Patent ID: 6108269
Filing Date: 2000-08-22
Classification: G01S,Y10S

Abstract:
A sonar depth sounder device comprising:a display;a transmitter for generating a plurality of sonar signals toward the bottom surface of a body of water, wherein said transmitter transmits at least one sonar signal towards a bottom surface of said body of water;a receiver, wherein said receiver receives a reflected sonar signal corresponding to said transmitted signal; anda processor, connected to said transmitter and said receiver, wherein said receives sonar signals indicative of ambient noise in said body of water and sends a signal representative of said ambient noise to said processor;wherein said processor determines a detection threshold value based upon said signal representative of said ambient noise;wherein said processor causes said display to display data corresponding to said reflected sonar signal when said reflected sonar signal has an amplitude greater than said detection threshold; andwherein said processor calculates said detection threshold value (DT) according to the following equation:DT=mean.sub.ambient +.alpha.variance.sub.ambientwhere mean.sub.ambient is the mean of said sonar signal indicative of ambient noise, and where variance.sub.ambient is the variance of said sonar signal indicative of ambient noise, and where .alpha. is a scaling factor.