Instruments and Methods: A Portable Digital Data-Acquisition System for Surface-Based Ice-Radar Studies
Abstract We have built a radio-echo sounder which utilizes a low-frequency broad-band impulse transmitter and a microprocessor-based digital-recording system. The unit is mounted on skis and power is delivered by a small generator and batteries. The receiver uses a portable digital storage oscillosc...
| Published in: | Journal of Glaciology |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
1988
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0022143000007127 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000007127 |
| Summary: | Abstract We have built a radio-echo sounder which utilizes a low-frequency broad-band impulse transmitter and a microprocessor-based digital-recording system. The unit is mounted on skis and power is delivered by a small generator and batteries. The receiver uses a portable digital storage oscilloscope which passes data via a microprocessor unit to a cassette tape for off-line analysis on a personal computer. Though originally intended primarily for sounding temperate ice, the system has been tested in the Antarctic during the 1987–88 field season with good results. The radar performed well there and also in field tests and subsequent studies on South Cascade Glacier, Washington, and many interesting results were obtained. An oblique incidence profile, where transmitter-receiver separation varied, was used to study the dielectric permittivity of the ice and to locate internal layers at shallow depths. The sounder was also deployed in conjunction with hot-water drilling experiments attempting to create cavities at known locations within the ice. Wave forms from different transmitter–receiver orientations around the bore hole were combined in the off-line analysis to produce a more directional synthetic aperture emphasizing returns from the bore-hole region. Changes in the radar echoes from within the ice were not seen during these experiments, possibly because the drilling was not able to create regions with dimensions or orientations approximating those of naturally occurring cavities. |
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