Usability of Precise Point Positioning PPP Technique In Hydrographic Surveying

Abstract

In this study, a series of studies were conducted in order to test the performance of the Precise Point Positioning PPP Technique in marine applications dynamic environments . 2-hour measurements were carried out in Haliç, İstanbul in this context. A dual frequency geodetic GPS antenna, located on the vessel, was connected to a dual frequency geodetic grade GPS receiver Ashtech Z-Xtreme and an OEM single frequency GPS receiver Ashtech AC12 via an antenna splitter. Another geodetic GPS receiver was set up on a reference point on the shore for relative positioning of the antenna. The coordinates of the antenna were calculated in cm accuracy level using the data gathered by the geodetic GPS receivers on the vessel and at the shore. Coordinates of each epoch were calculated with the PPP technique by sending the data to the on-line GPS processing service, CSRS-PPP, gathered by both the geodetic and OEM receivers and the PPP-derived coordinates obtained from the service were compared with the ones calculated by relative positioning. According to the assessments, results obtained from single frequency low-cost OEM receivers converges the results of the relative positioning results within 1-2 meters of positioning accuracy. The results from dual frequency receivers meet at decimeter-level positioning accuracy level the service used code and carrier phase data when dual frequency data is available. The obtained results show that the proposed method is able to meet the accuracy requirements in several hydrographic surveying applications.

Keywords

• Precise Point Positioning PPP , GPS, Hydrographic Surveying.

Hassas Nokta Konumlama Tekniğinin Hidrografik Ölçmelerde Kullanılabilirliği

Abstract

Bu çalışmada, hassas nokta konumlama Precise Point PositioningPPP yönteminin dinamik ortamlardaki performansını test etmek üzere bir dizi çalışma gerçekleştirilmiştir. Bu kapsamda İstanbul Haliç’te bir tekneyle yaklaşık 2 saat süren bir uygulama yapılmıştır. Tekneye konulan jeodezik çift frekanslı GPS antenine bir anten splitter yardımıyla çift frekanslı jeodezik Ashtech Z-Xtreme ve tek frekanslı OEM tipi tek frekanslı GPS alıcısı Ashtech AC12 bağlanmıştır. Antenin rölatif yöntemle koordinatını belirlemek için kıyıda tesis edilen koordinatı bilinen bir noktaya da bir başka jeodezik GPS alıcısı kurulmuş ve veri toplanmıştır. Kıyıdaki ve teknedeki jeodezik GPS alıcıları ile toplanan verilerden yararlanarak antenin konumu cm mertebesindeki doğrulukla belirlenmiştir. Teknede hem jeodezik hem de OEM alıcıları ile toplanan veriler Kanada CSRSPPP servisine gönderilerek her bir ölçme anının epoch PPP yöntemi ile koordinatı belirlenmiş ve bu koordinatlar rölatif yöntemden elde edilenlerle karşılaştırılmıştır. Değerlendirme sonucunda, tek frekanslı düşük maliyetli OEM tipi alıcıdan elde edilen sonuçların, rölatif yönteme 1-2 metre doğrulukla yakınsadığı görülmüştür. Çalışmada kullanılan çift frekanslı alıcı ile toplanan veriler değerlendirilirken yazılım, hem faz hem de kod ölçülerini kullanmakta olduğundan daha yüksek mertebede doğruluklara 1-2 dm ulaşılmıştır. Elde edilen bu sonuçlar söz konusu yöntemin birçok hidrografik ölçme uygulamasında gereksinim duyulan doğrulukları karşılayabilecek düzeyde olduğunu göstermiştir.

Keywords

• Hassas Nokta Konumlama PPP , GPS, Hidrografik Ölçmeler.

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