A wideband radar depth sounder for measuring the thickness of glacial ice

Abstract

We developed a wideband coherent radar depth sounder (WCORDS) system developed to measure glacial ice thickness and map internal layers with high resolution. The radar operates over a frequency range of 50-200 MHz, providing a resolution of about 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 high sensitivity needed to sound 5-km thick cold ice and map internal layers high resolution. It also consists of a two-channel receiver to obtain very high dynamic range. The low-gain channel is used to map the shallow internal layers and the high-gain channel provides ice sheet thickness and bedrock properties up to a depth of 5000 m. The gain in both the channels can be adjusted to obtain optimum performance. A high-speed data acquisition system is used to digitize and perform necessary real time processing on the data before transferring it to the storage device. The radar and data-acquisition systems have been significantly miniaturized using the latest RF and fabrication technologies. The entire system is designed to fit into multiple compact-PCI cards. Laboratory tests show that the radar system has the required sensitivity to map 5000-m-thick ice. Considerable improvement in sidelobe performance was achieved. The radar system will be tested during the summer 2004 field experiment at the Summit Camp, Greenland.