Design and Development of a Wideband Coherent Radar Depth Sounder

Sea level rise is an important indicator of global climate change. Sea level has been increasing at about 2mm/year over the past century and may continue to do so. The continuing rise in sea level will have a devastating impact on humanity as approximately 60% of people on this planet live in the coastal regions. The polar ice sheets, which account for 80% of earth’s fresh water supply are a major source of sea level rise. A key to quantifying their contribution is an accurate determination of the mass balance of these ice sheets. Ice thickness is an important parameter required to estimate the mass balance of the ice sheet and to study ice dynamics. Depth sounding radars designed at RSL/KU have been successful in measuring the ice thickness for the past 10 years. A Wideband Coherent Radar Depth Sounder System has been developed to obtain better delineation of the internal layers and information about the bedrock properties. The radar operates over a frequency range of 50-200 MHz, providing a resolution of less than 1 m in ice. A high speed Arbitrary Waveform Generator (AWG) is used to generate a chirp from 50-200 MHz over a very small pulse width to obtain large unambiguous range and the maximum number of integrations. Two gain channels are incorporated into the receiver to obtain very high dynamic range. The low gain channel is used to map the shallow internal layers and the HGC provides ice sheet thickness and bedrock properties up to a depth of 4500 m. The gain in both the channels can be altered depending on the operating mode, ice thickness, and