Me yasa tsayin GPS ko STRAVA ba daidai bane?

Tambaya ko tambaya mai maimaita ta taso game da daidaiton tsayi da bambance-bambancen tsayin GPS.

Duk da yake yana iya zama kamar maras muhimmanci, samun madaidaicin tsayi yana da ƙalubale, a cikin jirgin sama na kwance zaka iya sanya ma'aunin tef, igiya, sarkar geodesic, ko tara kewayen dabaran don auna nisa. a gefe guda kuma yana da wahala a sanya mitar 📐 a cikin jirgin a tsaye.

Tsawon GPS yana dogara ne akan misalin lissafin sifar duniya, yayin da tsayin daka akan taswirar yanayi ya dogara ne akan tsarin daidaitawa a tsaye da ke da alaƙa da duniya.

Don haka, waɗannan tsarin guda biyu ne daban-daban waɗanda dole ne su zo daidai a lokaci ɗaya.

Tsayin tsayi da digo a tsaye su ne sigogi waɗanda yawancin masu keke, masu hawan dutse, masu tuƙi, da masu hawan dutse za su so yin shawara da su bayan tafiya.

Umarnin don samun bayanin martaba a tsaye da kuma daidaitaccen bambance-bambancen tsayi an rubuta su da kyau a cikin littattafan GPS na waje (kamar littafin Garmin GPSMap kewayo), a juzu'i, wannan bayanin yana kusan babu ko ɓoyayyiya a cikin littattafan mai amfani da GPS da aka nufa. don masu keke (misali, jagororin kewayon Garmin Edge GPS).

Garmin Bayan Sabis na Siyarwa yana ba da duk shawarwari masu taimako, kamar TwoNav. Ga sauran masana'antun GPS ko apps (banda Strava) wannan babban gibi ne 🕳.

Yadda za a auna tsayi?

Dabaru da yawa:

• Yin amfani da sanannen ka'idar Thales a aikace,
• Daban-daban triangulation dabaru,
• Yin amfani da altimeter.
• Radar, Deal,
• Ma'aunin tauraron dan adam.

Barometric altimeter

Ya zama dole don ƙayyade ma'auni: altimeter yana fassara matsa lamba na yanayi zuwa wani tsayi. Tsayin 0 m yayi daidai da matsa lamba na 1013,25 mbar a matakin teku a zazzabi na 15 ° Celsius.

A aikace, waɗannan yanayi guda biyu ba su cika cika a matakin teku ba, alal misali, lokacin rubuta wannan labarin, matsa lamba a bakin tekun Normandy ya kasance 1035 mbar, kuma zafin jiki yana kusa da 6 °, wanda zai haifar da kuskure a wani tsayi. na kusan 500 m.

Altimeter na barometric yana ba da ingantaccen tsayi bayan daidaitawa idan yanayin matsa lamba / yanayin zafi ya daidaita.

Daidaitawa shine kiyaye ingantaccen tsayi don wuri, sa'an nan kuma altimeter ya daidaita wannan tsayin don amsa canje-canje a yanayin yanayi da zafin jiki.

Digowar zafin jiki 🌡 yana rage matsewar matsewa kuma tsayin daka yana ƙaruwa, haka ma idan zafin ya ƙaru.

Ƙimar tsayin da aka nuna za ta kasance mai kula da canje-canje a yanayin zafin jiki, mai amfani da altimeter, wanda ke riƙe ko sanye shi a wuyan hannu, ya kamata ya san tasirin canje-canjen zafin gida akan ƙimar da aka nuna (misali: agogon rufe / bude tare da hannun riga, dangi iska saboda sauri ko jinkirin motsi, tasirin zafin jiki, da dai sauransu).

Don sauƙaƙa tsayayyen yawan iska, shine yanayin kwanciyar hankali 🌥.

Lokacin amfani da shi daidai, altimeter na barometric ingantaccen kayan aiki ne don aikace-aikace iri-iri kamar su jirgin sama, yawo, hawan dutse ...

GPS mai tsayi

GPS yana ƙayyade tsayin wuri dangane da kyakkyawan yanayin da ke kwatanta duniya: "Ellipsoid". Tun da Duniya ba ta cika ba, wannan tsayin yana buƙatar canza shi don samun tsayin "geoid" 🌍.

Mai kallo wanda ya karanta tsayin alamar bincike ta amfani da GPS zai iya ganin karkatacciyar hanya ta dubun-dubatar mita, kodayake GPS ɗinsa yana aiki daidai a ƙarƙashin kyakkyawan yanayin karɓa. Wataƙila mai karɓar GPS yayi kuskure?

An bayyana wannan bambance-bambance ta hanyar daidaiton ƙirar ƙirar ellipsoid kuma, musamman, ƙirar geoid, wanda ke da rikitarwa saboda gaskiyar cewa saman duniya ba wuri ne mai kyau ba, ya ƙunshi abubuwan da ba su da kyau, yana ƙarƙashin gyare-gyaren ɗan adam kuma yana canzawa koyaushe. (Telluric da Human).

Waɗannan kurakuran za a haɗa su tare da kurakuran ma'auni da ke cikin GPS, kuma za su haifar da rashin daidaito da sauye-sauye na tsayin daka na GPS.

Tauraron tauraron dan adam geometries yana son kyakkyawan daidaito a kwance, wato, ƙarancin matsayi na tauraron dan adam akan sararin sama, yana hana ingantaccen tsayin daka. Tsarin girman madaidaicin madaidaicin shine sau 1,5 daidaitaccen madaidaicin.

Yawancin masana'antun kwakwalwan kwamfuta na GPS suna haɗa ƙirar lissafi cikin software. wanda ya kusanci tsarin geodetic na duniya kuma yana ba da tsayin da aka ƙayyade a cikin wannan ƙirar.

Wannan yana nufin cewa idan kuna tafiya a kan teku ba sabon abu ba ne don ganin mummunan ko matsayi mai kyau, saboda ƙirar geodetic na duniya ba ta da kyau, kuma ga wannan gazawar dole ne a ƙara kuskuren da ke cikin GPS. Haɗin waɗannan kurakuran na iya haifar da karkatar da tsayi sama da mita 50 a wasu wurare 😐.

An tsaftace samfuran geoid, musamman, altimetry da aka samu sakamakon matsayi na GNNS zai kasance mara kyau na shekaru da yawa.

Model Terrain Dijital "DTM"

DTM fayil ne na dijital wanda ya ƙunshi grid, kowane grid (filin farko na murabba'i) yana ba da ƙimar tsayi ga saman wannan grid. Wani ra'ayi na girman grid na yanzu na samfurin hawan duniya shine 30 m x 90 m. Sanin matsayi na matsayi a saman duniya (longitude, latitude), yana da sauƙi don samun tsayin wuri ta hanyar karantawa. fayil ɗin DTM (ko DTM, Samfurin Terrain na Dijital a Turanci).

Babban hasara na DEM shine amincin sa (ansu, ramuka) da daidaiton fayil; Misalai:

• Ana samun ASTER DEM tare da mataki (grid ko pixel) na 30 m, daidaito a kwance na 30 m da tsayin mita 20.
• Ana samun MNT SRTM a cikin tazarar mita 90 (grid ko pixel), kusan 16m altimita da daidaiton 60m na ​​planimetric.
• Samfurin Sonny DEM (Turai) yana samuwa a cikin 1°x1° increments, watau tare da girman tantanin halitta akan tsari na 25 x 30 m dangane da latitude. Dillali ya tattara mafi ingantattun hanyoyin bayanai, wannan DEM daidai ne kuma ana iya amfani da shi “a sauƙaƙe” don TwoNav da Garmin GPS ta taswirar OpenmtbMap kyauta.
• Ana samun IGN DEM 5m x 5m kyauta (daga Janairu 2021) a cikin matakan 1m x 1m ko 5m x 5m tare da ƙudurin tsaye 1m. An yi bayanin isa ga wannan DEM a cikin wannan jagorar.

Kar a rikitar da ƙuduri (ko daidaiton bayanan da ke cikin fayil ɗin) tare da ainihin daidaiton wannan bayanan. Ana iya samun karatu (ma'auni) daga kayan aikin da ba sa ba da damar kallon saman duniya zuwa mita mafi kusa.

IGN DEM, ana samun kyauta 🙏 daga Janairu 2021, wani faci ne na karatun (ma'auni) da aka samu da kayan aiki daban-daban. Wuraren da aka bincika don bincike na baya-bayan nan (misali haɗarin ambaliya) an duba su a ƙudurin 1 m, a wani wuri daidaito na iya yin nisa da wannan ƙimar. Duk da haka, a cikin fayil ɗin, an haɗa bayanan don cike filayen a cikin 5x5m ko 1x1m. IGN ta kaddamar da babban yakin neman zabe tare da burin cikar Faransanci gaba daya zuwa 2026, kuma a wannan rana, IGN DEM zai kasance daidai. kuma kyauta a tazara 1x1x1m....

DEM yana nuna haɓakar ƙasa: tsayin kayan aikin (ginai, gadoji, shinge, da dai sauransu) ba a la'akari da su ba. A cikin dajin, wannan shine tsayin ƙasa a gindin bishiyoyi, saman ruwa shine saman bakin tekun ga duk tafki mai girma fiye da hectare daya.

Duk maki a cikin tantanin halitta suna da tsayi iri ɗaya, don haka a gefen dutsen, saboda rashin tabbas na wurin fayil, wanda aka taƙaita tare da rashin tabbas na wurin, tsayin da aka cire zai iya zama daidai da tantanin halitta maƙwabta.

Daidaiton daidaitawar GPS a ƙarƙashin kyakkyawan yanayin liyafar yana cikin tsari na 4,5m a 90%. Ana ganin wannan aikin tare da mafi yawan masu karɓar GPS (GPS + Glonass + Galileo). Saboda haka, daidaito shine sau 90 daga cikin 100 tsakanin 0 da 5 m (sama mai tsabta, ban da masks, ban da canyons, da dai sauransu) na ainihin wurin. Yin amfani da DEM tare da tantanin halitta 1 x 1 m ba shi da amfani.saboda yuwuwar kasancewa akan madaidaicin grid zai yi wuya. Wannan zaɓin zai mamaye na'urar sarrafawa ba tare da ƙarin ƙimar gaske ba!

Don samun DEM wanda za'a iya amfani dashi a:

• BiyuNav GPS: CDEM na 5m (RGEALTI).

• Garmin GPS: Sonny Database

  Koyi yadda ake ƙirƙirar DEM naku don GPS Nav TwoNav. Za a iya fitar da matakan matakan ta amfani da software na Qgis.

Ƙayyade tsayi ta amfani da GPS

Magani ɗaya na iya zama don loda fayil ɗin DEM a cikin mahaɗan GPS ɗin ku, amma tsayin zai kasance abin dogaro ne kawai idan an rage girman grid kuma idan fayil ɗin ya isa daidai (a tsaye da a tsaye).

Don samun kyakkyawan ra'ayi game da ingancin DEM, ya isa ya duba, alal misali, taimako na tafkin ko gina hanyar da ta ƙetare tafkin kuma ku lura da hawan a cikin sashin 2D.

Hoto: software na LAND, kallon Lake Gerardmer a cikin haɓakar 3D x XNUMX tare da daidai DEM. Hasashen ramukan kan ƙasa yana nuna iyakar DEM na yanzu.

Hoto: Shirin LAND, kallon tafkin Gérardmer "BOG" a cikin 2D tare da daidaitaccen DTM.

Duk na'urorin GPS na zamani "kyakkyawan inganci" suna da kamfas da firikwensin barometric na dijital, saboda haka altimeter barometric; Yin amfani da wannan firikwensin yana ba ku damar samun ingantaccen tsayi muddin kun saita tsayi a wani wuri sananne (Shawarar Garmin).

Matsakaicin girman tsayin da GPS ke bayarwa tun zuwan GPS ya haifar da haɓaka algorithms haɗaɗɗen sararin samaniya waɗanda ke amfani da tsayin barometer da tsayin GPS don samar da ingantaccen matsayi na yanki. tsawo. Amintaccen bayani ne mai tsayi kuma zaɓin da aka fi so na masana'antun GPS, wanda aka inganta don aikin TwoNav na waje. da Garmin.

A Garmin, ana gabatar da kyautar GPS bisa ga bayanin mai amfani (waje, keke, hawan dutse, da dai sauransu), don haka yana da mahimmanci a koma ga littattafan mai amfani da sabis na tallace-tallace.

Mafi kyawun mafita shine saita GPS ɗin ku zuwa zaɓi:

• Altitude = Barometer + GPS, idan GPS ya ba da izini,
• Altitude = Barometer + DTM (MNT) idan GPS ya ba da izini.

A kowane hali, don GPS sanye take da barometer, da hannu saita barometer zuwa mafi ƙarancin tsayinsa a wurin farawa. A cikin tsaunuka ⛰ a kan dogon gudu, za a buƙaci a sake fasalin yanayin, musamman ma idan aka sami sauyin yanayi da yanayi.

Wasu Garmin GPS-ingantattun na'urorin kekuna ta atomatik suna sake saita tsayin barometric a sanannun wuraren tsaunuka, wanda shine mafita na musamman don hawan dutse. Duk da haka, mai amfani dole ne ya sanar, alal misali, kafin ya bar tsawo na wucewa da kasa na kwari; a hanyar dawowa, bambancin tsayi zai zama daidai 👍.

A cikin yanayin Barometer + (GPS ko DTM), masana'anta sun haɗa da algorithm na daidaitawa na barometer ta atomatik bisa ka'idar cewa hawan da barometer ya gani, GPS ko DEM dole ne ya kasance daidai: wannan ka'ida tana ba da sassauci ga mai amfani kuma ya dace da shi sosai. ayyukan waje.

Koyaya, mai amfani yakamata ya san iyakokin:

• GPS yana dogara ne akan geoid, don haka idan mai amfani yana motsawa ta hanyar wucin gadi (misali, don zubar da juji), gyare-gyaren za a gurbata.
• DEM yana nuna hanya a ƙasa, idan mai amfani ya karɓi wani muhimmin ɓangare na kayan aikin ɗan adam (viaduct, gada, gadoji masu tafiya, tunnels, da dai sauransu), gyare-gyaren za a daidaita su.

Sabili da haka, hanya mafi kyau don samun ingantaccen haɓaka haɓakawa shine kamar haka:

1️⃣ Daidaita firikwensin barometric a farkon. Idan ba tare da wannan saitin ba, za a canza tsayin daka (canza), bambancin matakin zai zama daidai idan ɗigon ruwa saboda yanayin yana da ƙananan (gajeren hanya a waje da duwatsu). Ga masu amfani da GPS na dangin Garmin, tsayin “gpx” Garmin da Strava ke amfani da shi don al'umma, don haka ya fi dacewa a shigar da madaidaicin bayanin martaba a cikin bayanan.

2️⃣ Domin rage rafkanwa (kuskure a tsayi da tsayi) saboda yanayin yanayi a cikin doguwar tafiya (> 1 hour) da kuma cikin tsaunuka:

• Mai da hankali kan zabi Barometer + GPS, wuraren waje tare da taimako na wucin gadi (yankunan juji, tsaunukan wucin gadi, da sauransu),
• Mai da hankali kan zabi Barometer + DTM (MNT)idan kun shigar da IGN DTM (5 x 5 m grid) ko Sonny DTM (Faransa ko Turai) a wajen hanyar da ke amfani da wani yanki mai mahimmanci na abubuwan more rayuwa ( gadoji masu tafiya, wucewar wucewa, da sauransu).

Haɓaka bambancin tsayi

Matsalolin tsayin da aka bayyana a cikin layin da suka gabata galibi suna bayyana kanta bayan lura da cewa bambancin tsayi tsakanin masu aikin biyu ya bambanta ko kuma ya bambanta dangane da ko ana karanta ta akan GPS ko a cikin aikace-aikacen kamar STRAVA (duba taimakon STRAVA) misali.

Da farko, kuna buƙatar daidaita GPS ɗin ku don samar da mafi girman tsayin da aka dogara.

Abu ne mai sauƙi don samun bambance-bambance a cikin matakan ta hanyar karanta taswirar, sau da yawa mai yin aiki yana iyakance don ƙayyade bambanci tsakanin maki na matsananciyar girma, ko da yake, don zama daidai, yana da muhimmanci a ƙidaya kyawawan layin kwane-kwane don samun jimlar. .

Babu layukan kwance a cikin fayil ɗin dijital, software na GPS, aikace-aikacen ƙirƙira waƙa, ko software na bincike an saita su don “tara matakai ko haɓaka haɓakawa”.

Yawancin lokaci "babu tarawa" ana iya daidaita su:

• a TwoNav zaɓuɓɓukan saitin sun zama gama gari ga duk GPS
• a Gamin ya kamata ku tuntuɓi littafin mai amfani da sabis ɗin bayan-tallace-tallace (kowane samfurin yana da nasa halayen bisa ga bayanin martaba na yau da kullun)
• aikace-aikacen OpenTraveller yana da zaɓi wanda ke ba da shawarar daidaita ƙimar hankali don tantance bambancin tsayi.

Kowa yana da nasa mafita 💡.

Shafukan yanar gizo ko software don nazarin kan layi yi ƙoƙari don maye gurbin tsayi daga fayilolin "gpx" tare da bayanan tsayin su.

Misali: STRAVA ya ƙirƙiri fayil ɗin altimetry na "an ƙasa" wanda aka ƙirƙira ta amfani da tsayin daka da aka samo daga waƙoƙin da aka samo daga. GPS da aka sani ga STRAVA kuma an sanye shi da firikwensin barometric, Maganin da aka ɗauka yana ɗauka cewa GPS ɗin STRAVA ce ta sani, don haka a halin yanzu ana samun ta ne daga kewayon GARMIN, kuma amincin fayil ɗin yana ɗauka cewa kowane mai amfani ya kula da sake saita tsayin da hannu. .

Dangane da abin da ya shafi aiki, matsalar tana tasowa musamman a lokacin tafiya rukuni, domin kowane mahalarta 🚵 zai iya lura cewa bambancin girman su ya bambanta da matakin sauran mahalarta, ya danganta da nau'in GPS, ko kuma mai amfani ne mai ban sha'awa wanda bai fahimta ba. dalilin da ya sa bambancin ke GPS tsawo, software na bincike ko STRAVA ya bambanta.

A cikin cikakkiyar tsaftar duniyar STRAVA, duk membobin ƙungiyar masu amfani da GPS GARMIN yakamata su ga tsayi iri ɗaya akan GPS ɗin su da kuma akan STRAVA ɗin su. Yana da ma'ana cewa ana iya bayyana bambancin kawai ta hanyar daidaita tsayi, duk da haka babu wani abu da ya tabbatar da bambancin tsayi da aka ruwaito daidai ne.

Yana da ma'ana cewa memba na wannan rukunin mai amfani wanda ke da GPS wanda ba a san shi da STRAVA ba ya kamata ya ga bambancin tsayi iri ɗaya akan STRAVA a matsayin mataimakansa, kodayake bambancin matakin da GPS ɗinsa ya nuna ya bambanta. Zai iya zargin kayan aikin sa, wanda duk da haka yana aiki daidai.

Har yanzu ana samun mafi kusanci ga ƙimar gaskiya na bambancin tsayi a cikin FRANCE ko BELGIUM lokacin karanta katin IGN., ƙaddamar da ingantaccen geoid zai motsa alamar ƙasa a hankali zuwa GNSS

GNSS: Wurin Kewayawa da Kewayawa Ta Amfani da Tsarin Tauraron Dan Adam: Ƙayyade matsayi da saurin batu a saman ko kusa da Duniya ta hanyar sarrafa siginar rediyo daga tauraron dan adam da yawa da aka samu a wancan lokacin.

Idan kana buƙatar dogara da software ko aikace-aikace don samun bambancin haɓakawa, dole ne ka daidaita wannan software don daidaita ƙimar matakin tarawa bisa layukan kwane-kwane na taswirar IGN na rukunin yanar gizon, wato 5 ko 10 m. Ƙaramin mataki zai juya zuwa digo duk ƙananan tsalle-tsalle ko sauye-sauye zuwa kumbura, kuma akasin haka, babban mataki zai shafe hawan ƙananan tsaunuka.

Bayan amfani da waɗannan shawarwari, gwajin marubucin ya nuna cewa ƙimar tsayin da aka samu ta amfani da GPS ko software na bincike sanye take da ingantacciyar DEM ta kasance cikin kewayon "daidai". zaton cewa taswirar IGN ma yana da nasa rashin tabbasidan aka kwatanta da kimanta da aka samu tare da katin IGN 1/25.

A gefe guda, ƙimar da STRAVA ta buga yawanci ana wuce gona da iri. Hanyar da STRAVA ke amfani da shi, dangane da "sake mayar da martani" daga masu amfani, a ka'idar yana ba ku damar yin hasashen haɗuwa da sauri zuwa ƙimar da ke kusa da gaskiya, wanda, dangane da adadin baƙi, yakamata ya riga ya faru a BikePark. ko waƙoƙin aiki sosai!

Don misalta wannan batu a zahiri, ga nazarin wata waƙa, da aka ɗauka ba tare da bata lokaci ba, akan titin tudu mai tsawon kilomita 20. An saita tsayin GPS na "barometric" kafin tashi, yana samar da "Barometric + GPS" tsayi, DTM shine ingantaccen DTM wanda aka sake tsarawa don zama daidai. Muna waje da yankin da STRAVA zai iya samun ingantaccen bayanin martaba.

Wannan wani kwatanci ne na waƙa inda bambanci tsakanin IGN da GPS shine mafi girma kuma bambanci tsakanin IGN da STRAVA shine mafi ƙanƙanta. Nisa tsakanin GPS da STRAVA shine 80m, kuma "IGN" na gaskiya yana tsakanin su.

Tsawoyi
tashi	Zuwan	Max	min	tsawo	Maɓalli / IGN
GPS (Barrier + GPS)	122	124	150	98	198	-30
Daidaita tsayi akan DTM	122	122	150	98	198	-30
FOOD	280	+ 51
IGN katunan	122	122	148	99	228,5	0