Investigation of reliability of the variance covariance matrices obtained from GIPSY-OASIS II v6.4 software for precise point positioning

Year 2019, Volume: 6 Issue: 2, 75 - 86, 01.11.2019

Bahattin Erdoğan Orhan Kayacık Ali Hasan Doğan

https://doi.org/10.9733/JGG.2019R0007.T

Abstract

In recent years Precise
Point Positioning (PPP) technique is one of the most important subjects in
Geomatic Engineering. PPP technique needs only one Global Navigation Satellite
Systems (GNSS) receiver thus users have preferred it instead of traditional
relative positioning technique for several applications. Nowadays, scientific
software generally has been used for PPP solutions and the Variance covariance
(VCV) matrices estimated from software are very optimistic. The formal errors
estimated from VCV matrices have major effects on statistical interpretation.
VCV matrices derived from GNSS processing software play important role for
deformation analysis and scientists sometimes need to scale VCV matrices. In
this study, 10 continuously operating International GNSS Service (IGS)
reference stations have been considered for 11 days dated 2014. All points have
been analyzed by GIPSY-OASIS II v6.4 scientific software. It is aimed to
estimate scale factor for the PPP results obtained from GIPSY-OASIS II v6.4
with considering different session durations as 2, 4, 6, 8, 12 and 24 hours.
According to the results, the values of the scale factors raise depending on
the raises in respect of session duration.

Keywords

GIPSY-OASIS II v6.4, Precise point positioning, Variance covariance matrix, Scale factor, Reliability

Hassas mutlak nokta konumlamada GIPSY-OASIS II v6.4 yazılımı ile elde edilen varyans kovaryans matrisinin güvenirliğinin araştırılması

Abstract

Hassas Mutlak Konum
Belirleme (Precise Point Positioning - PPP) tekniği, harita/geomatik
mühendisliği uygulamalarında son yıllarda öne çıkan önemli konulardan
birisidir. PPP tekniğinde konumu belirlenecek noktada yalnızca bir tek Küresel
Navigasyon Uydu Sistemleri (Global Navigation Satellite Systems (GNSS))
alıcısının kullanılması yeterlidir. Bu nedenle kullanıcılar bu tekniği birçok
uygulamada geleneksel bağıl konumlama yöntemine göre tercih etmektedirler. PPP
tekniği ile yapılan çalışmalarda veri değerlendirme ve analiz aşamalarında
günümüzde genellikle bilimsel yazılımlar kullanılmaktadır. Bu yazılımlardan
elde edilen Varyans kovaryans (VKV) matrisleri ise çok iyimser sonuçlar
vermektedir. VKV matrislerinden hesaplanan değerler istatistiksel
yorumlamalarda önemli etkiye sahip unsurlardır. GNSS veri değerlendirmesi
sonucunda elde edilen VKV matrisleri deformasyon analizi gibi jeodezik
çalışmalarda kullanılmaktadır. Bu bağlamda araştırmacılar VKV matrislerini
ölçekleme ihtiyacı hissetmektedirler. Bu çalışmada, Uluslararası GNSS Servis
(International GNSS Service – IGS) ağına ait 10 adet sürekli gözlem yapan sabit
referans istasyonlarının, 2014 yılına ait 11 günlük verileri GIPSY-OASIS II
v6.4 bilimsel yazılımı kullanılarak PPP tekniği ile analiz edilmiştir. 2, 4, 6,
8, 12 ve 24 saatlik gözlem süreleri için GIPSY-OASIS II v6.4 PPP sonuçlarından elde
edilen VKV matrislerine ait ölçek faktörü kestirilmesi amaçlanmıştır. Analiz
sonuçlarına göre ölçek faktörü değerlerinin gözlem süresi arttıkça büyüdüğü
gözlenmiştir.

Keywords

Hassas mutlak konum belirleme, GIPSY-OASIS II v6.4, Varyans kovaryans matrisi, Ölçek faktörü, Güvenirlik

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