Angle Dependence Analysis Method to Determine SNR Arc Applied to GNSS-MR Sea Level Retrieval

doi:10.11947/j.JGGS.2021.0202

Abstract

Abstract:

The Global Navigation Satellite Systems (GNSS) broadcast radio signals are continuously at two or more frequencies in the L-band, and the multipath signals from sea surface recorded by off-the-shelf geodetic receivers have been demonstrated they can be used to estimate sea level, using a technology called GNSS multipath reflectometry (GNSS-MR). Before proceeding to estimate reflection parameters, the azimuth range and elevation angle range are needed to be defined, as only with suitable azimuths and elevation angles the sensing zones can be guaranteed on water. So, this study presents an angle dependence analysis method to jointly select the azimuth range and elevation angle range based on wavelet analysis which can describe the non-stationary power of different sinusoidal oscillations changed with elevation angle. The key of this method is to use one grid model to screen the spectrum power of multipath oscillation on different elevation angles and azimuths in this work. Then the elevation angles and the azimuths can be determined by searching grids with greater power. The GPS and GLONASS data of two Multi-GNSS Experiment (MGEX) stations named BRST and MAYG was analyzed and used to retrieve. Firstly, the angle dependence analysis was carried out to determine the elevation range and azimuth range. Secondly, the sea levels were retrieved from individual signals. Finally, the retrievals of individual signals are combined to form a 10-min sea level retrieval series. The RMSEs of the combined retrievals are both less than 15cm. The results show the effectiveness of the selection of angle range based on the angle dependence analysis method.

Key words: GNSS-MR; sea level; azimuth determination; elevation angle determination; multi-GNSS combination

Xiaolei WANG,Xiufeng HE,Qin ZHANG,Mingfeng SONG,Zijin NIU. Angle Dependence Analysis Method to Determine SNR Arc Applied to GNSS-MR Sea Level Retrieval[J]. Journal of Geodesy and Geoinformation Science, 2021, 4(2): 14-26.

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Satellite system	Frequency band	Frequency	Channel/ Code	SNR type
GPS	L1	1575.42	C/A	S1C
	L2	1227.60	Z-tracking and similar (AS on)	S2W
	L2	1227.60	L2C(M+L)	S2X
	L5	1176.45	I+Q	S5X
GLONASS	G1	1602+k*9/16 k=-7…+12	C/A	S1C
	G1	1602+k*9/16 k=-7…+12	P	S1P
	G2	1246+k*7/16	C/A	S2C
	G2	1246+k*7/16	P	S2P

Site	System	Type	Number /d	RMSE /cm	CORR /(%)
BRST	GPS	S1C	33.17	48.39	97.39
		S2W	22.25	49.74	96.80
		S2X	12.25	45.10	97.17
		S5X	9.17	35.39	98.51
	GLONASS	S1C	25.25	32.55	98.92
		S1P	24.75	34.57	98.55
		S2C	24.08	36.98	98.33
		S2P	26.42	30.34	99.07
MAYG	GPS	S1C	21.25	54.91	82.46
		S2W	20.13	39.19	92.33
		S2X	14.06	30.04	97.61
		S5X	8.36	26.02	98.85
	GLONASS	S1C	19.75	47.27	86.13
		S1P	19.75	43.66	87.59
		S2C	18.06	38.16	93.72
		S2P	14.94	37.12	93.63