High speed DSP and A to D in an ice radar logging application
For some time the Glaciology section of the Australian Antarctic Division has operated a land-based radar to measure the depth of glacial ice in Antarctica. The radar was mounted on a sled and towed around the Lambert glacier by bulldozer at 5km per hour. High power radio frequency pulses are transm...
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| Format: | Thesis |
| Language: | English |
| Published: |
1999
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| Online Access: | https://eprints.utas.edu.au/19074/ https://eprints.utas.edu.au/19074/1/whole_BrocklesbyAndrewKenneth1999_thesis.pdf |
| Summary: | For some time the Glaciology section of the Australian Antarctic Division has operated a land-based radar to measure the depth of glacial ice in Antarctica. The radar was mounted on a sled and towed around the Lambert glacier by bulldozer at 5km per hour. High power radio frequency pulses are transmitted down into the glacial ice, propagate through the ice and reflect off the bedrock below. The reflected pulses are picked up by a receiver, amplified and passed on to a signal processing section. The waveforms from the signal processing section are logged and displayed. The time taken from pulse transmission to detection, which is proportional to ice depth, may then be obtained. Signal averaging capabilities were required to improve the system signal to noise ratio and enable ice depths of over 3km to be observed. The ground based display and logging system used a digital oscilloscope with signal averaging capabilities to digitise and process incoming radar return echoes. Up to 256 radar return echo waveforms were averaged, the result being displayed and downloaded to an IBM PC via an 1EEE488 link. Future ice depth measurements will involve airborne operations increasing the travelling speed from 5km per hour to 180km per hour. This speed increase will require greater data rates of the display, and logging system In addition the airborne antenna, being carried by a helicopter, is physically smaller than the antenna mounted on the 60 tonne overland system. A smaller antenna leads to smaller antenna effective area, which in turn reduces the radar range. The high-speed digital signal processor (DSP) and high-speed analogue to digital converter (A to D) circuit board forms part of the ice radar display and logging system, replacing the slower digital oscilloscope system. The DSP will have sufficient speed to keep pace with the data rates required for airborne operation and provide improved signal processing power to compensate for reduced radar antenna gain. As no suitable 'off the shelf' product was found the new system would utilise a custom designed high-speed DSP and high-speed A to D converter electronic circuit board. This document concerns the design of a high-speed DSP and A to D circuit board for an ice radar application. |
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