Precision Bounds in GNSS-R Ocean Altimetry

Pascual, Daniel; Camps, Adriano; Martín, Francisco; Park, Hyuk; Alonso-Arroyo, A.; Onrubia, R.

doi:10.1109/jstars.2014.2303251

Cited by 46 publications

(41 citation statements)

References 18 publications

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“…It is worth mentioning that the SNR decreases with the receiver bandwidth, as the thermal noise power is proportional to the latter. The same effect of the receiver bandwidth on the SNR was also reported in [28]. …”

Section: Signal To Thermal Noise Ratiosupporting

confidence: 74%

“…In [17,28], comprehensive models were proposed based on the Cramer-Rao Bound (CRB). In this work, a simpler and effective model proposed in [13] is adopted, in which the altimetric precision σ h is expressed as a function of the SNR, the altimetric sensitivity, the number of samples incoherently averaged N inc and the elevation angle θ SP as…”

Section: Precision Analysismentioning

confidence: 99%

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The Impact of Inter-Modulation Components on Interferometric GNSS-Reflectometry

Rius

Fabra

et al. 2016

Remote Sensing

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Abstract:The interferometric Global Navigation Satellite System Reflectometry (iGNSS-R) exploits the full spectrum of the transmitted GNSS signal to improve the ranging performance for sea surface height applications. The Inter-Modulation (IM) component of the GNSS signals is an additional component that keeps the power envelope of the composite signals constant. This extra component has been neglected in previous studies on iGNSS-R, in both modelling and instrumentation. This letter takes the GPS L1 signal as an example to analyse the impact of the IM component on iGNSS-R ocean altimetry, including signal-to-noise ratio, the altimetric sensitivity and the final altimetric precision. Analytical results show that previous estimates of the final altimetric precision were underestimated by a factor of 1.5∼1.7 due to the negligence of the IM component, which should be taken into account in proper design of the future spaceborne iGNSS-R altimetry missions.

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Section: Signal To Thermal Noise Ratiosupporting

confidence: 74%

Section: Precision Analysismentioning

confidence: 99%

The Impact of Inter-Modulation Components on Interferometric GNSS-Reflectometry

Rius

Fabra

et al. 2016

Remote Sensing

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“…SSC values between the main GNSS codes are shown in Table I Table II for lower L-band (1164-1300 MHz). These values have been obtained using (12), and taking B r equal to the main lobe bandwidth as in [23].…”

Section: A Ssc Valuesmentioning

confidence: 99%

“…Indeed, the last ones correspond to the auto-correlation functions of the input signals using correlator defined in (3) as was done in [18]. Therefore, if x and y are already taken windowed by T c and delayed by τ , χ xx = χ xx , χ yy = χ yy , and (27) is equivalent to (23). Henceforth, this last statement will be assumed.…”

Section: Ieee Journal Of Selected Topics In Applied Earth Observationmentioning

confidence: 99%

SNR Degradation in GNSS-R Measurements Under the Effects of Radio-Frequency Interference

Querol

Alonso-Arroyo

Onrubia

et al. 2016

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…Assuming that coherent scattering is negligible, the bistatic scattering coefficient was derived under the geometric optics limit, for a sea surface model with Gaussian distribution of the slopes, and a final expression of the "waveform" was derived. During the last decade, additional experimental [5][6][7][8] and theoretical [9][10][11][12] works have been performed to investigate the feasibility of this bistatic radar system to perform accurate ocean altimetry, usually with open-loop receivers, and using a model of the scattering geometry to center the delay and Doppler tracking windows.…”

Section: Introductionmentioning

confidence: 99%

Empirical Results of a Surface-Level GNSS-R Experiment in a Wave Channel

Carreño-Luengo

Camps

2015

Remote Sensing

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Abstract:The scattering of GNSS signals over a water surface is studied when the receiver is at a low height, as in GNSS-R coastal altimetry. The precise determination of the local sea level and wave state from the coast will provide useful altimetry and wave information as "dry" tide and wave gauges. An experiment has been conducted at the Canal d'Investigació i Experimentació Marí tima (CIEM) wave channel for two simulated "sea" states. The GNSS-reflectometer used is the P(Y) and C/A ReflectOmeter (PYCARO) instrument, a closed-loop receiver with delay and Doppler tracking loops that uses the conventional GNSS-R technique for the GPS C/A code. After retracking of the scattered GPS signals, the coherent and incoherent components have been studied. To reproduce the transmitted GPS signals indoors, a Rohde and Schwarz signal generator is used. It is found that, despite the ratio of the coherent and incoherent components being ~1, the coherent component is strong enough that it can be tracked. The coherent component comes from clusters of points on the surface that approximately satisfy the specular reflection conditions ("roughed facet"). The Pearson's linear correlation coefficients of the derived "sea" surface height with the wave gauge data are: 0.78, 0.85 and 0.81 for a SWH = 36 cm and 0.34, 0.74, and 0.72 for a SWH = 64 cm, respectively, for transmitter elevation angles of θ e = 60°, 75° and 86°, respectively. Finally, the rms phase of the received signal before the retracking processing is used to estimate the effective rms surface height of the 'facets', where the waves get scattered. It is found to be between 2.5-and 4.1-times smaller than the theoretical values corresponding to the half of the coherent reflectivity decaying factor.

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Precision Bounds in GNSS-R Ocean Altimetry

Cited by 46 publications

References 18 publications

The Impact of Inter-Modulation Components on Interferometric GNSS-Reflectometry

The Impact of Inter-Modulation Components on Interferometric GNSS-Reflectometry

SNR Degradation in GNSS-R Measurements Under the Effects of Radio-Frequency Interference

Empirical Results of a Surface-Level GNSS-R Experiment in a Wave Channel

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