Echo ranging system for detecting velocity and range of targets using composite doppler invariant-like transmissions with suppression of false targets
US5212490A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 13, 1992 |
| Grant date | May 18, 1993 |
| Priority date | — |
| Expiry date | Mar 13, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/34
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
False target (reverberation, clutter, etc.) detection is suppressed in an echo ranging system (sonar or radar) in which target velocity and range are measured using a composite Doppler invariant-like signal having at least two segments, such as are present in a "rooftop" or "vee" HFM signal, such composite signal having an ambiguity function with two or more ridge lines of different slopes that intersect along the zero-velocity time axis. A bank of matched filters provides a distribution of outputs which has an ambiguity function-like character with intersecting pairs of ridge lines, the intersecting points of said pairs characterizing the range and velocity of the echo returns. This distribution is adjusted so that the intersecting ridge lines of each pair have equal and opposite slopes with respect to the time axis. In particular, fixed reverberators, which would have ridge lines intersecting on the zero-velocity time axis, would be symmetrical about this axis. A target with velocity v would present ridge lines intersecting along the v-velocity time axis and be symmetrical about that axis. Thus, the reverberation and the moving target would each have crossed ridge lines whose cha…
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