Wang, L.; (2012) Avalanche imaging radar. Doctoral thesis , UCL (University College London).

Abstract

Over the past century, due to the significant increase in recreational activities, transportation, construction in high altitude areas, mountain areas all around the world, have been seen substantial development. In these high altitude areas around mountain ranges, avalanche always brings huge threaten to human’s activities and lives. The rising demand for higher safety measures has given new pressure to the development of mitigation technology to protect human in certain areas, and driven rise to a new scientific area entirely devoted to avalanche. A RADAR system can provide superior penetration capability through any type of weather condition, and can be used in the day or night time. A RADAR system uses electromagnetic wave that does not require a medium like Sonar that is using water as medium. Radar also can be long range, because the electromagnetic wave is able to propagate at the speed of light. It is less susceptible to weather conditions compared with Lasers. It does not require target cooperation to emit any signals. The original contribution of this thesis contains four parts: the novel work of snow particles models (option models and HFT model); the simulation of a receiver module in an avalanche radar system; the development of an active baseband filter; and the development of an FPGA chirp generator. The option model and HFT model are built to give solutions and to map and predict the moving route of snow particles. The purposes of proposing these two models are different and the assumptions of both totally diverge. The option model is built on the assumption of knowing all the information about the stop location and start location of an airborne avalanche. The key concept of the option model is the introduction of a binary tree. By using the theories of a binary tree, normal distribution and the knowledge of the stop location and start location of an airborne avalanche, its route can be mapped and the behaviour can be further studied. On the other hand, an HFT model is based on the theories of stochastic process. It does not require any knowledge of the avalanches and can be used to predict the movement of an airborne avalanche. The FPGA chirp generator is built for more flexibility than the DDS waveform generator. The simulation is done in this thesis to help design the receiver module in avalanche radar. And the prototype of the FPGA chirp generator is based on Xilinx virtex-5 development board and avanet high-speed DAC. This new design is different from existing FPGA chirp generator, since it uses the onboard memory to store the chirp signal data, which gives the ability to store more data to significantly increase the sampling rate and resolution of chirp signal.

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