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Detecting Targets above the Earth’s Surface Using GNSS-R Delay Doppler Maps: Results from TDS-1

School of Engineering and Information Technology, University of New South Wales, 2612 Canberra, Australia
Department of Physics, Univeristat Politecnica de Catalunya, 08034 Barcelona, Spain
Department of Signal Theory and Communications, Universitat Politecnica de Caltalunya and IEEC/UPC, 08034 Barcelona, Spain
School of Civil and Environmental Engineering, University of New South Wales, 2052 Sydney, Australia
Author to whom correspondence should be addressed.
Remote Sens. 2019, 11(19), 2327;
Received: 12 August 2019 / Revised: 3 October 2019 / Accepted: 4 October 2019 / Published: 7 October 2019
(This article belongs to the Special Issue Applications of GNSS Reflectometry for Earth Observation)
Global Navigation Satellite System (GNSS) reflected signals can be used to remotely sense the Earth’s surface, known as GNSS reflectometry (GNSS-R). The GNSS-R technique has been applied to numerous areas, such as the retrieval of wind speed, and the detection of Earth surface objects. This work proposes a new application of GNSS-R, namely to detect objects above the Earth’s surface, such as low Earth orbit (LEO) satellites. To discuss its feasibility, 14 delay Doppler maps (DDMs) are first presented which contain unusually bright reflected signals as delays shorter than the specular reflection point over the Earth’s surface. Then, seven possible causes of these anomalies are analysed, reaching the conclusion that the anomalies are likely due to the signals being reflected from objects above the Earth’s surface. Next, the positions of the objects are calculated using the delay and Doppler information, and an appropriate geometry assumption. After that, suspect satellite objects are searched in the satellite database from Union of Concerned Scientists (UCS). Finally, three objects have been found to match the delay and Doppler conditions. In the absence of other reasons for these anomalies, GNSS-R could potentially be used to detect some objects above the Earth’s surface. View Full-Text
Keywords: GNSS reflectometry; delay Doppler map; target detection GNSS reflectometry; delay Doppler map; target detection
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MDPI and ACS Style

Hu, C.; Benson, C.; Park, H.; Camps, A.; Qiao, L.; Rizos, C. Detecting Targets above the Earth’s Surface Using GNSS-R Delay Doppler Maps: Results from TDS-1. Remote Sens. 2019, 11, 2327.

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