wamasathelayithi ayi-16 wethulwa ukusebenza kwezohwebo ngoDisemba 27, 2012, njengohlelo lokuma kwesifunda. Kuhlelwe ukuthi uhlelo luzofinyelela umthamo ogcwele ngo-2020. Namuhla nje, ngiphume ngo-Habré , mayelana nokwethulwa ngempumelelo kwesathelayithi yalolu hlelo.
Izibalo zokunquma izixhumanisi kusetshenziswa i-SRNS
Ingabe itilosi ye-GPS/GLONASS ku-smartphone yakho inquma kanjani indawo ngokunemba okunjalo kusetshenziswa isistimu yokuxhumana ngokuzulazula komsakazo (SRNS)? Ukuze uqonde isimiso sokubala, udinga ukukhumbula i-stereometry ne-algebra esikoleni esiphakeme, noma esikoleni se-physics nezibalo.
Isathelayithi ngayinye itshela umamukeli isikhathi esiqondile. Isathelayithi inewashi le-athomu ngakho-ke ingathenjwa. Ukwazi ijubane lokukhanya, akunzima ukunquma indawo engaba yindilinga endaweni lapho isathelayithi itholakala khona. Le mbulunga efanayo, lapho ithintana nomhlaba, yenza isiyingi lapho isamukeli se-GPS / Glonass sikhona.
Lapho isignali ifika kumasathelayithi amabili, sesivele sinempambano yoMhlaba kanye nezinhlaka ezimbili, ezinikeza amaphuzu amabili kuphela kumbuthano. I-Sphere yesathelayithi yesithathu kufanele iwele kwelinye lala maphuzu amabili, ekugcineni inqume izixhumanisi zomamukeli.
Empeleni, ngisho nakumasathelayithi amabili, ngokusekelwe ebufakazini obungaqondile, umuntu angaqonda ukuthi yimaphi amaphuzu amabili aseduze neqiniso, futhi ama-algorithms wesofthiwe wokuzulazula wesimanje angabhekana nalo msebenzi. Kungani-ke sidinga isathelayithi yesine?
Ukunquma indawo kusetshenziswa umlaza wesathelayithi.
Kulula ukubona ukuthi kulesi sithombe esihle kunama-nuances amaningi lapho ukunemba kwezibalo kuncike khona. Isikhathi somamukeli mhlawumbe siwumthombo wephutha osobala kakhulu. Ukuze yonke into isebenze ngendlela efanele, isikhathi somamukeli we-GPS/Glonass kufanele sivunyelaniswe nesikhathi sesathelayithi. Ngaphandle kwalokhu, iphutha kungaba ∓ 100 ayizinkulungwane km.
Kusuka kufomula yesivinini, isikhathi nebanga S = v*t sithola isibalo esiyisisekelo sokudlulisa isignali ye-SRNS. Ibanga lesathelayithi lilingana nomkhiqizo wejubane lokukhanya kanye nomehluko wesikhathi kwisathelayithi nesamukeli.
Lokhu kubangelwa kakhulu ukuthi ngisho nangemva kwakho konke ukuvumelanisa, siyasazi isikhathi tpr kumamukeli ngezinga elanele lokunemba. Phakathi kwesikhathi sangempela kanye ne-tpr kuzohlala kukhona u-Δt, ngenxa yokuthi iphutha lokubala lingamukeleki. Yingakho udinga okwesine isathelayithi.
Ukuze uthole isizathu esicacile sezibalo sesidingo samasathelayithi amane, sizokwakha uhlelo lwezibalo.
Ukuze unqume okungaziwa okune okungu-x, y, z, kanye no-Δt, inani lokubhekwa kufanele lilingane noma libe likhulu kunenombolo yokungaziwa. Lesi yisimo esidingekayo kodwa esinganele. Uma i-matrix yezibalo ezivamile iphenduka ibe munye, isistimu yezibalo ngeke ibe nesixazululo.
Akufanele futhi sikhohlwe nge-Special Theory of Relativity kanye nemiphumela ehlobene nokunwetshwa kwesikhathi kumawashi e-athomu esethelayithi ahlobene nalawo aphansi.
Uma sicabanga ukuthi i-satellite ihamba ku-orbit ngesivinini esingamakhilomitha ayizinkulungwane ezingu-14 / h, khona-ke sithola ukunwetshwa kwesikhathi okungaba ngu-7 μs (ama-microseconds). Ngakolunye uhlangothi, imiphumela ye-relativistic ye-General Theory of Relativity iyasebenza.
Iphuzu liwukuthi: amasathelayithi ku-orbit aqhelelene kakhulu noMhlaba, lapho ukugoba kokuqhubeka kwesikhathi sesikhala kungaphansi komhlaba ngenxa yobunzima boMhlaba. Ngokusho kokuhlobana okujwayelekile, amawashi aseduze nento enkulu azobonakala ehamba kancane kunalawo aqhelelene nayo.
- U-G yi-gravitational constant;
- M yinqwaba yento, kulokhu umhlaba;
- r yibanga ukusuka enkabeni yoMhlaba ukuya kwisathelayithi;
- c ijubane lokukhanya.
Ukubala kusetshenziswa le fomula kunikeza ukunwetshwa kwesikhathi okungama-45 μs kusathelayithi. Isamba -7μs +45μs = 38μs ibhalansi - imiphumela ye-STR ne-GTR.
Kuzinhlelo zokusebenza zokubeka i-SRNS, ukubambezeleka kwe-ionospheric ne-tropospheric kufanele futhi kucatshangelwe. Ngaphezu kwalokho, ukulungiswa kwe-46 ns kungenxa ye-eccentricity engu-0.02 ye-orbit yamasathelayithi e-GPS.
Ikhono lokwamukela amasiginali ngasikhathi sinye kusuka kumasathelayithi e-GPS / GLONASS angaphezu kwamane likuvumela ukuthi uqhubeke nokukhulisa ukunemba kokunquma izixhumanisi zomamukeli. Lokhu kufinyelelwa ngenxa yokuthi itilosi ixazulula uhlelo lwezibalo ezine ezinezinto ezine ezingaziwa inombolo yezikhathi futhi ithatha inani elimaphakathi, ikhulisa ukunemba kwesilinganiso sokugcina ngokuya ngemithetho yezibalo zezibalo.
Uyimisa kanjani iseva ye-NTP i-Stratum 1 ngoxhumano lwesathelayithi
Ukuze usethe iseva yesikhathi yekhwalithi ephezulu, udinga kuphela i-GPSD, i-NTP kanye nesamukeli se-GPS esine-1PPS (ishayela elilodwa ngomzuzwana).
1. Faka i-gpsd ne-ntpd, noma i-gpsd ne-chronyd. Inguqulo ye-GPSD kufanele ibe ngu-≥ 3.20
(1:1109)$ sudo emerge -av gpsd chrony
Local copy of remote index is up-to-date and will be used.
Calculating dependencies... done!
[binary N ] net-misc/pps-tools-0.0.20120407::gentoo 31 KiB
[binary N ] net-misc/chrony-3.5-r2::gentoo USE="adns caps cmdmon ipv6 ntp phc readline refclock rtc seccomp (-html) -libedit -pps (-selinux)" 246 KiB
[binary N ] sci-geosciences/gpsd-3.17-r3:0/23::gentoo USE="X bluetooth cxx dbus ipv6 ncurses python shm sockets udev usb -debug -latency-timing -ntp -qt5 -static -test" GPSD_PROTOCOLS="aivdm ashtech earthmate evermore fv18 garmin garmintxt gpsclock isync itrax mtk3301 navcom ntrip oceanserver oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 tnt tripmate tsip ublox -fury -geostar -nmea0183 -nmea2000 -passthrough" PYTHON_TARGETS="python2_7" 999 KiB
Total: 3 packages (3 new, 3 binaries), Size of downloads: 1275 KiB
Would you like to merge these packages? [Yes/No]2. Xhuma isamukeli se-GPS ngosekelo lwe-PPS kuchungechunge lwe-RS232 noma imbobo ye-USB.
Isamukeli se-GPS esishibhile esivamile ngeke sisebenze; Kungase kudingeke wenze ukusesha okuncane ukuze uthole okulungile.
3. Qiniseka ukuthi idivayisi iyikhipha ngempela i-PPS; ukwenza lokhu, hlola ichweba nge-gpsmon utility.
4. Vula ifayela /etc/conf.d/gpsd bese uhlela umugqa olandelayo.
Faka esikhundleni
GPSD_OPTIONS=""ukuze kube
GPSD_OPTIONS="-n"Lolu shintsho luyadingeka ukuze i-gpsd iqale ngokushesha ukucinga imithombo ye-SRNS lapho iqala.
5. Qala noma qala kabusha i-gpsd.
(1:110)$ sudo /etc/init.d/gpsd start
(1:111)$ sudo /etc/init.d/gpsd restart
Ngokusatshalaliswa nge-systemd, sebenzisa umyalo we-systemctl ofanele.
6. Hlola ukuphuma kwekhonsoli komyalo we-cgps.
Udinga ukwenza isiqiniseko sokuthi idatha itholwa ngendlela efanele kumasathelayithi. I-console kufanele ibe nento efanayo nomfanekiso.
Okukhipha umyalo we-cgps console.
7. Yisikhathi sokuhlela ifayela /etc/ntp.conf.
# GPS Serial data reference (NTP0)
server 127.127.28.0
fudge 127.127.28.0 time1 0.9999 refid GPS
# GPS PPS reference (NTP1)
server 127.127.28.1 prefer
fudge 127.127.28.1 refid PPS
Okufakiwe okuphezulu kwe-NTP0 kukhombisa umthombo wesikhathi otholakala cishe kuwo wonke amadivayisi we-GPS. Okufakiwe okungezansi kwe-NTP1 kuchaza umthombo we-PPS onembe kakhulu.
8. Qala kabusha i-ntpd.
(1:112)$ sudo /etc/init.d/ntpd restart
Ngokusatshalaliswa nge-systemd, sebenzisa umyalo we-systemctl.
$ sudo systemctl qala kabusha i-ntp
Izinto ezisetshenzisiwe
- UDavid L Mills I-Network Time Protocol Emhlabeni Nasemkhathini,Uhlelo Lwesibili.
Source: www.habr.com