MGEODAR-A Mobile Radar System for Detection and Monitoring of Gravitational Mass-Movements.

Anselm Köhler,Paul V Brennan,Simon Felbermayr,Jan-Thomas Fischer,Lai Bun Lok,Nial Peters

doi:10.3390/s20216373

Abstract

Radar measurements of gravitational mass-movements like snow avalanches have become increasingly important for scientific flow observations, real-time detection and monitoring. Independence of visibility is a main advantage for rapid and reliable detection of those events, and achievable high-resolution imaging proves invaluable for scientific measurements of the complete flow evolution. Existing radar systems are made for either detection with low-resolution or they are large devices and permanently installed at test-sites. We present mGEODAR, a mobile FMCW (frequency modulated continuous wave) radar system for high-resolution measurements and low-resolution gravitational mass-movement detection and monitoring purposes due to a versatile frequency generation scheme. We optimize the performance of different frequency settings with loop cable measurements and show the freespace range sensitivity with data of a car as moving point source. About 15 dB signal-to-noise ratio is achieved for the cable test and about 5 dB or 10 dB for the car in detection and research mode, respectively. By combining continuous recording in the low resolution detection mode with real-time triggering of the high resolution research mode, we expect that mGEODAR enables autonomous measurement campaigns for infrastructure safety and mass-movement research purposes in rapid response to changing weather and snow conditions.

Highlights

Gravitational mass-movements are a major hazard to infrastructure, inhabitants and tourists in mountainous regions
We present a portable FMCW radar which works in a similar fashion to GEODAR
To find optimal settings for the chirp signal f ch and the local oscillator f lo, we vary the settings of the direct digital synthesiser (DDS) and the local oscillator according to the desired transmit frequencies ( f tx = f ch + f lo )

Summary

Introduction

Gravitational mass-movements are a major hazard to infrastructure, inhabitants and tourists in mountainous regions. Real-time detection of avalanches is advantageous as it allows safety measures to be implemented only when needed, for example closing a road using traffic lights when mass movements like snow avalanches are detected on the mountain flank above Such real-time detection uses seismic or infrasound sensors in close proximity to the avalanche flow or radar technology that can observe the avalanche path from a stand-off distance. Modern radars for avalanche detection utilize the Doppler effect, they send pulses that estimate the range by time of flight analysis Those pulse-Doppler radars can achieve a range resolution on the 10 m scale, and within these range gates a complete velocity spectrum up to 100 m/s is measured [2]. While such pulse-Doppler radars are effective for movement detection, they lack high spatial resolution, limiting their application for detailed scientific studies on the flow dynamics

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