THE COMPARISON OF KOSAGA AND CORS-TR IN REAL TIME KINEMATIC POSITIONING (1)

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1 ACED UHMFD ULUSLARARASI HAKEMLİ MÜHENDİSLİK VE FEN BİLİMLERİ DERGİSİ THE COMPARISON OF KOSAGA AND CORS-TR IN REAL TIME KINEMATIC POSITIONING (1) GERÇEK ZAMANLI KİNEMATİK KONUM BELİRLEMEDE KOSAGA VE CORS-TR KARŞILAŞTIRMASI Cevat INAL 1, Sercan BULBUL, Omer YILDIRIM 1, Selcuk University, Geomatics Engineering Department, Konya / Turkey Gaziosmanpasa University, Geomatics Engineering Department, Tokat / Turkey Öz: Günümüzde GNSS (Global Navigation Satellite Systems) teknikleri kullanılarak nokta konumlarının gerçek zamanlı belirlenmesi mümkün olmaktadır. Nokta konumlarının gerçek zamanlı belirlenmesinde sabit bir noktaya dayalı GZK (Gerçek Zamanlı Kinematik) tekniği ya da sürekli gözlem yapan sabit GNSS istasyonlarına (CORS - Continuously Operating Reference Station) dayalı GZK teknikleri kullanılmaktadır. Ülkemizde de bazı belediyeler bölgesel amaçlı sürekli gözlem yapan GNSS istasyonları oluşturmuştur. Konya Büyükşehir Belediyesi de bu amaçla KOnya SAbit GNSS Ağını (KOSAGA) oluşturmuş bulunmaktadır. Mayıs 9 dan itibaren ülkemiz ve Kuzey Kıbrıs Türk Cumhuriyetini kapsayan 1 istasyondan oluşan TUSAGA-Aktif(CORS-TR) noktaları gerçek zamanlı konum belirlemede kullanılmaktadır. Bu çalışmada, Selçuk Üniversitesi kampüs alanında 1 noktada GZK tekniği, KOSAGA ve CORS-TR noktalarına dayalı olarak nokta konumları belirlenmiş ve elde edilen sonuçlar hızlı statik yöntemle elde edilen koordinatlarla karşılaştırılmıştır. Test alanında yapılan ölçülerin değerlendirilmesi sonucu hızlı statik yöntemle elde edilen koordinatlara en iyi yaklaşımı GZK yönteminin gösterdiği sonucuna varılmıştır. dx, dy koordinat farklarından yararlanarak hesaplanan ds lerin maksimum değerleri. ile 7. cm arasında, elipsoidal yüksekliklerdeki farklar ise 1 cm nin altındadır. Uygulanan yöntemlerin konum hataları karşılaştırıldığında, ortalama hataların ±1.7 cm ile ±.9 cm arasında değiştiği ve KOSAGA nında GZK ve CORS-TR sonuçlarına yakın sonuçlar verdiği görülmektedir. Anahtar Kelimeler: Ağ-RTK, CORS-TR, GZK GPS, KOSAGA Abstract: Nowadays, it is possible to determine point positions in real time by using GNSS (Global Navigation Satellite Systems) techniques. In real time determination of point positions, RTK(Real Time Kinematic) technique based on a fixed point or RTK techniques based on fixed GNSS stations (CORS Continuously Operating Reference Station) making continuously observation are being used. Also, in our country, some municipalities have established regional-purpose GNSS stations which make continuously observation. Konya Metropolitan Municipality has established KOnya SAbit GNSS Ağı (KOSAGA) for such purpose. From May 9, TUSAGA-Active (CORS-TR) points consisted of 1 stations including our country and Northern Cyprus Turkish Republic are under use in determining real time position.in this study, point positions have been determined at 1 points in the Selcuk University campus area as based on RTK technique, KOSAGA and CORS-TR points and the results obtained have been compared with the coordinates obtained through the rapid static method. As a result of evaluating the measurements taken in the test area, it has been concluded that the best approach to the coordinates obtained through the rapid static method has been exhibited by the RTK method. The maximum values of the ds calculated by making use of dx, dy coordinate differences are between. cm and 7. cm, and the differences in ellipsoidal heights are below 1 cm. When the position errors of the methods applied are compared, it can be seen that the root mean square errors are changing between ±1.7 cm and ±.9 cm and KOSAGA has also given results close to the results of RTK and CORS-TR. Key Words: Network-RTK, CORS-TR, RTK GPS, KOSAGA Doi: 1.17/UHMFD.119 (1) Corresponding Author: Ömer YILDIRIM, Selçuk University, Geomatics Engineering Department, Konya / Turkey omeryildirim@gmail.com Received: Accepted: Type ofarticle (Research and Practice) Conflict of Interest: None Ethics Committee: None 1

2 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) 1. INTRODUCTION Today, in geodetic surveys requiring high precision, static GPS surveying method from among relative position determining methods is being used and the measurements collected are evaluated in the office by means of appropriate GNSS software, hence, point positions are being determined (Kahveci and Yildiz, 1). However, in engineering applications, point positions have to be determined in real time while taking detail and during application. For this purpose, it has been developed the RTK (Real Time Kinematic) method which determines point positions in real time and at centimeter-level (Arslanoglu, ). However, in this method is required a reference station, position of which is known in high precision and one or more rover receiver located at a distance of at most 1- km to this station. Due to orbit and atmospheric errors, the accuracy of the method depends on the distance between the reference station and the rover receiver (Inal et al.,1a). In order to avoid such restrictions in the RTK method, the idea of setting up more than one fixed stations has been raised (Raquet, 199; Landau et al., ). CORS system was being started to be applied since the year-ends of 19s to make some contribution to geodetic surveys requiring high precision (Yildirim et al., 11). As a result of applying this idea and making use of the experiences obtained, the concept of fixed GNSS Networks (Network-RTK) has come out. The Network RTK method is being used in most of applications since, it is rapid, accurate and economic (Cina et al., 1). In Network- RTK system, dependence on a single reference station has been eliminated, moreover, also means to produce atmospheric modeling of a specific site by making use of data of many numbers of reference stations. And, as a result of such modeling, ionosphere and troposphere error which is one of the most significant error sources influencing the GNSS measurements are being taken to a minimum level for position determining practices. In this study, the real time coordinates obtained by using KOSAGA established by the Konya Metropolitan Municipality, CORS-TR produced under conduction of Istanbul Culture University and RTK technique, have been compared with the coordinates obtained by the rapid static method.. RAPID STATIC METHOD In position determining by GNSS, code observations or phase observations are being used. The rapid static method is one of the relative position determining methods applied by using phase observations and the point positions are being determined by evaluating in the office the collected measurements through appropriate GNSS software. In this method, one of the receivers is kept fixed on the reference point and while this makes observation continuously, the other receiver or receivers are set up at the other points for very short times and simultaneous observations are

3 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) made by this way (Kahveci and Yildiz, 1). Using fixed receiver CORS-TR stations which make observation continuously, makes it easy to determine the point positions. The users; can make static analysis by taking with their access passwords from the internet page of the General Directorate of Land Registry and Cadastre the fixed station data (seconds RINEX free-of-charge, 1 second RINEX against charge) regarding the land observation time. In this method, while the rover receiver is moved between the new points, position of which would be determined, it has not to be open. In this method, the measurement time period depends on the distance between the points and the satellite geometry, as the number of satellites increases, the measurement time period can be reduced in same length base (Table 1). In this method, the base measurement accuracy is mm+. ppm at horizontal, and mm+.ppm at vertical (Anonymous-1, 1; Anonymous-, 1). Table 1. The Relationship Number Of Satellites And Measurement Time Period (Kahveci and Yildiz, 1) Number of Satellites Measurement Time Period (minute) > 1- and above -1. RTK GPS Position determining by RTK is a position determining technique which is implemented as based on the phase observations recorded by the rover receivers from the satellites (GPS/GLONASS) and raw measurements or correction data (position, pseudorange, atmosphere, etc.) sent in real time to the rover receiver simultaneously from a reference station and the calculations which are made in the rover receiver (Kahveci, 9). In the RTK technique, dual-frequency GPS receivers are used in both, the reference station and the rover station. Furthermore, in this method, some additional hardware are required as different from the hardware used in the static and kinematic GNSS measurement methods; a radio transmitter transmitting the calculated carrier wave phase measuring corrections is used in the fixed station and a radio receiver which receives these sent corrections is used in the rover receiver (Mekik, 1). In the RTK applications, the corrections calculated in the reference station are being sent to the rover receiver. The correction messages which are sent should be in line with a specific format. Each receiver firm has generated its own special format for real time applications. However, in such a case, the data of different formats can t be used by different receivers. In order to avoid this problem, the Radio Technical Commission for Maritime Services, Special Committee-1

4 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) has published a standard format in order to transmit the correction data between the reference receiver and the rover receiver and this format has been named as RTCM SC-1 (Hofmann et al., 1997). The RTCM SC-1 format is almost the same of the GPS navigation message format. Experiences have shown that the RTCM SC-1 data format and message structure are reliable in general (Arslanoğlu and Mekik, ). In the RTK method, the more numbers of satellites are observed by the reference and rover receivers, according number of satellites which are observed, the initial integer ambiguity is resolved more rapid and the position accuracies are increased (Sickle,1). For this purpose, in addition to the GPS signals, it can be benefit from the other systems which use GLONASS signals. The GPS/GLONASS dual systems are more advantageous in regions which have limited sky opening such as in determining open basin mines, city canyons, river valleys and forest boundaries (Arslanoğlu and Mekik, ). In the RTK applications, the correction data calculated in a reference station are sent to the rover receiver. In order to avoid systematic errors (atmospheric effects, orbit error etc.), the distance between the reference station and the rover receiver should not be longer than 1- km. The accuracy obtained in centimeter-level by the RTK technique is being considered sufficient for many numbers of surveying applications (Pektas, 1).. CORS TR In order to overcome the restriction of RTK made with a single reference receiver, the world of science and technology continuously researched it and as a result of such researches, the Network- RTK method has been developed. Because, the Network-RTK system gives rapid, accurate, economic and reliable results, it is being preferred todays. However, when the users go out of the coverage area of the GSM, they can t make any measurements anymore (Cina et al., 1). The Network RTK system consists of three main parts as reference stations in intervals of -1 km, the central processing unit and the users (Figure 1). The reference stations connected to the central processing unit by broadband links. The central processing unit receives firstly the raw data and it calculates the real-time corrections or correction elements after evaluating these. Through wireless connection the users can access to such corrections in real time (Meng et al., ).

5 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) Figure 1. Schematic of the Fundamentals of Network-RTK GNSS (Lecia Geosystems, ) In the Network-RTK system, dependence on a single reference station has been eliminated and furthermore, means has been ensured to make atmospheric modeling of a specific site by making use of the data of many numbers of reference stations, the power of the GNSS observation techniques has been combined with the advantages of the network structure. As a conclusion, the Network-RTK is a real time position determining technique in centimeterlevel accuracy as based on phase observations in base lengths (-1 km) longer than those in the Classic RTK technique (Kahveci, 9). The rover receiver in the Network RTK system is connected to the server through one or two different ways (such as, radio modem, GSM(Global System for Mobile Communications) or internet). As soon as it receives the real time kinematic data, it calculates its position according to a appropriate algorithm. Different methods are being used also in transferring the network data to the rover receivers. These methods change depending on whether the corrections are made in the reference station or rover receiver, the scope of the data to be sent, the data transmitting format and protocol (radio, GPRS, etc.) (Pektas, 1). The Network-RTK has its superiorities with respect to the Classic RTK. By Network-RTK, the point coordinates are being determined in a single meaning and homogeneous coordinate system, high-quality results are being obtained by making use of an atmospheric model generated for the whole network and the corrections required for the measuring point can be calculated by interpolation (Kahveci, 9). The type of the Network-RTK which is applied today most widely is the global fixed GNSS Networks. The CORS-TR network consisted of

6 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) 1 points have been established in our country for such purpose. In the CORS-TR Project, active CORS approach has been adopted. Here, the CORS stations including the whole country are connected to a control center and the positions of the stations and the atmospheric corrections are being calculated continuously. Thus by this way, the atmosphere and position corrections can be modeled all over the country. As a result of these, the GNSS measuring times requiring hours are reduced to minutes and even down to seconds; and, the base lengths are increased by 1 times approximately (Eren and Uzel, ).. KOSAGA In order to make use of the satellite systems effectively and economically, as in developed countries, in our country local networks consisted of real time fixed reference stations have been established by Municipalities/Authorities. The -point ISKI (Istanbul Water and Sewerage Administration) UKBS (Position Determining System From Satellites) established in by ISKI and -point KOSAGA(Konya Fixed GNSS Network) established in 1 by the Konya Metropolitan Municipality can be shown as examples for these(anonymous-,1). Fixed GNSS station (KONB) to be used in RTK measurements in Konya has been established in 9 on the roof of municipality building by the Konya Metropolitan Municipality. However, the service area of the municipality which renders service for an area of approximately km as per the Metropolitan Municipality law dated /7/ and numbered 1, has been increased to km by the law dated 1/11/1 and numbered. In the measurements made by taking as reference the KONB station problems have been encountered with in generating position data because, the distance was increased due to the new extended boundaries. In order to solve the problem, new GNSS stations have been established by the Konya Metropolitan Municipality in Ilgın, Beyşehir, Oğuzeli and Hotamış districts, thus, a -point network has been established (Figure ). Under this network structure, as Konya is the center, RTK measurements can be done in an area with a radius of approximately 1 km. In KOSAGA, Trimble Net R9-Ti1 receiver and Zephyr GNSS Geodetic II antennas have been used. The system can generate position data by means of various measuring techniques such as static, rapid static, RTK, DGPS based on code and phase measurements (Ustun, 1). In terms of network correction, KOSAGA transmits only VRS (Virtual Referance Stations) correction (NET RTCM,NET CMR+). It doesn t transmit the FKP(Flachen Korrectur Parameter) and MAC (Master Auxliary Concept) correction models nearby VRS. Nevertheless, all the stations can transmit RTK correction (KONYA SGNL, KONYA RTCM) independently to work in the classic RTK system.

7 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) Figure. KOSAGA and Base Lengths. APPLICATION.1. Measurements Performed in Test Area and Evaluation The road located in front of the Vocational School Of Technical Sciences and Faculty of Architecture within the Konya Selcuk University Alaeddin Keykubat Campus area has been used as the test area (Figure). Figure. Test Area GPS measurement has been made with Javad Triumph-1 GNSS receiver at 1 points marked on the road, by means of rapid static method by taking measuring time 1 minutes, recording 7

8 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) interval seconds and elevation angle of 1 o and this has been evaluated through LGO 7. (Leica Geo Office 7.) software and coordinates of the points have been calculated at ITRF9/. based on CORS-TR network. Measurement accuracy of GNSS receiver used in the application in static survey and rapid static method is; s being the distance to the reference point; at horizontal:. cm +.1 ppm. s, at vertical:. cm +. ppm. s, and in RTK measurements at horizontal : 1cm +1 ppm. s, at vertical :1. cm + 1 ppm. s (Anonymous-, 1). In the comparison, the accuracies of the other methods have been investigated by taking as basis the coordinates obtained by rapid static method. In the 1 points in the test area, VRS correction technique has been used with CORS-TR based on the experiences in the paper carried out previously( İnal et al., 1b), and in the measurements taken with KOSAGA;NET_RTCM, NET_CMR+, KONYA_RTCM and KONYA_SNGL correction techniques have been used. In the RTK measurements, point coordinates have been determined by taking constant the L9-G numbered TUTGA SLCK(.) point (y=.77(east), x= (up), h=1.7) located within the campus area of Selcuk University. The distance of the TUTGA SLCK point to the test points is approximately 1km, and the KONB point nearest to the test area from the KOSAGA points is approximately 17 km. In the CORS-TR, KOSAGA and RTK measurements, epoch measurements have been made with 1 second record interval. In all measurements taken, the number of GPS satellites and the number of GLONASS satellites change between and 9, and 7, respectively. By taking as basis the coordinates calculated by rapid static method; the coordinate differences and the ellipsoidal height differences have been calculated by means of the following equalities: dx=x HS -X dy=y HS -Y (1) dh=h HS -h In the equalities; X HS, Y HS, h HS represent the coordinates and ellipsoidal heights obtained by the rapid static method and X,Y, h represent the coordinates and ellipsoidal heights determined by means of other methods. And, by making use of the coordinate and ellipsoidal height differences in equation (1); the root means square errors in the directions of x, y and h have been calculated by means of the following equations (Table ): ()

9 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) Table. Coordinate Differences and Root Mean Square Errors Calculated Method Taken as Reference HS Method Compared RTK CORS-TR NET RTCM NET CMR+ KONYA SGNL KONYA RTCM Difference Statistics dy(cm) dx(cm) dh(cm) max min avrg rmse max... min avrg rmse max.1.7. min avrg rmse max min avrg rmse max min avrg rmse max min avrg rmse.1..7 By using the calculated dx, dy coordinate differences, the change in each measuring point has been calculated by means of the following equation (Table ). () 9

10 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) Table. Calculated Coordinate Changes Compared Method ds(cm) max. RTK min.1 avrg 1.9 max.1 CORS-TR min. avrg.9 max.9 NET RTCM min.1 avrg.9 max.9 NET CMR+ min.1 avrg. max.9 KONYA SGNL min 1. avrg.1 max 7. KONYA RTCM min. avrg. The figures of ds values calculated according to equation () for each measuring point can be seen in figure -9, and the figures of dh values calculated according to equation 1 can be seen in figure 1-1. ds (cm) Figure. Comparison of Rapid Static RTK 1

11 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) ds (cm) ds (cm) 7 1 Figure. Comparison of Rapid Static-CORS-TR Figure. Comparison of Rapid Static- KOSAGA (Correction Technique: NET_RTCM) ds (cm) Figure 7. Comparison of Rapid Static- KOSAGA (Correction Technique: NET_CMR+) 11

12 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) ds (cm) Figure. Comparison of Rapid Static - KOSAGA (Correction Technique: KONYA_SGNL) ds (cm) Figure 9. Comparison of Rapid Static and KOSAGA (Correction Technique: KONYA_ RTCM ) The figures of ellipsoidal height differences (dh) are as given below. 1

13 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) dh (cm) Figure 1. Comparison of Ellipsoidal Heights of Rapid Static and RTK dh (cm) Figure 11. Comparison of Ellipsoidal Heights of Rapid Static and CORS-TR dh (cm) Figure 1. Comparison of Ellipsoidal Heights of Rapid Static and KOSAGA (Correction Technique: NET_RTCM) 1

14 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) dh (cm) Figure 1. Comparison of Ellipsoidal Heights of Rapid Static and KOSAGA (Correction Technique: NET_CMR+) dh (cm) Figure 1. Comparison of Ellipsoidal Heights of Rapid Static and KOSAGA (Correction Technique: KONYA_SGNL) dh (cm) Figure 1. Comparison of Ellipsoidal Heights Of Rapid Static And KOSAGA (Correction Technique: KONYA_RTCM )

15 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) Positioning accuracy for each method used in the comparison has been calculated by means of the following equation by using the values of m x, m y in Table 1(figure 1); () Table.Positionning Accuracies Of The Methods Used Method m p (cm) RTK ± 1.7 CORS-TR ±. NET RTCM ±.7 NET CMR+ ±.1 KONYA SGNL ±.7 KONYA RTCM ±.9 7 m y m x m p m h rmse(cm) 1 RTK CORS NET RTCM NET CMR+ KONYA SGNL KONYA RTCM Method Figure 1. Values of m y, m x, m p and m h 7. CONCLUSION AND RECOMMENDATIONS In real time positioning technique, one of the receivers is set up on the reference point, position of which is already known, whereas, the rover receiver is fixed at the points, positions of which would be determined, thus, the coordinates of the new points are determined. In such a case, it is recommended that the distance between the reference receiver and the rover receiver doesn t exceed 1 km. In order to eliminate such disadvantage, GNSS stations making continuously observation have been established. By this way, the need for a reference receiver has been eliminated and the position of a new point could be determined in real time by means of a single receiver. In this study, in 1 points in the campus area of Selcuk University point positions have been 1

16 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) determined based on RTK technique, KOSAGA and CORS-TR and the results obtained have been compared with the coordinates obtained by means of rapid static technique. As result of evaluating the measurements taken in the test area, when figure -1 is examined, it has been concluded that the best approach to the coordinates obtained by rapid static method has been shown by the RTK method. The maximum values of the ds calculated by making use of dx, dy coordinate differences are between. cm and 7. cm, and the differences in ellipsoidal heights are below 1 cm. When the m p position root mean square errors in Table. are compared, it can be seen that the root mean square errors are changing between ± 1.7 cm and ±.9 cm and that the best result is given by the RTK method. When the results obtained are evaluated together, it is being considered that KOSAGA could be used satisfactorily in fields such as cadastral studies, zoning plan applications, the present time map, etc. as it is in RTK and CORS-TR.. REFERENCES ANONYMOUS-1,(1). Lecia Viva GNS- SGS1 receiver User Manual, (Access Date: 1.1.1) ANONYMOUS-, (1). JAVAD GROUP OF COMPANIES, com/productsurvey/articles/ id17-javad_ GNSS.html,(Access Date: 1.1.1) ANONYMOUS-, (1), Istanbul Metropolitan Municipality, ukbs.iski.gov.tr, Access Date :..1 ANONYMOUS-, (1). JAVAD GROUP OF COMPANIES, javadgnss/sheets/triumph-1_datasheet. pdf, (Access Date:..1) ARSLANOĞLU, M.,(). Investigating the Usability of the Real Time Kinematic GPS in Urban Information Systems, Master of Science Thesis, ZKÜ FBE, Zonguldak ARSLANOĞLU, M., & MEKİK, Ç., (). Accuracy Analysis of Real Time Kinematic GPS Positions and a Sample Application, 9.Turkish Map and Scientific Technical Congress,Ankara, 9- CINA, A., DABOVE, P., MANZİNO, A.M., PİRAS, M., (1). Augmented Positioning with CORSs Network Services Using GNSS Mass-market Receivers. In: 1 IEEE/ION Position, Satellite Positioning - Methods, Models and Applications Location and Navigation Symposium (PLANS), Monterey (CA-U.S.A.), May -, pp. 9- CINA, A., DABOVE, P., MANZİNOA. M., PİRAS, M., (1). Network Real Time Kinematic (NRTK) Positioning Description, Architectures and Performances, dx.doi. org/1.77/9, Chapter, pp: - 1

17 Eylül / Ekim / Kasım / Aralık Sonbahar Kış Dönemi Sayı: Yıl:1 September / October / November / December Issue Autumn Winter Period: Year: 1 ID:9 K:1 (ISO 91- Belge No / Document No: 179 & ISO 11- Belge No / Document No: 1) (1/- 1-GE-177) EREN, K., & UZEL, T., (). Establishing of the National CORS System and Datum Transformation Project, İstanbul HOFMANN - WELLENHOF, B., LICTE- NEGGER, H., COLLINS, J., (1997). GPS TheoryandPractice, New York KAHVECI, M., (9). Kinematic GNSS and RTK CORS Networks, Zerpa Tourism Publication Ltd.Co., Ankara KAHVECI, M., & YILDIZ, F.,(1). Position Determining Systems With GPS/GNSS Satellites, Theory and Practice, Nobel Academic Publication,.Edition, Ankara, p. LANDAU, H., VOLLATH, U., CHEN, X., (). Virtual Reference Station Systems, Journal of Global PositioningSystem, Vol. 1, No., Canada, 17-1 LEICA GEO SYSTEMS, (). GPS Spider: New Conceptsand Architecture, trainingmaterial MEKIK, C., (1). Time Kinematic GPS, Seminar study, ZKÜ, Zonguldak, p.11 MENG, X., DODSON, A., MOORE, T., HILL, C.; ROBERTS G.W., EULER, H.J., ALVES, P.,(). QualityMeasures of the Nottingham Network RTK GPS Testbed:Preliminary Research, presented at International Symposium ongps/gnss, Hong Kong INAL, C., BULBUL, S., YILDIRIM, O., (1a). Repeatability of Network RTK Measurements, Afyon Kocatepe University Science and Engineering Sciences Journal, p.1-7, Afyonkocatepe INAL, C., GUNDUZ, A.M., BULBUL, S., (1b). Comparison of Classical RTK and Network RTK Methods, S.U. Eng.Science and Techn. Journal, volume, issue, Konya, p.19-9 PEKTAS, F., (1). Kinematic Positioning Based On Real Time National and Local Fixed GNSS Networks, Master of Science Thesis, YTU FBE, İstanbul RAQUET, J., (199). Development of a MethodforKinematic GPS Carrier-PhaseAmbiguityResolution Using Multiple Reference Receivers. PhDThesis, UCGE 11, University of Calgary SICKLE, J.V., (1). GPS for Land Surveyers, Second Editation, Taylor&Francis, New York, USA USTUN, A., (1). KOSAGA Project Technical Control Report, Konya YILDIRIM, O., SALGIN, O., BAKICI, S., (11). The Turkish CORS Network (TUSAGA- Aktif), FIG Working Week 11, Bridging the Gap between Cultures, 1-1 May 11, Marrakech, Morocco 17