Ukongeza kwi-tcp/ip, kukho iindlela ezininzi zokuvumelanisa ixesha. Ezinye zazo zifuna kuphela ifowuni eqhelekileyo, ngelixa ezinye zifuna izixhobo ze-elektroniki ezibizayo, ezinqabileyo nezinovakalelo. Iziseko ezingundoqo zeenkqubo zongqamaniso lwexesha ziquka iindawo zokujonga izinto, amaziko karhulumente, izikhululo zikanomathotholo, iinkwenkwezi zesathelayithi nokunye okuninzi.
Namhlanje ndiza kukuxelela ukuba ulungelelwaniso lwexesha lusebenza njani ngaphandle kwe-Intanethi kunye nendlela yokwenza iseva ye-NTP "yesatellite" ngezandla zakho.
Usasazo lukanomathotholo iShortwave
EUnited States, i-NIST ihambisa ixesha elichanekileyo kunye ne-frequency kwi-2.5, 5, 10, 15 kunye ne-20 MHz amaza erediyo ukusuka kwi-WWVH e-Fort Collins, e-Colorado, kunye ne-2.5, 5, 10 kunye ne-15 MHz ukusuka kwi-WWVH eKauai. . Ikhowudi yexesha ihanjiswa kwii-60 zezihlandlo zesibini kwi-1 bps. usebenzisa ukumodareyitha kobubanzi be-pulse kwi-100 Hz subcarrier.
IBhunga loPhando lweSizwe (i-NRC) yaseCanada isasaza ixesha kunye nolwazi oluphindaphindiweyo kwi-3.33, 7.85 kunye ne-14.67 MHz ukusuka kwi-CHU e-Ottawa, e-Ontario.
Ifomathi yosasazo ye-WWVH
Ukusasazwa komqondiso ukusuka kwizikhululo ze-shortwave ngokuqhelekileyo kwenzeka ngokubonakaliswa ukusuka kumaleko aphezulu e-ionosphere. Ukuhanjiswa kweSiginali kunokufunyanwa kumgama omde, kodwa ukuchaneka kwexesha kukwi-odolo ye-millisecond enye.
Umgangatho wangoku we-NTPv4 uquka abaqhubi be-audio be-WWV, i-WWVH kunye ne-CHU.
Usasazo lukanomathotholo eLongwave
I-NIST ikwasasaza ixesha elichanekileyo kunye nokuphindaphinda kwirediyo ye-longwave kwi-60 kHz ukusuka eBoulder, eColorado. Kukho ezinye izikhululo ezihambisa imiqondiso yexesha kumaza amade.
Iimpawu zokufowuna kunye nendawo
Ukuphindaphinda (kHz)
Amandla (kW)
WWVB Fort Collins, Colorado, USA
60
50
DCF77 Mainflingen, eJamani
77.5
30
Umbhoxo we-MSF, eUnited Kingdom
60>
50
HBG Prangins, eSwitzerland
75
20
JJY Fukushima, eJapan
40
50
UJJY Saga, eJapan
60
50
Izitishi zeXesha eziQhelekileyo eziPhantsi
Ikhowudi yexesha ihanjiswa kwizithuba ze-60-yesibini kwi-1 bps, njengezikhululo ze-shortwave. Iifomathi zothumelo lwedatha nazo ziyafana kuyo yomibini imigangatho. Umqondiso usasaza ngeengqimba ezisezantsi ze-ionosphere, ezizinzile kwaye zineenguqu eziqikelelweyo zokuphakama kwemihla ngemihla. Ngombulelo koku kuqikelelwa kwendalo ebonakalayo, ukuchaneka kunyuka ukuya kuma-50 μs.
Ifomati yosasazo yeWWVB
I-Geostationary yokusebenza kwesathelayithi yokusingqongileyo
E-US, i-NIST ikwathumela ngokuthe ngqo ixesha kunye nedatha rhoqo malunga ne-468 MHz ukusuka kwi-Geostationary Operational Environmental Satellites (GOES). Ikhowudi yexesha litshintshana ngemiyalezo esetyenziselwa ukuvota iinzwa ezikude. Iqukethe i-60 ye-BCD nibbles ehanjiswa ngezithuba ze-30. Ulwazi lwekhowudi yexesha lufana neenkonzo zasemhlabeni.
Iinkqubo zokubeka umhlaba
ISebe lezoKhuselo lase-US lisebenzisa i-GPS ukujonga ngokuthe ngqo emhlabeni, elwandle nasemoyeni. Le nkqubo ibonelela ngokugubungela umhlaba iiyure ezingama-24 kusetyenziswa iqela leenkwenkwezi zesathelayithi kwiindlela ezijikeleza iiyure ezili-12 ezithambekele kuma-55°.
Iqoqo leenkwenkwezi zantlandlolo zesathelayithi ezingama-24 zandiswa zaya kutsho kwiisathelayithi ezingama-31 ngokolungelelwano oluxananazileyo ukuze ubuncinane iisathelayithi ezi-6 zisoloko zibonwa, yaye iisathelayithi ezisi-8 okanye ngaphezulu zibonwa kuninzi lwehlabathi.
Iinkonzo ezifana neGPS ziqhutywa okanye zicwangciswa ngamanye amazwe. I-GLONASS yaseRashiya isebenze iminyaka elishumi elinesibini, ukuba ubala ukususela ngoSeptemba 2, 2010, xa inani elipheleleyo le-satellites lanyuswa ukuya kwi-26 - i-constellation yasasazwa ngokupheleleyo ukugubungela umhlaba ngokupheleleyo.
Iisathelayithi zeGPS kwihlabathi jikelele.
Inkqubo yesathelayithi yeManyano yaseYurophu ibizwa ngokuba yiGalileo. Kwakulindeleke ukuba iGalileo iqalise ukusebenza ngo-2014-2016, xa zonke iisathelayithi ezicwangcisiweyo ze-30 ziza kuqaliswa kwi-orbit.
Kukwakho neTshayina elithi “Beidou”, elithetha “umnenga”. Iqela leenkwenkwezi ezili-16 zesathelayithi zaqaliswa ukuba zisebenze nge-27 kaDisemba, 2012, njengenkqubo yokumisa kwingingqi. Kucwangciswe ukuba inkqubo iya kufikelela kumthamo opheleleyo ngo-2020. Namhlanje nje, ndiphume ngoHabré , malunga nokuqaliswa ngempumelelo kwesathelayithi yale nkqubo.
IMathematika yokumisela ulungelelwaniso kusetyenziswa i-SRNS
Ingaba i-GPS/GLONASS yomqhubi wenqwelomoya kwi-smartphone yakho imisela njani indawo ngokuchaneka okunjalo usebenzisa inkqubo yonxibelelwano lokuhamba ngerediyo (SRNS)? Ukuze uqonde umgaqo wokubala, kufuneka ukhumbule i-sterometry kunye ne-algebra kwisikolo samabanga aphakamileyo, okanye isikolo se-physics kunye nemathematika.
Isathelayithi nganye ixelela umamkeli elona xesha lichanekileyo. Isathelayithi inewotshi yeathom kwaye ngoko inokuthenjwa. Ukwazi isantya sokukhanya, akunzima ukumisela i-radius ye-sphere kumphezulu apho i-satellite ikhona. Kwale ngqukuva, xa idibana noMhlaba, yenza isangqa apho iGPS / iGlonass ifumana isangqa.
Xa umqondiso ufika kwi-satellites ezimbini, sele sine-intersection yomhlaba kunye neengqungquthela ezimbini, ezinika amanqaku amabini kuphela kwisangqa. Inqanaba lesathelayithi yesithathu kufuneka liwele kwelinye lala manqaku mabini, ekugqibeleni limisele ulungelelwaniso lomamkeli.
Ngokomgaqo, nakwii-satellites ezimbini, ngokusekelwe kubungqina obungathanga ngqo, umntu unokuqonda ukuba yeyiphi kula manqaku mabini asondele kwinyani, kwaye i-algorithms yesoftware yokukhangela yanamhlanje inokumelana nalo msebenzi. Kutheni ke ngoko sifuna isathelayithi yesine?
Ukumisela indawo usebenzisa i-satellite constellation.
Kulula ukubona ukuba kulo mfanekiso ochanekileyo kukho ama-nuances amaninzi apho ukuchaneka kwezibalo kuxhomekeke. Ixesha lomamkeli mhlawumbi ngowona mthombo ucacileyo wempazamo. Ukuze yonke into isebenze njengoko kufanele, i-GPS / ixesha lomamkeli we-Glonass kufuneka lidityaniswe nexesha lesathelayithi. Ngaphandle koku, impazamo iya kuba ∓ 100 amawaka eekhilomitha.
Ukususela kwifomula yesantya, ixesha kunye nomgama S = v * t sifumana i-equation eyisiseko yokuhambisa isignali ye-SRNS. Umgama kwisathelayithi ulingana nemveliso yesantya sokukhanya kunye nokwahlukana kwexesha kwisathelayithi kunye nomamkeli.
Oku kubangelwa ikakhulu kwinto yokuba nasemva kwalo lonke ulungelelwaniso, siyalazi ixesha tpr kumamkeli ngeqondo elaneleyo lokuchaneka. Phakathi kwexesha lokwenyani kunye ne-tpr kuyakuhlala kukho Δt, ngenxa yokuba impazamo yokubala ingamkeleki. Yiyo loo nto udinga owesine isathelayithi.
Ukufumana ulungelelwaniso olucacileyo lwemathematika kwimfuno yeesathelayithi ezine, siya kwakha inkqubo yee-equations.
Ukumisela ezine ezingaziwayo x, y, z, kunye Δt, inani lemigqaliselo kufuneka lilingane okanye libe likhulu kunenani lezinto ezingaziwayo. Le yimeko efunekayo kodwa ayanelanga. Ukuba i-matrix ye-equations eqhelekileyo ijika ibe yinto enye, inkqubo yokulinganisa ayiyi kuba nesisombululo.
Akufunekanga silibale malunga neTheory eKhethekileyo yokuNxibelelana kunye neziphumo ezihambelanayo kunye nokwenyuswa kwexesha kwiiwotshi zesathelayithi zeathom xa zithelekiswa nezo zisezantsi.
Ukuba sicinga ukuba i-satellite ihamba kwi-orbit ngesantya se-14 lamawaka km / h, ngoko sifumana ixesha lokunyuswa malunga ne-7 μs (microseconds). Kwelinye icala, iimpembelelo ze-relativistic zeTheory Jikelele yeRelativity ziyasebenza.
Ingongoma yile: iisathelayithi ezikwi-orbit zikumgama omkhulu ukusuka eMhlabeni, apho ukugoba kwesithuba sexesha lesithuba kungaphantsi komphezulu woMhlaba ngenxa yobunzima boMhlaba. Ngokwerelativity jikelele, iiwotshi ezibekwe kufutshane nento enkulu ziya kubonakala zicotha kunezo zikude kuyo.
- U-G ngumxhuzulane ongaguqukiyo;
- M bubunzima bento, kule meko nguMhlaba;
- r ngumgama ukusuka kumbindi woMhlaba ukuya kwisathelayithi;
- c sisantya sokukhanya.
Ukubala usebenzisa le fomula kunika ixesha lokwandiswa kwama-45 μs kwisathelayithi. Iyonke -7μs +45μs = 38μs ibhalansi - iziphumo ze-STR kunye ne-GTR.
Kwizicelo zokubeka i-SRNS, ukulibaziseka kwe-ionospheric kunye ne-tropospheric kufuneka kwakhona kuthathelwe ingqalelo. Ukongeza, izilungiso ze-46 ns zibangelwa yi-0.02 eccentricity ye-orbit ye-satellites ye-GPS.
Ukukwazi ukufumana imiqondiso ngaxeshanye kwiisathelayithi ze-GPS / GLONASS zikuvumela ukuba unyuse ngakumbi ukuchaneka kokumisela ulungelelwaniso lomamkeli. Oku kuphunyezwa ngenxa yokuba umqhubi wenqanawa usombulula inkqubo yee-equations ezine ezineengaziwayo inani lamaxesha kwaye ithatha ixabiso eliphakathi, ukwandisa ukuchaneka koqikelelo lokugqibela ngokwemithetho yezibalo zemathematika.
Uyiqwalasela njani iseva yeNTP iStratum 1 ngoqhagamshelwano lwesatellite
Ukuseta umncedisi wexesha eliphezulu, udinga kuphela i-GPSD, i-NTP kunye ne-GPS receiver kunye ne-1PPS (i-pulse enye ngesekhondi) isiphumo.
1. Faka i-gpsd kunye ne-ntpd, okanye i-gpsd kunye ne-chronyd. Uguqulelo lweGPSD kufuneka lube ≥ 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. Qhagamshela isamkeli seGPS ngenkxaso yePPS kwi-RS232 serial okanye i-USB port.
Umamkeli weGPS oqhelekileyo akanakusebenza; Kusenokufuneka wenze uphendlo oluncinane ukuze ufumane echanekileyo.
3. Qinisekisa ukuba isixhobo siyayikhupha ngenene iPPS ukwenza oku, khangela izibuko nge gpsmon eluncedo.
4. Vula ifayile /etc/conf.d/gpsd kwaye uhlele umgca olandelayo.
Guqula
GPSD_OPTIONS=""ukuze kube njalo
GPSD_OPTIONS="-n"Olu tshintsho luyafuneka ukuze igpsd iqale ngokukhawuleza ukukhangela imithombo ye-SRNS ekuqaleni.
5. Qala okanye uqalise kwakhona igpsd.
(1:110)$ sudo /etc/init.d/gpsd start
(1:111)$ sudo /etc/init.d/gpsd restart
Ukusasaza nge-systemd, sebenzisa i-systemctl efanelekileyo umyalelo.
6. Jonga isiphumo se-console yomyalelo we-cgps.
Kufuneka uqinisekise ukuba idatha ifunyenwe ngokuchanekileyo kwiisathelayithi. Iconsole kufuneka ibe nento efana nomfanekiso.
Imveliso yomyalelo we-cgps console.
7. Lixesha lokuhlela ifayile /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
Ungeno oluphezulu lwe-NTP0 lubonisa umthombo wexesha jikelele okhoyo phantse kuzo zonke izixhobo ze-GPS. Ungeno olusezantsi lwe-NTP1 luchaza umthombo wePPS ochaneke ngakumbi.
8. Qala kwakhona i-ntpd.
(1:112)$ sudo /etc/init.d/ntpd restart
Ukusasaza nge-systemd, sebenzisa umyalelo we-systemctl.
$ sudo systemctl qala kwakhona ntp
Izinto ezisetyenzisiweyo
- UDavid L Mills IProtokholi yeXesha leNethiwekhi eMhlabeni nakwiSithuba,uHlelo lweSibini.
umthombo: www.habr.com