| Abstract: | The Earthworm system is a seismic network data acquisition and processing system used by the Northern California Seismic Network as well as many other seismic networks. The input to the system is comprised of many realtime electronic waveforms fed to a multi-channel digitizer on a PC platform. The digitizer consists of one or more National Instruments Corp. AMUX?64T multiplexer boards attached to an A/D converter board located in the computer. Originally, passive filters were installed on the multiplexers to eliminate electronic noise picked up in cabling. It was later discovered that a small amount of crosstalk occurred between successive channels in the digitizing sequence. Though small, this crosstalk will cause what appear to be small earthquake arrivals at the wrong time on some channels. This can result in erroneous calculation of earthquake arrival times, particularly by automated algorithms. To deal with this problem, an Earthworm filter board was developed to provide the needed filtering while eliminating crosstalk. This report describes the tests performed to find a suitable solution, and the design of the circuit board. Also included are all the details needed to build and install this board in an Earthworm system or any other system using the AMUX?64T board. Available below is the report in PDF format as well as an archive file containing the circuit board manufacturing information. |
| Genre: | USGS Numbered Series |
| ProdID: | 23467 |
| Citation Author: | Jensen, Edward Gray |
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| Citation Edition: | Version 1.0. |
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| Citation Language: | ENGLISH |
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| Citation No Pagination: | Y |
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| Citation Phsyical Description: | NA |
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| Citation Publisher: | U.S. Department of the Interior, U.S. Geological Survey, |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 2000-379 |
| Citation Search Results Text: | A filter circuit board for the Earthworm Seismic Data Acquisition System; 2000; OFR; 2000-379; Jensen, Edward Gray |
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| Citation Year: | 2000 |
| Type: | citation/reference |
| Text: | A filter circuit board for the Earthworm Seismic Data Acquisition System; 2000; OFR; 2000-379; Jensen, Edward Gray |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/usgs_thumb.jpg |
| URL (INDEX PAGE): | http://geopubs.wr.usgs.gov/open-file/of00-379/ |
| Date Other: | Wed, 1 May 2002 00:00 -0500 |
| Publisher: | U.S. Department of the Interior, U.S. Geological Survey, |
