GNSS-R DDM Python Simulator – Part 1 – Introduction

GNSS-R is a passive bi-static radar system that takes advantage of the already available signals transmitted by GNSS satellites. The receiver senses the power reflected around each of the transmitter-to-receiver reflection points. These points are referred to as specular points and the area around them is denoted as the glistering zone. For LEO receivers, the area covered by the glistering zone is around 25 km . Receivers can distinguish between different signals using the GNSS transmitter signal modulation which allows to perceive many reflection points with one receiver.

GNSS-R depicted as a multi-static radar system for Earth observations. The receiving satellites are shown as yellow spheres.  The white lines represent direct GNSS signals and the blue lines are ocean surface scattered signals. The lighter blue circles on the Earth surface represent individual samples of the received measurements. Figure extracted from [3]
GNSS-R depicted as a multi-static radar system for Earth observations. The receiving satellites are shown as yellow spheres. The white lines represent direct GNSS signals and the blue lines are ocean surface scattered signals. The lighter blue circles on the Earth surface represent individual samples of the received measurements. Figure extracted from

The reflected signal experiences different time delays and Doppler shifts depending within the glistering zone. This allows to map the received power to these time delays and Doppler shifts. These maps are known as Dopler Delay Maps (DDM) and can be used to study the properties of the reflective surface.

In this post series we will develop a Python simulator for these DDM maps in order to study the reflection perturbation generated by ship wakes received from a High Altitude Pseudo Satellite (HAPS).

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