نتایج جستجو برای: gnss

تعداد نتایج: 6198  

2014
Erin Griggs E. Robert Kursinski Dennis Akos

GNSS RO utilizes the various navigation satellite systems as signal sources for atmospheric remote sensing. The frequency stability of the signals emitted by GNSS satellites is tied to the stability of the atomic frequency standards (AFS) they carry onboard and is thus critical to the quality of the atmospheric profiles derived from the occultation measurements. Because of the variety of AFS us...

2011
P. D. Solomon J. Wang

Unmanned Aerial Vehicle (UAV) technology is now commonplace in many defence and civilian environments. However, the high cost of owning and operating a sophisticated UAV has slowed their adoption in many commercial markets. Universities and research groups are actively experimenting with UAVs to further develop the technology, particularly for automated flying operations. The two main UAV platf...

2014
Xuerui Wu Shuanggen Jin

Nowadays, GNSS-Reflectometry (GNSS-R) can be a new promising remote sensing tool in the ocean, snow/ice and land surfaces, e.g., vegetation biomass monitoring. Although GNSS-R provides a potentially special L-band multi-angular and multi-polarization measurement, the theoretical vegetation scattering properties and mechanisms for GNSS-R are not understood clearly. In this paper, the GNSS-R vege...

2013
Paul Craven Ronald Wong

Global Navigation Satellite System (GNSS) signals, such as those from United States Global Positioning System (GPS), Europe’s Galileo, and Russia’s Global Navigation Satellite System (GLONASS), typically have extremely low received signal strengths at the Earth’s surface and are therefore susceptible to a range of interference signals. Such interference examples include, but not limited to, int...

Journal: :ISPRS Int. J. Geo-Information 2015
Conor Cahalane

The number of satellites visible to a Global Navigation Satellite System (GNSS) receiver is important for high accuracy surveys. To aid with this, there are software packages capable of predicting GNSS visibility at any location of the globe at any time of day. These prediction packages operate by using regularly updated almanacs containing positional data for all navigation satellites; however...

2009
Antonio Rius Estel Cardellach

The Global Navigation Satellite Systems (GNSS) transmit L-band signals (see the Reference [1]). The GNSS receivers, as its main objective, measure the time elapsed from the transmission to the reception of L Band signals to infer the distance transmitter-receiver and to derive the three coordinates and time status of the receiver. The same signals could be recorded after its reflection on the E...

تعیین دقیق پارامترهای سرعت و جهت جریان‌های دریایی از مسائل مهمی است که در مطالعات دریایی مورد توجه قرار می گیرد که بدین منظور می بایست از جریان‌سنج‌های دقیق و کالیبره استفاده شود. پارامتر جهت یا همان هدینگ حاصل از جریان سنج‌های دریایی که بوسیله‌ی قطب نمای نصب شده بر روی آنها تعیین می‌شود، همانند پارامتر سرعت می‌بایست به طور صحیح مورد بررسی قرار گرفته و خطای آن محاسبه شود. در این مقاله از گیرنده...

2007
Di Li

Application of MEMS sensor in navigation is increasingly becoming important due to its advantages in terms of the quickly improving precision, robustness, high dynamic response and lower costs of development and usage. Moreover by employing the optimal estimation technique of Kalman filtering, the performance of MEMS based INS has been greatly enhanced by the integration of GNSS. This paper foc...

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