Geodesy and mine survey
The paper considers methods of height determination on marine topographic surface (STS) by means of GNSS receivers that receive direct and reflected electromagnetic signals from the STS using the GNSS reflectometry (GNSS-R). It gives a brief analysis of GNSS-R methods, configuration of receivers and antennae, used in Russia and abroad, and describes the experience of GNSS-R method application in Russia and abroad. The results of abroad experiments demonstrated that the use of the interferometric version of the GNSS-R method based on the «signal-to-noise ratio» allows to determine STS height with an error of up to 1,53 cm, however for this accurate detection of the electromagnetic signal displacement is required. Application of GNSS-R «phase delay» method allows determining the STS height with error of 1-2 cm. The main observable parameter in the interferometric GNSS-R method using signal-to-noise ratio is the mutual coherence, or cross-correlation of two separate GNSS signals created coherently by a single GNSS transmitter and collected by a single instrument i.e. a GNSS-R receiver. A GNSS-R receiver based on the measurement of the coherence of the reflected and direct beams is named interferometric or codeless. If a model of the code of the transmitted signal is known, then the direct signal could be substituted by its known functional representation. The methods of GNSS-R in Russia for determination of height STS are not sufficiently investigated. The available amount of experimental data on the works carried out in Russia does not allow us to make specific conclusions about the applicability of the GNSS-P method to determine the heights of the marine topographic surface with reliable accuracy.
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