Kuphatikiza pa tcp/ip, pali njira zambiri zolumikizira nthawi. Zina mwa izo zimangofunika lamya yanthawi zonse, pomwe zina zimafuna zida zamagetsi zokwera mtengo, zosowa komanso zodziwika bwino. Zomangamanga zazikulu zamakina olumikizirana nthawi zikuphatikiza zowonera, mabungwe aboma, ma wayilesi, magulu a nyenyezi a satellite ndi zina zambiri.
Lero ndikuwuzani momwe kulumikizana kwa nthawi kumagwirira ntchito popanda intaneti komanso momwe mungapangire seva ya "satellite" NTP ndi manja anu.
Kuwulutsa kwawayilesi wa Shortwave
Ku United States, NIST imatumiza nthawi yeniyeni ndi ma frequency pa 2.5, 5, 10, 15 ndi 20 MHz mafunde a wailesi kuchokera ku WWVH ku Fort Collins, Colorado, ndi pa 2.5, 5, 10 ndi 15 MHz kuchokera ku WWVH ku Kauai. . Khodi ya nthawi imatumizidwa pakapita mphindi 60 pa 1 bps. pogwiritsa ntchito pulse width modulation pa 100 Hz subcarrier.
National Research Council (NRC) yaku Canada imagawira zambiri za nthawi ndi ma frequency pa 3.33, 7.85 ndi 14.67 MHz kuchokera ku CHU ku Ottawa, Ontario.
Mawonekedwe owulutsa a WWVH
Kufalikira kwa ma Signal kuchokera ku mawayilesi afupiafupi kumachitika ndi kuwunikira kuchokera kumtunda kwa ionosphere. Kutumiza kwa siginecha kumatha kulandiridwa patali, koma kulondola kwanthawi kuli pamadongosolo a millisecond imodzi.
Muyezo wapano wa NTPv4 umaphatikizapo ma driver amawu a WWV, WWVH ndi CHU.
Kuwulutsa kwa wailesi ya Longwave
NIST imatumizanso nthawi yeniyeni komanso mafupipafupi pa wailesi yakutali pa 60 kHz kuchokera ku Boulder, Colorado. Palinso masiteshoni ena omwe amatumiza zizindikiro za nthawi pamafunde aatali.
Zizindikiro zoyimbira ndi malo
pafupipafupi (kHz)
Mphamvu (kW)
WWVB Fort Collins, Colorado, USA
60
50
DCF77 Mainflingen, Germany
77.5
30
MSF Rugby, United Kingdom
60>
50
HBG Prangins, Switzerland
75
20
JJY Fukushima, Japan
40
50
JJY Saga, Japan
60
50
Low Frequency Standard Time Stations
Khodi yanthawiyo imatumizidwa pakapita mphindi 60 pa 1 bps, monga mawayilesi afupikitsa. Mawonekedwe otumizira deta amafanananso ndi miyezo yonse iwiri. Chizindikirocho chimafalikira kudzera m'magulu apansi a ionosphere, omwe amakhala osasunthika ndipo amakhala ndi zosiyana zodziwikiratu za tsiku ndi tsiku. Chifukwa cha kulosera kwa chilengedwe, kulondola kumawonjezeka kufika pa 50 μs.
WWVB kuwulutsa mtundu
Geostationary operational Environmental satellite
Ku US, NIST imatumizanso nthawi yolondola komanso pafupipafupi pafupifupi 468 MHz kuchokera ku Geostationary Operational Environmental Satellites (GOES). Khodi ya nthawi imasinthana ndi mauthenga omwe amagwiritsidwa ntchito poyesa masensa akutali. Zimapangidwa ndi ma 60 BCD nibbles omwe amafalitsidwa pakadutsa 30 s. Zambiri zamakhodi anthawi ndizofanana ndi ntchito zapadziko lapansi.
Machitidwe oyika dziko lonse lapansi
Dipatimenti ya Chitetezo ku United States imagwiritsa ntchito GPS pakuyenda bwino pamtunda, nyanja ndi mlengalenga. Dongosololi limapereka kufalikira kwapadziko lonse lapansi kwa maola 24 pogwiritsa ntchito gulu la nyenyezi la ma satelayiti mumayendedwe a maola 12 omwe amatsatiridwa ndi 55 °.
Gulu loyambirira la ma satelayiti 24 lidakulitsidwa kukhala ma satelayiti 31 mosinthika mosiyanasiyana kotero kuti ma satelayiti osachepera 6 amakhala akuwoneka nthawi zonse, ndipo ma satelayiti 8 kapena kupitilira apo akuwoneka padziko lonse lapansi.
Ntchito zofanana ndi GPS zikugwiritsidwa ntchito kapena kukonzedwa ndi mayiko ena. Russian GLONASS yakhala ikugwira ntchito kwa zaka khumi ndi ziwiri, ngati mungawerenge kuyambira pa Seputembara 2, 2010, pomwe ma satelayiti onse adawonjezedwa mpaka 26 - kuwundanako kudagwiritsidwa ntchito kuti kuphimba dziko lonse lapansi.
Ma satellites a GPS padziko lonse lapansi.
European Union's satellite navigation system imatchedwa Galileo. Zinkayembekezeka kuti Galileo ayamba kugwira ntchito mu 2014-2016, pamene ma satelayiti onse 30 omwe anakonzedwa adzawululidwe mu orbit.
Palinso Chinese "Beidou", kutanthauza "nyangumi". Gulu la nyenyezi 16 linayambika kugwira ntchito zamalonda pa Disembala 27, 2012, ngati dongosolo loyika zigawo. Zakonzedwa kuti dongosololi lifike pofika 2020. Lero chabe, ndatuluka pa Habré , za kukhazikitsidwa bwino kwa satellite ya dongosolo lino.
Masamu ozindikira ma coordinates pogwiritsa ntchito SRNS
Kodi GPS/GLONASS navigator pa foni yanu yam'manja imadziwa bwanji malo omwe ali molondola chonchi pogwiritsa ntchito njira yolumikizirana ndi wailesi (SRNS)? Kuti mumvetse mfundo yowerengera, muyenera kukumbukira stereometry ndi algebra kusukulu ya sekondale, kapena sukulu ya physics ndi masamu.
Setilaiti iliyonse imauza wolandira nthawi yeniyeni. Satellite ili ndi wotchi ya atomiki choncho ikhoza kudaliridwa. Podziwa liwiro la kuwala, sikovuta kudziwa utali wa dera lomwe lili pamwamba pomwe satelayiti ili. Gawo lomweli, polumikizana ndi Dziko Lapansi, limapanga bwalo pomwe wolandila GPS / Glonass amakhala.
Chizindikirocho chikafika kuchokera ku ma satelayiti awiri, tili kale ndi mayendedwe a Dziko Lapansi ndi magawo awiri, omwe amapereka mfundo ziwiri zokha pa bwalo. Gawo la satelayiti yachitatu liyenera kugwera mu imodzi mwa mfundo ziwirizi, pomaliza ndikudziwitsanso zomwe wolandila.
M'malo mwake, ngakhale kuchokera ku ma satelayiti awiri, kutengera umboni wosalunjika, munthu amatha kumvetsetsa kuti ndi mfundo ziti zomwe zili pafupi ndi chowonadi, ndipo ma aligorivimu amakono oyenda panyanja amatha kuthana ndi ntchitoyi. Nanga n’cifukwa ciani tifunika satellite yachinayi?
Kudziwa malo pogwiritsa ntchito nyenyezi za satellite.
N'zosavuta kuona kuti mu chithunzi chodziwika bwino ichi pali ma nuances ambiri omwe kulondola kwa mawerengedwe kumadalira. Nthawi yolandila mwina ndiye gwero lodziwika bwino la zolakwika. Kuti chilichonse chizigwira ntchito momwe ziyenera kukhalira, nthawi yolandila GPS / Glonass iyenera kulumikizidwa ndi nthawi ya satellite. Popanda izi, cholakwikacho chikanakhala ∓ 100 zikwi makilomita.
Kuchokera pamapangidwe a liwiro, nthawi ndi mtunda S = v * t timapeza equation yoyambira yotumizira chizindikiro cha SRNS. Mtunda wopita ku satellite ndi wofanana ndi kuchuluka kwa liwiro la kuwala komanso kusiyana kwa nthawi pa satelayiti ndi wolandila.
Izi makamaka chifukwa chakuti ngakhale zitatha kugwirizanitsa, timadziwa nthawi tpr pa wolandira ndi digiri yolondola yolondola. Pakati pa nthawi yeniyeni ndi tpr padzakhala nthawi zonse Δt, chifukwa chomwe cholakwika chowerengera chimakhala chosavomerezeka. Ndi chifukwa chake muyenera wachinayi satellite.
Kuti tipeze zifukwa zomveka bwino zamasamu pakufunika kwa ma satelayiti anayi, tipanga dongosolo la equation.
Kuti mudziwe zinayi zosadziwika x, y, z, ndi Δt, chiwerengero cha zowonera chiyenera kukhala chofanana kapena chachikulu kuposa chiwerengero cha zosadziwika. Ichi ndi chikhalidwe chofunikira koma chosakwanira. Ngati matrix a equation wamba atakhala amodzi, dongosolo la equation silikhala ndi yankho.
Sitiyeneranso kuyiwala za Special Theory of Relativity ndi zotsatira za relativistic ndi kufutukuka kwa nthawi pa mawotchi a satellite a atomiki okhudzana ndi pansi.
Ngati tikuganiza kuti satellite ikuyenda mozungulira pa liwiro la 14 km / h, ndiye kuti timapeza nthawi yowonjezera pafupifupi 7 μs (microseconds). Kumbali ina, zotsatira za relativistic za General Theory of Relativity zimagwira ntchito.
Mfundo yake ndi iyi: ma satellites mu orbit ali patali kwambiri ndi Dziko Lapansi, pomwe kupindika kwa nthawi yopitilira nthawi kumakhala kochepa kuposa padziko lapansi chifukwa cha kuchuluka kwa dziko lapansi. Malinga ndi relativity wamba, mawotchi omwe ali pafupi ndi chinthu chachikulu amawonekera pang'onopang'ono kusiyana ndi omwe ali kutali ndi chinthucho.
- G ndiye mphamvu yokoka yosasintha;
- M ndi kulemera kwa chinthu, pamenepa dziko lapansi;
- r ndi mtunda kuchokera pakati pa Dziko Lapansi kupita ku satellite;
- c ndi liwiro la kuwala.
Kuwerengera pogwiritsa ntchito fomulayi kumapereka kukulitsa nthawi kwa 45 μs pa satellite. Total -7μs +45μs = 38μs bwino - zotsatira za STR ndi GTR.
Muzoyika za SRNS, kuchedwa kwa ionospheric ndi tropospheric kuyeneranso kuganiziridwa. Kuphatikiza apo, kuwongolera kwa 46 ns kumachitika chifukwa cha 0.02 eccentricity ya orbit ya GPS satellites.
Kutha kulandira ma siginecha nthawi imodzi kuchokera ku ma satellites opitilira anayi a GPS / GLONASS kumakupatsani mwayi wowonjezera kulondola kwazomwe zimagwirizanitsa wolandila. Izi zimatheka chifukwa chakuti woyendetsa sitimayo amathetsa dongosolo la ma equation anayi ndi zinayi zosadziwika kuchuluka kwa nthawi ndipo amatenga mtengo wapakati, kuonjezera kulondola kwa chiwerengero chomaliza molingana ndi malamulo a masamu masamu.
Momwe mungasinthire seva ya NTP Stratum 1 kudzera pa satellite
Kuti mukhazikitse seva yanthawi yapamwamba, mumangofunika GPSD, NTP ndi cholandila GPS chokhala ndi 1PPS (kugunda kumodzi pamphindikati).
1. Ikani gpsd ndi ntpd, kapena gpsd ndi chronyd. Mtundu wa GPSD uyenera kukhala ≥ 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. Lumikizani cholandila GPS ndi chithandizo cha PPS ku serial RS232 kapena doko la USB.
Wolandila wotchipa wokhazikika wa GPS sangagwire ntchito; Mungafunike kufufuza pang'ono kuti mupeze yoyenera.
3. Onetsetsani kuti chipangizochi chikutulutsadi PPS, kuti muchite izi, yang'anani padoko ndi gpsmon.
4. Tsegulani fayilo ya /etc/conf.d/gpsd ndikusintha mzere wotsatirawu.
Bwerezerani
GPSD_OPTIONS=""kuti zikhale
GPSD_OPTIONS="-n"Kusinthaku ndikofunikira kuti gpsd iyambe kufufuza magwero a SRNS poyambitsa.
5. Yambitsani kapena yambitsaninso gpsd.
(1:110)$ sudo /etc/init.d/gpsd start
(1:111)$ sudo /etc/init.d/gpsd restart
Pakugawa ndi systemd, gwiritsani ntchito lamulo loyenera la systemctl.
6. Onani kutulutsa kwa console kwa lamulo la cgps.
Muyenera kuwonetsetsa kuti deta yalandilidwa molondola kuchokera ku ma satelayiti. Konsoni iyenera kukhala ndi zofanana ndi fanizo.
Kutulutsa kwa lamulo la cgps console.
7. Yakwana nthawi yoti musinthe fayilo ya /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
Cholowa chapamwamba cha NTP0 chikuwonetsa gwero lanthawi zonse lomwe likupezeka pafupifupi pazida zonse za GPS. Kulowa pansi kwa NTP1 kumatanthawuza gwero lolondola kwambiri la PPS.
8. Yambitsaninso ntpd.
(1:112)$ sudo /etc/init.d/ntpd restart
Pakugawa ndi systemd, gwiritsani ntchito lamulo la systemctl.
$ sudo systemctl kuyambitsanso ntp
Zogwiritsidwa ntchito
- David L Mills Network Time Protocol Padziko Lapansi ndi Mumlengalenga, Chachiwiri.
Source: www.habr.com