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Underwater Signal Discrimination System.
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In: DTIC AND NTIS (1980)
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Abstract:
In an underwater-target detection apparatus of the echo-ranging type wherein a receiver signal, resulting from transmission of search pulses, comprises reverberation and at times a target echo, said reverberation presenting a frequency spectrum of greater bandwidth than said target echo and presenting an amplitude-modulaton envelope generally including pulses of character similar to said search pulses, and said target echo occurring at an unpredictable frequency within a comparatively wide frequency band substanially centered upon the reverberation mean frequency, a receiver circuit for effecting discrimination of target echoes from reverberation, said receiver cicuit comprising: first filter means having a rejection notch characteristic centered upon the reverberation mean frequency, and of comparatively limited bandwidth substantially matching that of the major energy portion of said reverberation, for converting said receiver signal to a modified signal with strong attenuation of reverberation in only a correspondingly limited central portion of its frequency spectrum and without substantially affecting target echoes occurring at frequencies outside of said rejection notch; demodulator means for deriving from said modified signal a unipolar signal corresponding to the modulaton envelope of said modified signal; and second filter means having a bandpass response characteristic with upper cutoff frequency substantially equal to half said limited bandwidth of the first filter means rejection notch, for isolating, from said unipolar signal, only such signal pulses as correspond to target echoes. (Author) ; Supersedes PAT-APPL-239 384-62.
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Keyword:
*Patents; *Sonar sound analyzers; *Underwater sound signals; Acoustic Detection and Detectors; Background noise; Broadband; Notch filters; PAT-CL-367-95; Reverberation; Signal to noise ratio; Target discrimination; Target echoes
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URL: http://www.dtic.mil/docs/citations/ADD007400
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADD007400
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| 62 |
Automated Intelligibility Measurement System.
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In: DTIC AND NTIS (1980)
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| 63 |
Acoustic Signals for Emergency Evacuation
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In: DTIC AND NTIS (1979)
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| 65 |
Stochastic Modeling as a Means of Automatic Speech Recognition
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In: DTIC AND NTIS (1975)
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| 66 |
Segmentation and Labeling of Speech: A Comparative Performance Evaluation
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In: DTIC AND NTIS (1975)
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| 67 |
Acoustic Alteration of Speech Processed Through Air Force Aircraft Communication Systems.
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In: DTIC AND NTIS (1974)
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| 69 |
The Role of Acoustic Processing in Speech Understanding Systems
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In: DTIC AND NTIS (1973)
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| 70 |
An Investigation of the Cross Correlation of Speech Signals
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In: DTIC AND NTIS (1970)
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| 71 |
Whale Phonations in Repetitive Stanzas.
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In: DTIC AND NTIS (1970)
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| 73 |
Acoustic Measurements for Speaker Recognition
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In: DTIC (1969)
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| 74 |
An Empirical Equation for the Determination of the Maximum Side-Aspect Target Strength of an Individual Fish
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In: DTIC AND NTIS (1969)
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| 75 |
ASPECTS OF SPEECH RECOGNITION BY COMPUTER.
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In: DTIC AND NTIS (1969)
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| 76 |
An Automatic Electronic Speech Teaching Responder.
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In: DTIC AND NTIS (1968)
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| 78 |
A STUDY OF CRITICAL-INSTANT SAMPLING OF SPEECH PARAMETERS FOR AUTOMATIC RECOGNITION OF SPOKEN WORDS.
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In: DTIC AND NTIS (1966)
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| 79 |
PHYSICAL AND PERCEPTUAL IDENTIFICATIONS OF CZECH VOWELS.
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In: DTIC AND NTIS (1966)
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| 80 |
ON COGNITION OF SPEECH SOUNDS WITH THE AID OF SELF-ORGANIZING SYSTEMS WITH TWO POSITIVE FEEDBACKS.
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In: DTIC AND NTIS (1966)
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