Erinevate Eesti VRS võrkude ja üksikute GNSS baasjaamade täpsushinnang
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Kuupäev
2014
Kättesaadav alates
Autorid
Svežova, Margarita
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Käesoleva bakalaureusetöö eesmärgiks oli Eestis töötavate VRS võrkude ja erinevate GNSS baasjaamade RTK täpsusele hinnangu andmine. Eesmärgi saavutamiseks mõõdeti X, Y koordinaadid, ellipsoidi kõrgust ja initsialiseerimisaega kuuel tihendusvõrgupunktil, millest kolm asusid Tartumaal ja kolm Ida-Virumaal. Välitöödel kasutati GNSS vastuvõtjat Trimble R4. Samuti olid kasutusel Trimble VRS Now, HadNet (Topcon) ja kolm üksikut baasjaama: Tõravere, Toila ja EMU. Välitööde käigus igal tihendusvõrgupunktil mõõdeti initsialiseerimisaega (millal vastuvõtja saavutas Fixed lahenduse) ning peale initsialiseerimist mõõdeti koheselt X, Y koordinaadid ja ellipsoidi kõrgust. Mõõtmine lõpetati ning alustati uut initsialiseerimist ja nii tegutseti kolm korda igal mõõdetaval tihendusvõrgupunktil. Hiljem võrreldi mõõtmistulemused Maa-ameti koordinaatide ja ellipsoidi kõrgustega. Samuti selgitati välja baasjaama kauguse mõju initsialiseerimisajale. Kuue tihendusvõrgupunkti mõõtmiste ajal kiireim initsialiseerimine toimus Trimble VRS võrgus keskmiselt 16 sekundit. Hea tulemus oli ka Topcon VRS võrgus, keskmiselt kulus initsialiseerimiseks 39 sekundit. Tartumaa punktidel toimus kõige kehvem initsialiseerimine Toila baasjaamas, kuna initsialiseerimisajaks kujunes üle 2 minuti ning vastuvõtja saavutas ainult Float lahenduse. Põhjuseks oli Toila baasjaama paiknemine 125 kilomeetri kaugusel tihendusvõrgupunktidest. Ida-Virumaal toimus kõige kehvem initsialiseerimine Tõravere ja EMU baasjaamades. Sarnaselt Toila baasjaamaga Tartumaal, kulus initsialiseerimiseks aega üle 2 minuti ning nende kaugus Ida-Virumaal asuvatest punktides oli 100 kuni 125 km. Kahe VRS võrgu keskmiseks mõõtmistäpsuseks kujunes ±1.8 cm ning kolme üksiku baasjaama keskmiseks mõõtmistäpsuseks oli ±4.8 cm. Üksikute baasjaamade täpsus erines VRS võrkude täpsusest ligikaudu 3 cm võrra. Niisugune erinevus võis olla tingitud sellest, et oli baasjaamu, mis asusid ligikaudu 125 km kaugusel mõõdetavatest objektidest. Uurimistöö põhjal oli näha, et baasjaama kaugus liikuvjaamast mõjutas algtundamatulahendamise kiirust ning vastuvõtja staatused, kas Fixed või Float, mõjutasid GNSS vastuvõtja mõõtmistäpsust. Samas VRS võrkude GNSS püsijaamade kaugus ei mõjutanud initsialiseerimiskiirust, kuna VRS võrgus olevale GNSS vastuvõtjale oli loodud kiiresti virtuaalne referentstugijaam 20-30 m kaugusele. Samuti Trimble VRS Now võrk funktsioneeris paremini Tartumaal ning HadNet Ida-Virumaal.
The aim of this BA Thesis was to evaluate VRS networks, base stations, and various GNSS RTK accuracy. To achieve this goal, measurements were executed for X, Y coordinates, ellipsoid height and initialization time in six densification network points, three of those were located in Tartumaa and three in Ida-Virumaa. Trimble R4 GNSS receiver was used during the fieldwork. During the measurements Trimble VRS Now, HadNet (Topcon) and three single base station: Tõravere, Toila, and EMU were used. In the course of the fieldwork initialization time (when the GNSS receiver reaches Fixed solution) measurements were taken in every densification network point, and X, Y coordinates and ellipsoid height were measured immediately after initialization. After interruption of the measurement, new one initialization was started and this procedure was repeated three times in every measurable densification network point. Later, measurement results were compared with the Land Board coordinates and ellipsoid heights. The influence of the distance from the single base station on the initialization time was also explained. During the measurement in six densification network points, the fastest initialization was in the Trimble VRS network, an average of 16 seconds. A good result was also obtained for Topcon VRS network, wherein initialization took an average of 39 seconds. In the course of Tartumaa densification network points measurement, the worst initialization was in Toila base station, this took more than two minutes, and only Float solution was achieved. The reason was in Toila base station, because it is located in 125 kilometers away from the densification network points. During the measurement in Ida-Virumaa densification network points, the worst initialization was in Tõravere and EMU base stations. It also took more than two minutes, and the distance to the densification network points was 100 to 125 km. The average accuracy of the two VRS networks was ± 1.84 cm and the average accuracy of three single base station was ± 4.83 cm. The accuracy of individual base stations differed from the accuracy of the VRS networks by approximately 3 cm. This difference may be due to the fact that there were base stations, which are located in about 125 km from the measurable objects. In the research work it could be seen that the distance station from the base to the mobile station affects initialization speed of the receiver as well as on solutions, Fixed or Float, which affect measurement accuracy of the GNSS receiver. At the same time, the distance from the GNSS reference station of the VRS network does not affect the initialization speed, because the VRS network can quickly establish a virtual reference station located in 20-30 meters away from the the GNSS receiver. Looking at the measurement results, it is seen that the Trimble VRS Now network was functioning better in Tartumaa, whereas operation of HadNet was better in Ida-Virumaa.
The aim of this BA Thesis was to evaluate VRS networks, base stations, and various GNSS RTK accuracy. To achieve this goal, measurements were executed for X, Y coordinates, ellipsoid height and initialization time in six densification network points, three of those were located in Tartumaa and three in Ida-Virumaa. Trimble R4 GNSS receiver was used during the fieldwork. During the measurements Trimble VRS Now, HadNet (Topcon) and three single base station: Tõravere, Toila, and EMU were used. In the course of the fieldwork initialization time (when the GNSS receiver reaches Fixed solution) measurements were taken in every densification network point, and X, Y coordinates and ellipsoid height were measured immediately after initialization. After interruption of the measurement, new one initialization was started and this procedure was repeated three times in every measurable densification network point. Later, measurement results were compared with the Land Board coordinates and ellipsoid heights. The influence of the distance from the single base station on the initialization time was also explained. During the measurement in six densification network points, the fastest initialization was in the Trimble VRS network, an average of 16 seconds. A good result was also obtained for Topcon VRS network, wherein initialization took an average of 39 seconds. In the course of Tartumaa densification network points measurement, the worst initialization was in Toila base station, this took more than two minutes, and only Float solution was achieved. The reason was in Toila base station, because it is located in 125 kilometers away from the densification network points. During the measurement in Ida-Virumaa densification network points, the worst initialization was in Tõravere and EMU base stations. It also took more than two minutes, and the distance to the densification network points was 100 to 125 km. The average accuracy of the two VRS networks was ± 1.84 cm and the average accuracy of three single base station was ± 4.83 cm. The accuracy of individual base stations differed from the accuracy of the VRS networks by approximately 3 cm. This difference may be due to the fact that there were base stations, which are located in about 125 km from the measurable objects. In the research work it could be seen that the distance station from the base to the mobile station affects initialization speed of the receiver as well as on solutions, Fixed or Float, which affect measurement accuracy of the GNSS receiver. At the same time, the distance from the GNSS reference station of the VRS network does not affect the initialization speed, because the VRS network can quickly establish a virtual reference station located in 20-30 meters away from the the GNSS receiver. Looking at the measurement results, it is seen that the Trimble VRS Now network was functioning better in Tartumaa, whereas operation of HadNet was better in Ida-Virumaa.
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