Direct Signal Enhanced Semicodeless Processing of GNSS Surface-Reflected Signals

Lowe, S.; Meehan, T. K.; Young, Larry

doi:10.1109/jstars.2014.2313061

Cited by 19 publications

(16 citation statements)

References 12 publications

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“…The use of GNSS-R for ocean altimetry was first suggested by Martin-Neira [1993]. Recent enhancements have been proposed, which include the use of wider bandwidth navigation signals [Pascual et al, 2013] and the use of more sophisticated techniques (such as interferometric processing) to process the received waveforms [Cardellach et al, 2013;Lowe et al, 2014;D'Addio et al, 2014].…”

Section: Introductionmentioning

confidence: 99%

First spaceborne observation of sea surface height using GPS‐Reflectometry

Clarizia

Ruf

Cipollini

et al. 2016

Geophysical Research Letters

126

105

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An analysis of spaceborne Global Positioning System reflectometry (GPS‐R) data from the TechDemoSat‐1 (TDS‐1) satellite is carried out to image the ocean sea surface height (SSH). An SSH estimation algorithm is applied to GPS‐R delay waveforms over two regions in the South Atlantic and the North Pacific. Estimates made from TDS‐1 overpasses during a 6 month period are aggregated to produce SSH maps of the two regions. The maps generally agree with the global DTU10 mean sea surface height. The GPS‐R instrument is designed to make bistatic measurements of radar cross section for ocean wind observations, and its altimetric performance is not optimized. The differences observed between measured and DTU10 SSH can be attributed to limitations with the GPS‐R instrument and the lack of precision orbit determination by the TDS‐1 platform. These results represent the first observations of SSH by a spaceborne GPS‐R instrument.

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Section: Introductionmentioning

confidence: 99%

First spaceborne observation of sea surface height using GPS‐Reflectometry

Clarizia

Ruf

Cipollini

et al. 2016

Geophysical Research Letters

126

105

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“…Similarly to the conventional GNSS-R, a third technique known as reconstructed GNSS-R can take advantage of P (Y ) codes being transmitted at L1 and L2 [11], [12]. While it is one of the goals for 3 CAT-2, the description and results presented in the next sections focus on cGNSS-R and iGNSS-R.…”

Section: Implemented Gnss-r Technologiesmentioning

confidence: 99%

Implementation of a GNSS-R Payload Based on Software-Defined Radio for the 3CAT-2 Mission

Olive

Amezaga

Carreño-Luengo

et al. 2016

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

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The 3 CAT-2 nanosatellite aims at demonstrating global navigation satellite system reflectometry (GNSS-R) techniques for spaceborne applications in the small form of a six-unit CubeSat. There are many challenges involved from a size, processing, and power perspectives. The proposed solution for the payload uses a software-defined radio (SDR) connected to a nadir looking array of dual-band and dual-frequency and dual-polarization antennas to capture the reflected GNSS signals and to a zenith looking patch antenna to capture the direct ones. The SDR is controlled by the payload computer, which retrieves the binary samples and processes the raw data to obtain delay-doppler maps (DDMs) via various techniques. DDMs are then compressed using the fully adaptive prediction error coder algorithm, producing an output more suitable for the limited downlink capabilities of these small platforms.

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“…Methodology studies include an investigation of model-free retrieval of sea surface height using a power ratio method combined with cost function optimisation when the sea surface is rather rough [39]. A semi-codeless processing approach [40] showed how to determine the phase sign variation of encrypted P-code GNSS signals and combine it with the CA signal stream to enhance signal to noise ratio in comparison with that achieved by the interferometric method. An investigation of Doppler multilook processing [41] realised enhanced spatial and temporal resolution by intra-and inter-Doppler tracking and averaging of delay waveforms.…”

Section: Ocean Observationmentioning

confidence: 99%

An overview of GNSS remote sensing

Rizos

Burrage

et al. 2014

EURASIP J. Adv. Signal Process.

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The Global Navigation Satellite System (GNSS) signals are always available, globally, and the signal structures are well known, except for those dedicated to military use. They also have some distinctive characteristics, including the use of L-band frequencies, which are particularly suited for remote sensing purposes. The idea of using GNSS signals for remote sensing -the atmosphere, oceans or Earth surface -was first proposed more than two decades ago. Since then, GNSS remote sensing has been intensively investigated in terms of proof of concept studies, signal processing methodologies, theory and algorithm development, and various satellite-borne, airborne and ground-based experiments. It has been demonstrated that GNSS remote sensing can be used as an alternative passive remote sensing technology. Space agencies such as NASA, NOAA, EUMETSAT and ESA have already funded, or will fund in the future, a number of projects/missions which focus on a variety of GNSS remote sensing applications. It is envisaged that GNSS remote sensing can be either exploited to perform remote sensing tasks on an independent basis or combined with other techniques to address more complex applications. This paper provides an overview of the state of the art of this relatively new and, in some respects, underutilised remote sensing technique. Also addressed are relevant challenging issues associated with GNSS remote sensing services and the performance enhancement of GNSS remote sensing to accurately and reliably retrieve a range of geophysical parameters. Review

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Direct Signal Enhanced Semicodeless Processing of GNSS Surface-Reflected Signals

Cited by 19 publications

References 12 publications

First spaceborne observation of sea surface height using GPS‐Reflectometry

First spaceborne observation of sea surface height using GPS‐Reflectometry

Implementation of a GNSS-R Payload Based on Software-Defined Radio for the 3CAT-2 Mission

An overview of GNSS remote sensing

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