Overflow threshold control for sonar
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsEdward A. Caporin, Joseph Abruzzo, Frank L. Rees
Life of this patent
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Abstract
1. In combination in a sonar system for displaying a succession of echo sals received from a target illuminated respectively by a succession of transmitted pulses, Means for generating a base threshold quantity related to background noise, A comparator for comparing the amplitude of each echo signal with the base threshold, First means responsive to received signals which pass said comparator for changing said base threshold in predetermined relatively small increments, Second means responsive to received signals which pass said comparator for changing said base threshold in predetermined relatively large increments.
Claims8
In combination in a sonar system for displaying a succession of echo signals received from a target illuminated respectively by a succession of transmitted pulses,
- means for generating a base threshold quantity related to background noise,
- a comparator for comparing the amplitude of each echo signal with the base threshold,
- first means responsive to received signals which pass said comparator for changing said base threshold in predetermined relatively small increments,
- second means responsive to received signals which pass said comparator for changing said base threshold in predetermined relatively large increments.
A system for displaying repetitive sonar signals received from a target comprising,
- means for generating a base threshold voltage commensurate with average noise voltage amplitude,
- means for comparing each received sonar signal with said threshold voltage,
- a short decay time register with logic circuitry coupled to said comparing means for accumulating digital counts at a relatively fast rate in response to each threshold-exceeded signal and dissipating said counts at a relatively fast rate in the absence of signals,
- a long decay time register with logic circuitry coupled to said comparing means for accumulating digital counts at a relatively slow rate in response to each threshold-exceeded signal and dissipating said counts at a relatively slow rate in the absence of signals, and
- means coupling said registers and said base threshold generating means for modifying the amplitude of said threshold voltage in response to frequency of occurrence of sonar signals.
In combination in a sonar system for successively sampling sonar beam signals received at a transducer array from a plurality of directions in response to each transmitted pulse, and buffer storage means for storing each threshold-exceeded signal at a different address in said buffer memory, said combination comprising,
- a comparator with two input circuits and one output circuit,
- a source of base threshold signal coupled to one of said inputs,
- a scanning switch means for successively applying said beam signals to the other of said input circuits,
- a short decay time integrator and a short decay time threshold correction register coupled to the output of said comparator,
- a long decay time counter and a long decay time threshold correction register coupled to the output of said comparator, and
- means for adding the short decay time correction and the long decay time correction to said base threshold signal.
Dependencies are inferred from the claim text.