Electrical computers: arithmetic processing and calculating – Electrical digital calculating computer – Particular function performed
Reexamination Certificate
1998-09-16
2001-11-13
Mai, Tan V. (Department: 2121)
Electrical computers: arithmetic processing and calculating
Electrical digital calculating computer
Particular function performed
C708S316000
Reexamination Certificate
active
06317765
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to filters and, more particularly, to decimation digital filters which utilize a plurality of sinc filters selectively arranged in combination in a pipe line fashion to provide a desired decimation ratio.
2. Description of Related Art
Systems for conducting seismic exploration are well known in the art. On land, a plurality of transducers are deployed over a region and configured to receive reflections of acoustic signals from different geophysical layers beneath the surface of the earth. Seismic sensors are connected over cables to signal conditioning, digitization and digital recording equipment. When utilizing a seismic system, a strong acoustic signal is generated by, for example, setting off an explosion or by utilizing an acoustic signal generator having a relatively high power output. Reflections of the acoustic signals from the geophysical layers are then received at the seismic sensors deployed over a given area and the signals recorded, typically, for later analysis.
One problem with seismic exploration is that it frequently occurs in remote areas. Once sensors are deployed over a large area and seismic data gathered, great expense would be incurred if data were corrupted by malfunctioning sensors or electronics and a seismic survey crew needed to return again to the site, set up equipment and re-gather the data.
Seismic exploration has exacting requirements for seismic sensors and for the electronics which processes the signals derived from seismic sensors. There is therefore a need to be able to test both the sensors and related equipment to ensure that both the devices and the associated electronics are functioning properly. It is important that the seismic data gathering equipment be able to synchronize the data gathered with the explosion used for a measurement. This is somewhat difficult when the timing of the explosion with respect to the triggering signal is unpredictable, as it is with, for example, dynamite.
SUMMARY OF THE INVENTION
The invention is directed to a decimation filter which implements selective decimation ratios by arranging a plurality of sinc filters in different pipeline arrangements to produce the desired ratio. Power savings area achieved by implementing the sinc filters as FIR sinc filters and by implementing multiplications using look up tables.
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Angel Edwin De
Chow Chung-Kai
Lee Wai Laing
Page Joel
Wang Lei
Cirrus Logic Inc.
Mai Tan V.
Musgrove Jack V.
Skjerven Morrill & MacPherson LLP
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