Space-to-space Radio Interferometry System from Medium Earth Orbits

Martín-Neira, Manuel; Kudriashov, Volodymyr; Barat, Itziar; Duesmann, Berthyl; Daganzo, E.

doi:10.11728/cjss2019.04.544

Cited by 17 publications

(22 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Over land, because of the slopes of the terrain, it may happen that there are multiple reflection points, but they are typically clustered around the specular point one would find when removing those slopes. It is important to understand that GNSS-R has developed in this way, that is, by exploiting signals reflected at and around the specular point, as proposed by Martin-Neira (1993). Signals scattered from the points far away from the specular point have generally too low power to be useful for retrievals and therefore are not used.…”

Section: Theory and Methodsmentioning

confidence: 99%

“…In 1988, Hall and Cordey (1988) firstly proposed the use of GPS reflected signals for scatterometry applications. Later on, GPS reflection measurement was first proposed for altimetry by the European Space Agency (ESA) scientist Manuel Martin-Neirai in 1993, that is, the GPS surface reflection signal and the direct signal are received by the receiver together, and the delay between them can be used for altimetry applications (Martin-Neira, 1993), namely Passive Reflectometry and Interferometry System (PARIS). In 1994, French scientists published the results that accidentally a receiver locked to sea surface reflected signals during a flight test, but because of its impact on positioning accuracy, it is usually rejected as a multipath signal (Auber et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Remote sensing and its applications using GNSS reflected signals: advances and prospects

Jin,

Camps,

Jia

et al. 2024

Satell Navig

View full text Add to dashboard Cite

The Global Navigation Satellite Systems (GNSS), including the US’s GPS, China’s BDS, the European Union’s Galileo, and Russia’s GLONASS, offer real-time, all-weather, any-time, anywhere and high precision observations by transmitting L band signals continuously, which have been widely used for positioning, navigation and timing. With the development of GNSS technology, it has been found that GNSS-reflected signals can be used to detect Earth’s surface characteristics together with other signals of opportunity. In this paper, the current status and latest advances are presented on Global Navigation Satellite System-Reflectometry (GNSS-R) in theory, methods, techniques and observations. New developments and progresses in GNSS-R instruments, theoretical modeling, and signal processing, ground and space-/air-borne experiments, parameters retrieval (e.g. wind speed, sea surface height, soil moisture, ice thickness), sea surface altimetry and applications in the atmosphere, oceans, land, vegetation, and cryosphere are given and reviewed in details. Meanwhile, the challenges in the GNSS-R development of each field are also given. Finally, the future applications and prospects of GNSS-R are discussed, including multi-GNSS reflectometry, new GNSS-R receivers, GNSS-R missions, and emerging applications, such as mesoscale ocean eddies, ocean phytoplankton blooms, microplastics detection, target recognition, river flow, desert studies, natural hazards and landslides monitoring.

show abstract

Section: Theory and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Remote sensing and its applications using GNSS reflected signals: advances and prospects

Jin,

Camps,

Jia

et al. 2024

Satell Navig

View full text Add to dashboard Cite

show abstract

“…Since the time remote sensing using earth reflected Global Positioning System (GPS) signals was conceived, e.g., [6], [7], numerous ground-based and airborne experiments have been conducted to demonstrate its feasibility, e.g., [8]- [10]. In 2003, the first spaceborne GNSS-R demonstration experiment onboard the UK disaster monitoring constellation (DMC) satellite, was performed [11].…”

Section: Introductionmentioning

confidence: 99%

Coherent Combination of GPS III L1 C/A and L1C Signals for GNSS Reflectometry

Du,

Nan,

et al. 2024

IEEE Trans. Geosci. Remote Sensing

View full text Add to dashboard Cite

With the evolution of Global Navigation Satellite System (GNSS), more GNSS satellites and civilian signals are available for GNSS Reflectometry (GNSS-R). Developments of new onboard processing strategies can improve the observation performance of spaceborne GNSS-R. To this end, this article proposes a new processing method by coherently combining reflected Global Positioning System (GPS) III L1 C/A and L1C signals. By exploiting the additional signal component, the signalto-noise ratio of the reflected signal can be significantly improved. Moreover, taking advantage of the narrower auto-correlation function of the combined signal, the spatial resolution and the performance on geophysical applications can be significantly improved. The proposed method has been validated by processing cyclone GNSS (CYGNSS) raw intermediate frequency data including the direct and reflected signals from GPS III satellites. The results indicate that the signal-to-noise ratio (SNR) of the combined reflected waveform can be improved by ∼2 dB compared to the L1 C/A waveform. Moreover, the SNR of the combined signal can be improved more efficiently using a longer coherent integration interval compared to the L1 C/A signal. Preliminary altimetric results demonstrate a 35.3%-61.6% improvement in the ranging standard deviation, and a 22.4%-64.4% improvement in the median absolute deviation, compared to L1 C/A measurements. Additionally, the correlation coefficient between combined measurements and wind speed improves by 26.3% on average compared to L1 C/A measurements, and 45.7% for high winds. This article presents a novel GNSS-R onboard signal processing method with improved performance, which can provide a reference for the design of future GNSS-R instruments.

show abstract

“…GNSS signals are used in Remote Sensing as SoOp for Radio Occultations (GNSS-RO) [46,47] and Reflectometry (GNSS-R). The GNSS-R concept was proposed for the first time in 1988 as a multi-static scatterometer [48], and later on in 1993 for sea altimetry [49], using a method called now interferometric GNSS-R (iGNSS-R), which consists of crosscorrelating the direct signal with the reflected one. In that way, military codes, which provide a better spatial resolution, could also be used without knowing them.…”

Section: Gnss-rmentioning

confidence: 99%

“…The spatial resolution of GNSS-R has been already analyzed in several works. In [116], it is presented that the spatial resolution for an iGNSS-R altimeter was about 36 km to 54 km from an altitude of 450 km, at incidence angles ranging from 90º to 40º, respectively. Years later, in [117], the spatial resolution definition was re-defined as "effective" spatial resolution, now taking into account both the geometry and the delay-Doppler interval.…”

Section: Introductionmentioning

confidence: 99%

Development of novel instruments and techniques for passive microwave remote sensing

Muñoz Martin

View full text Add to dashboard Cite

Earth Observation using satellites has helped to better model our planet. The goal of such systems is to provide large data sets to help to understand the effects of our actions on the climate, to predict storms in near real-time, to prevent forest fires, or to prevent desertification, among others. In the last years, thanks to the miniaturization of electronics a new type of satellite have become popular, the CubeSat, a small spacecraft weighing from 1 to 10 kg, which can carry different types of instruments. Thanks to the cost reduction of these new platforms, new techniques can be easily evaluated, and the concept of a mesh of sensors surrounding the Earth is becoming a reality. Besides, the suitability of new techniques is being proven for such small spacecraft, such as GNSS reflectometry (GNSS-R). GNSS-R instruments are typically cheaper, more efficient (in terms of power consumption), and smaller than their traditional equivalent ones. This Ph.D. thesis is devoted to the development of passive microwave remote sensing instruments for CubeSats. However, before entering into the instrument design, several field experiments were proposed to model and validate the use of GNSS-R under different conditions. This Ph.D. thesis is divided into three main parts. The first part is devoted to assessing the capabilities of GNSS-R to retrieve different geophysical parameters through a different set of field experiments. First, the achievable spatial resolution of L1 and L5 GNSS-R signals is analyzed under different conditions. Second, taking into account the incoherent integration limits previously analyzed, the coherency of GNSS-R signals is analyzed at L1 and L5 bands. Third, thanks to the use of short integration times, multiple reflections received in the GPS L5 reflected signal could be identified as multiple peaks, thanks to the narrower auto-correlation function of such signals. Over the ocean, these multiple peaks are analyzed and linked to the sea state. Over the Australian rainforest, these multiple peaks at L5 are linked to multiple reflections on top of the vegetation canopy and in the bare soil. Fourth, a methodology to estimate soil moisture content over land using GNSS-R signals is proposed. Finally, the use of GNSS-R signals to estimate sea-ice thickness and snow content over the sea-ice is examined thanks to the data collected by a circular polarization GNSS-R instrument part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. The second part of this dissertation is devoted to the design, implementation, and test of three passive microwave instruments for CubeSats. First, the Flexible Microwave Payload -1 (FMPL-1) is proposed as part of the 3Cat-4 mission. The instrument includes three experiments in a single platform: a total power L-band radiometer with frequent internal calibration, an L1/L2 GNSS reflectometer, and an AIS receiver. Second, the FMPL-2 instrument is proposed as the main payload of the 3Cat-5/A, one of the two instruments composing the ESA FSSCat mission, the first third-party mission contributing to the Copernicus system based on CubeSats. This second instrument is the evolved version of FMPL-1 and can provide synchronous GNSS-R and L-band radiometry data. Finally, a third instrument, the FMPL-3, is proposed for the GNSSaS mission of the NSSTC from the UAE. This third instrument includes the first-ever GNSS-R receiver at L5 and aims to prove the capabilities of such signals from space. Finally, in the third part, the first results of FMPL-2 are presented and analyzed. The instrument was successfully launched into a Low Earth Orbit during the Vega VV16 flight. First, the results of FMPL-2 during the first two weeks of in-orbit validation are presented. Data-driven algorithms to estimate sea-ice concentration, thickness, and soil moisture content over land are implemented using L-band microwave radiometry data and GNSS-R data retrieved by FMPL-2. iL'observació de la Terra mitjançant satèl·lits ha ajudat a modelar millor el nostre planeta. L'objectiu d'aquests sistemes és proporcionar grans conjunts de dades que ajudin a comprendre els efectes de les nostres accions sobre el clima, a predir tempestes gairebé en temps real, o a prevenir incendis forestals o a prevenir la desertificació, entre d’altres. En els darrers anys, gràcies a la miniaturització de l’electrònica, s’ha popularitzat un nou tipus de satèl·lit, el CubeSat, un petit satèl·lit que pesa menys de 10 kg i que pot transportar diferents tipus d’instruments. Gràcies a la reducció de costos d'aquestes noves plataformes, es poden avaluar fàcilment noves tècniques, com ara la reflectometria GNSS (GNSS-R). Els instruments GNSS-R solen ser més econòmics, més eficients (en termes de consum d’energia) i més petits que els equivalents tradicionals. Aquest doctorat la tesi es dedica al desenvolupament d'instruments de teledetecció passiva per microones per a CubeSats. No obstant això, abans d’entrar en el disseny de l’instrument, es van proposar diversos experiments de camp per modelar i validar l’ús de GNSS-R en diferents condicions. Aquesta tesi es divideix en tres parts principals. La primera part es dedica a avaluar les capacitats de GNSS-R per recuperar diferents paràmetres geofísics mitjançant un conjunt diferent d’experiments de camp. En primer lloc, s’analitza la resolució espacial assolible dels senyals GNSS-R L1 i L5 en diferents condicions. En segon lloc, tenint en compte els límits d’integració incoherents analitzats prèviament, s’analitza la coherència dels senyals GNSS-R a les bandes L1 i L5. En tercer lloc, gràcies a l’ús de curts temps d’integració, les múltiples reflexions rebudes al senyal reflectit GPS L5 s'identifiquen com a múltiples pics. Sobre l’oceà, aquests múltiples pics s’analitzen i es relacionen amb l’estat del mar. A la selva tropical australiana, aquests múltiples pics a L5 es relacionen amb múltiples reflexions a la part superior de la vegetació i al sòl nu. En quart lloc, es proposa una metodologia per estimar el contingut d’humitat del sòl sobre la terra mitjançant senyals GNSS-R. Finalment, l’ús de senyals GNSS-R per estimar el gruix del gel marí i el contingut de neu sobre el gel marí s’examina gràcies a les dades recollides per un instrument GNSS-R de polarització circular que forma part d'expedició "MOSAiC". La segona part d'aquesta dissertació es dedica al disseny, implementació i prova de tres instruments de microones passius per a CubeSats. En primer lloc, es proposa la FMPL-1 com a part de la missió 3Cat-4. L'instrument inclou tres experiments en una única plataforma: un radiòmetre de banda L de potència total amb un calibratge intern freqüent, un reflectòmetre GNSS L1/L2 i un receptor AIS. En segon lloc, es proposa l’instrument FMPL-2 com a principal càrrega útil del 3Cat-5/A, un dels dos instruments que componen la missió FSSCat de la ESA, la primera missió subcontractada basada en CubeSats que contribueix al sistema Copernicus. Aquest segon instrument és la versió evolucionada de FMPL-1 i pot proporcionar dades de radiometria GNSS-R i de banda L síncronament. Finalment, es proposa un tercer instrument, el FMPL-3, per a la missió GNSSaS del NSSTC dels Emirats Àrabs Units. Aquest tercer instrument inclou el primer receptor GNSS-R de L5 i pretén demostrar les capacitats d’aquests senyals des de l’espai. Finalment, a la tercera part es presenten i analitzen els primers resultats de FMPL-2. L'instrument es va llançar amb èxit a una òrbita terrestre baixa durant el vol Vega VV16. En primer lloc, es presenten els resultats de FMPL-2 durant les dues primeres setmanes de validació en òrbita. Algoritmes basats en dades per estimar la concentració i el gruix del gel oceànic, i el contingut d’humitat sobre la terra s'implementen mitjançant dades de radiòmetre

show abstract

Space-to-space Radio Interferometry System from Medium Earth Orbits

Cited by 17 publications

References 7 publications

Remote sensing and its applications using GNSS reflected signals: advances and prospects

Remote sensing and its applications using GNSS reflected signals: advances and prospects

Coherent Combination of GPS III L1 C/A and L1C Signals for GNSS Reflectometry

Development of novel instruments and techniques for passive microwave remote sensing

Contact Info

Product

Resources

About