Ntxiv rau tcp / ip, muaj ntau txoj hauv kev los synchronize lub sijhawm. Qee tus ntawm lawv tsuas yog xav tau lub xov tooj tsis tu ncua, thaum lwm tus xav tau cov khoom siv hluav taws xob kim, tsis tshua muaj thiab rhiab heev. Cov txheej txheem dav dav ntawm lub sijhawm synchronization systems suav nrog kev soj ntsuam, tsoomfwv cov chaw, xov tooj cua, satellite constellations thiab ntau ntxiv.
Hnub no kuv yuav qhia koj tias lub sijhawm synchronization ua haujlwm li cas yam tsis muaj Is Taws Nem thiab yuav ua li cas thiaj li ua "satellite" NTP server nrog koj tus kheej tes.
Xov tooj cua Shortwave tshaj tawm
Hauv Tebchaws Meskas, NIST xa cov sijhawm thiab zaus ntawm 2.5, 5, 10, 15 thiab 20 MHz xov tooj cua los ntawm WWVH hauv Fort Collins, Colorado, thiab ntawm 2.5, 5, 10 thiab 15 MHz los ntawm WWVH hauv Kauai. Xeev Hawaii. . Lub sijhawm code kis ntawm 60 thib ob ntu ntawm 1 bps. siv pulse width modulation ntawm 100 Hz subcarrier.
Lub National Research Council (NRC) ntawm Canada faib cov ntaub ntawv sijhawm thiab zaus ntawm 3.33, 7.85 thiab 14.67 MHz los ntawm CHU hauv Ottawa, Ontario.
Broadcast format WWVH
Cov teeb liab nthuav tawm los ntawm cov chaw nres tsheb luv luv feem ntau tshwm sim los ntawm kev xav los ntawm cov khaubncaws sab nraud povtseg ntawm ionosphere. Cov teeb liab kis tau tuaj yeem tau txais nyob deb, tab sis lub sijhawm raug yog nyob ntawm qhov kev txiav txim ntawm ib millisecond.
Tus qauv NTPv4 tam sim no suav nrog cov tsav tsheb rau WWV, WWVH thiab CHU.
Longwave xov tooj cua tshaj tawm
NIST tseem xa cov sijhawm thiab zaus tshaj xov tooj cua ntev ntawm 60 kHz los ntawm Boulder, Colorado. Muaj lwm qhov chaw xa xov xwm lub sijhawm ntawm nthwv dej ntev.
Hu rau cov paib thiab qhov chaw
Ntau zaus (kHz)
Lub zog (kW)
WWB Fort Collins, Colorado, USA
60
50
DCF77 Mainflingen, Lub teb chaws Yelemees
77.5
30
MSF Rugby, United Kingdom
60>
50
HBG Prangins, Switzerland
75
20
JJY Fukushima, Nyiv
40
50
JJY Saga, Nyiv
60
50
Tsawg zaus Standard Time Stations
Lub sijhawm code kis tau nyob rau hauv 60-thib ob ntu ntawm 1 bps, ib yam li cov chaw nres tsheb luv. Cov ntaub ntawv kis tau tus mob kuj zoo ib yam rau ob tus qauv. Lub teeb liab propagates los ntawm cov khaubncaws sab nraud povtseg ntawm lub ionosphere, uas yog ib tug ruaj khov thiab muaj kwv yees li niaj hnub variations nyob rau hauv qhov siab. Ua tsaug rau qhov kev kwv yees ntawm lub cev ib puag ncig, qhov tseeb nce mus rau 50 ΞΌs.
WWB broadcast format
Geostationary ua haujlwm ib puag ncig satellite
Hauv Teb Chaws Asmeskas, NIST tseem xa cov ntaub ntawv sijhawm thiab zaus ntawm kwv yees li 468 MHz los ntawm Geostationary Operational Environmental Satellites (GOES). Lub sij hawm code hloov nrog cov lus siv los soj ntsuam cov chaw taws teeb sensors. Nws muaj 60 BCD nibbles kis ntawm 30 s ib ntus. Lub sij hawm code cov ntaub ntawv zoo ib yam li cov kev pabcuam hauv av.
Ntiaj teb no positioning systems
Lub Tsev Haujlwm Saib Xyuas Kev Tiv Thaiv Tebchaws Meskas siv GPS rau kev taug kev hauv av, hiav txwv thiab huab cua. Lub kaw lus muab 24-teev kev pabcuam ntawm lub ntiaj teb siv lub hnub qub ntawm satellites hauv 12-teev orbits inclined ntawm 55 Β°.
Tus thawj constellation ntawm 24 satellites tau nthuav mus rau 31 satellites nyob rau hauv ib tug heterogeneous configuration kom tsawg kawg yog 6 satellites ib txwm nyob rau hauv saib, thiab 8 los yog ntau tshaj satellites nyob rau hauv view ntawm feem ntau ntawm lub ntiaj teb no.
Cov kev pabcuam zoo ib yam li GPS tau ua haujlwm lossis npaj los ntawm lwm lub tebchaws. Lavxias GLONASS tau ua haujlwm rau kaum xyoo, yog tias koj suav txij lub Cuaj Hlis 2, 2010, thaum tag nrho cov satellites tau nce mus rau 26 - lub hnub qub tau xa mus rau tag nrho lub ntiaj teb.
GPS satellites thoob plaws ntiaj teb.
European Union lub satellite navigation system hu ua Galileo. Nws tau xav tias Galileo yuav pib ua haujlwm hauv 2014-2016, thaum tag nrho 30 lub satellites npaj yuav raug xa mus rau hauv orbit, tab sis txij li xyoo 2018, Galileo satellite constellation tsis tau mus txog qhov xav tau ntawm satellites.
Kuj tseem muaj Suav "Beidou", uas txhais tau tias "whale". Lub constellation ntawm 16 satellites tau pib ua lag luam thaum lub Kaum Ob Hlis 27, 2012, raws li lub cheeb tsam chaw nyob. Nws tau npaj tias qhov system yuav ncav cuag lub peev xwm los ntawm 2020. Tsuas yog hnub no, kuv tuaj tawm ntawm Habre , hais txog kev vam meej ntawm lub satellite ntawm no system.
Kev ua lej ntawm kev txiav txim siab ua haujlwm siv SRNS
Lub GPS / GLONASS navigator ntawm koj lub xov tooj smartphone li cas txiav txim siab qhov chaw nrog qhov tseeb siv lub xov tooj cua navigation kev sib txuas lus (SRNS) li cas? Yuav kom nkag siab txog lub hauv paus ntsiab lus ntawm kev suav, koj yuav tsum nco ntsoov stereometry thiab algebra hauv tsev kawm theem siab, lossis tsev kawm ntawv physics thiab lej.
Txhua lub satellite qhia cov neeg txais lub sijhawm. Lub satellite muaj lub moos atomic thiab yog li ntawd tuaj yeem ntseeg tau. Paub qhov ceev ntawm lub teeb, nws tsis yooj yim los txiav txim lub vojvoog ntawm lub kheej kheej ntawm qhov chaw uas lub satellite nyob. Qhov no tib kheej kheej, nyob rau hauv kev sib cuag nrog lub ntiaj teb, tsim ib lub voj voog uas lub GPS / Glonass receiver nyob.
Thaum lub teeb liab tuaj txog ntawm ob lub satellite, peb twb muaj kev sib tshuam ntawm lub ntiaj teb thiab ob lub spheres, uas tsuas yog muab ob lub ntsiab lus ntawm lub voj voog. Lub kheej kheej ntawm lub satellite thib peb yuav tsum zoo siab poob rau hauv ib qho ntawm ob lub ntsiab lus no, thaum kawg txiav txim siab qhov chaw ntawm lub receiver.
Hauv cov ntsiab lus, txawm tias los ntawm ob lub satellites, raws li cov pov thawj tsis ncaj, ib tus tuaj yeem nkag siab qhov twg ntawm ob lub ntsiab lus yog ze rau qhov tseeb, thiab niaj hnub navigation software algorithms tuaj yeem tiv nrog txoj haujlwm no. Vim li cas peb thiaj xav tau lub satellite thib plaub?
Kev txiav txim qhov chaw siv satellite constellation.
Nws yog ib qho yooj yim kom pom tias nyob rau hauv daim duab zoo tagnrho no muaj ntau yam nuances uas qhov tseeb ntawm kev xam nyob ntawm. Lub sijhawm txais yuav yog qhov pom tseeb tshaj plaws ntawm qhov yuam kev. Yuav kom txhua yam ua haujlwm raws li qhov yuav tsum tau ua, GPS / Glonass txais lub sijhawm yuav tsum tau synchronized nrog lub sijhawm satellite. Yog tsis muaj qhov no, qhov yuam kev yuav yog β 100 txhiab km.
Los ntawm cov qauv rau kev ceev, lub sij hawm thiab qhov deb S = v * t peb tau txais cov kab zauv yooj yim rau kev xa cov teeb liab SRNS. Qhov kev ncua deb ntawm lub satellite yog sib npaug rau cov khoom ntawm lub teeb nrawm thiab lub sijhawm sib txawv ntawm lub satellite thiab lub receiver.
Qhov no feem ntau yog vim qhov tseeb tias txawm tias tom qab tag nrho cov synchronizations, peb paub lub sijhawm tpr ntawm lub receiver nrog ib tug txaus degree ntawm qhov tseeb. Nyob nruab nrab ntawm lub sij hawm tseeb thiab tpr yeej ib txwm muaj Ξt, vim qhov kev ua yuam kev suav ua tsis tau. Yog vim li cas koj xav tau plaub satellite.
Rau kev pom tseeb ntawm kev ua lej kom pom tseeb rau qhov xav tau ntawm plaub lub satellites, peb yuav tsim ib qho kev sib npaug.
Txhawm rau txiav txim plaub yam tsis paub x, y, z, thiab Ξt, tus naj npawb ntawm kev soj ntsuam yuav tsum sib npaug los yog ntau dua li tus lej tsis paub. Qhov no yog qhov tsim nyog tab sis tsis txaus. Yog hais tias lub matrix ntawm ib txwm equations hloov tawm los ua ib qho, qhov system ntawm kev sib npaug yuav tsis muaj kev daws teeb meem.
Peb yuav tsum tsis txhob hnov ββββqab txog Kev Tshawb Fawb Tshwj Xeeb ntawm Kev Sib Raug Zoo thiab cov teebmeem kev sib raug zoo nrog lub sijhawm dilation ntawm satellite atomic moos txheeb ze rau hauv av.
Yog hais tias peb xav hais tias lub satellite tsiv nyob rau hauv orbit ntawm ib tug ceev ntawm 14 txhiab km / h, ces peb tau txais ib lub sij hawm dilation ntawm txog 7 ΞΌs (microseconds). Ntawm qhov tod tes, qhov cuam tshuam ntawm kev sib raug zoo ntawm General Theory of Relativity ua haujlwm.
Lub ntsiab lus yog qhov no: satellites nyob rau hauv orbit yog nyob rau hauv ib tug zoo deb ntawm lub ntiaj teb, qhov twg curvature ntawm lub sij hawm nyob rau hauv lub sij hawm txuas ntxiv yog tsawg dua nyob rau hauv lub ntiaj teb nto vim lub ntiaj teb loj. Raws li kev txheeb xyuas dav dav, cov moos nyob ze rau ntawm qhov khoom loj yuav tshwm sim qeeb dua li cov nyob deb ntawm nws.
- G yog qhov gravitational tas li;
- M yog qhov loj ntawm cov khoom, qhov no lub ntiaj teb;
- r yog qhov kev ncua deb ntawm qhov chaw ntawm lub ntiaj teb mus rau lub satellite;
- c yog qhov ceev ntawm lub teeb.
Kev suav siv cov qauv no muab lub sijhawm dilation ntawm 45 ΞΌs ntawm lub satellite. Tag nrho -7ΞΌs +45ΞΌs = 38ΞΌs sib npaug - cuam tshuam ntawm STR thiab GTR.
Hauv SRNS qhov chaw thov, ionospheric thiab tropospheric qeeb yuav tsum tau coj mus rau hauv tus account. Tsis tas li ntawd, 46 ns kho yog vim 0.02 eccentricity ntawm GPS satellites 'orbit.
Lub peev xwm tau txais cov teeb liab ib txhij los ntawm ntau tshaj plaub lub GPS / GLONASS satellites tso cai rau koj ntxiv qhov tseeb ntawm kev txiav txim siab tus txais kev tswj hwm. Qhov no yog ua tiav vim qhov tseeb tias tus navigator daws tau qhov system ntawm plaub qhov sib npaug nrog plaub yam tsis paub tus naj npawb ntawm cov sij hawm thiab siv qhov nruab nrab tus nqi, nce qhov tseeb ntawm qhov kev kwv yees zaum kawg raws li cov cai ntawm kev txheeb xyuas lej.
Yuav ua li cas rau configure NTP server Stratum 1 ntawm satellite kev twb kev txuas
Txhawm rau teeb tsa lub sijhawm ua haujlwm tau zoo, koj tsuas yog xav tau GPSD, NTP thiab GPS txais nrog 1PPS (ib mem tes ib ob) tso zis.
1. Nruab gpsd thiab ntpd, lossis gpsd thiab chronyd. GPSD version yuav tsum yog β₯ 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. Txuas lub receiver GPS nrog PPS kev txhawb nqa rau RS232 serial lossis USB chaw nres nkoj.
Ib tug pheej yig GPS txais yuav tsis ua hauj lwm; Tej zaum koj yuav tau ua ib qho kev tshawb nrhiav me ntsis kom pom qhov zoo.
3. Xyuas kom tseeb tias lub cuab yeej yeej teeb meem PPS; ua li no, xyuas qhov chaw nres nkoj nrog cov khoom siv gpsmon.
4. Qhib cov ntaub ntawv /etc/conf.d/gpsd thiab kho cov kab hauv qab no.
Hloov
GPSD_OPTIONS=""kom nws ua
GPSD_OPTIONS="-n"Qhov kev hloov pauv no yuav tsum tau ua kom gpsd tam sim ntawd pib tshawb nrhiav SRNS qhov chaw thaum pib.
5. Pib lossis rov pib dua gpsd.
(1:110)$ sudo /etc/init.d/gpsd start
(1:111)$ sudo /etc/init.d/gpsd restart
Rau kev faib khoom nrog systemd, siv cov lus txib tsim nyog systemctl.
6. Tshawb xyuas lub console tso zis ntawm cgps hais kom ua.
Koj yuav tsum xyuas kom meej tias cov ntaub ntawv tau txais raug los ntawm satellites. Lub console yuav tsum muaj qee yam zoo ib yam li cov lus piav qhia.
Tso zis ntawm cgps console hais kom ua.
7. Nws yog lub sijhawm los hloov cov ntaub ntawv /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
Sab saum toj NTP0 nkag qhia txog lub sijhawm thoob ntiaj teb muaj nyob ntawm yuav luag txhua yam khoom siv GPS. NTP1 nkag hauv qab qhia txog qhov tseeb PPS ntau dua.
8. Restart ntpd.
(1:112)$ sudo /etc/init.d/ntpd restart
Rau kev faib khoom nrog systemd, siv cov lus txib systemctl.
$ sudo systemctl rov pib ntp
Cov ntaub ntawv siv
- David L Mills Network Sijhawm raws tu qauv ntawm lub ntiaj teb thiab hauv Chaw, thib ob tsab.
Tau qhov twg los: www.hab.com