Sonar depth sounder apparatus

• US 4,873,676 A
• Filed: 07/28/1987
• Issued: 10/10/1989
• Est. Priority Date: 06/14/1985
• Status: Expired due to Term

• Current Assignee: Johnson Outdoors, Inc.
• Original Assignee: Techsonic Industries, Inc. (Johnson Outdoors, Inc.)
• Inventors: Gibson, Robert R., Utz, Q. Wayne, Nunley, Alvin III, Bailey, James B.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Pihulic, Daniel T.
• Application Number:
  US07/078,871
• Time in Patent Office: 805 Days
• Field of Search: 367/97, 367/98, 367/900, 367/910, 367/112, 367/111, 73/290 V, 340/621, 181/124
• US Class Current: 367/98
• CPC Class Codes: G01S 15/08 Systems for measuring distance only indirect measurement G01S15/46
• CPC Class Codes: G01S 7/529 Gain of receiver varied automatically during pulse-recurrence period for seismic signals G01V1/245
• CPC Class Codes: G01S 7/53 Means for transforming coordinates or for evaluating data, e.g. using computers
• CPC Class Codes: G01S 7/56 Display arrangements short-range imaging G01S7/52053
• CPC Class Codes: Y10S 367/90 Sonar time varied gain control systems

Abstract

An improved microprocessor-controlled sonar depth sounder, which is automatically operative to detect and lock to the bottom of a body of water, fill in the display below the detected bottom, change display scales in response to the detected bottom going off-scale, and reformat the entire display in response to a scale change. A memory is provided for storing target data up to the operable depth limits of the device, thereby allowing display reversing and display expansion or "zoom" of a predetermined portion of the display selected by a zoom cursor. The zoom or cursor is variably positionable at different depths. The device employs an improved variable sensitivity amplifier. Also disclosed is an improved water-resistant switch construction for marine electronic equipment.

Claims

1. An improved variable sensitivity sonar receiver for use in an echo ranging depth sounder, comprising:

fixed gain amplifier means responsive to amplify an input signal at a predetermined gain to provide an amplified output signal, said amplifier means comprising a pair of cascaded amplifier stages, each of said amplifier stages operative to amplify an input signal at a predetermined gain,

one of said amplifier stages being operative to amplify the output signal provided by the other one of said amplifier stages to provide a high gain output signal and other one of said amplifier stages being operative to amplify said input signal to provide a low gain output signal;

comparator means for providing a comparator output signal when said amplified output signal exceeds a threshold signal, said comparator means comprising a first comparator and a second comparator,

said first comparator being operative to receive said high gain output signal and said second comparator being operative to receive said low gain output signal, each of said comparators providing said comparator output signal when the magnitude of its respective amplifier output signal exceeds the magnitude of said threshold signal;

means responsive to said comparator output signal for providing a target detection signal; and

means responsive to said target detection signal for varying said threshold signal as a function of a number of said target detection signals received.

2. An improved variable sensitivity sonar receiver for use in an echo ranging depth sounder, comprising:

fixed gain amplifier means responsive to amplify an input signal at a predetermined gain to provide an amplifier output signal;

comparator means for providing a comparator output signal when said amplified output signal exceeds a threshold signal;

means responsive to said comparator output signal for providing a target detection signal; and

means responsive to said target detection signal for varying said threshold signal as a function of a number of said target detection signals received, said threshold varying means comprising logarithmic signal generating means,

whereby said threshold signal is varied as a logarithmic function of said number of said target detection signals received.

3. In an echo ranging depth sounder, a method for detecting and locking the depth sounder to the bottom of as body of water, comprising the steps of:

finding a widest sonar target within the operative depth limits of the depth sounder;

incrementing a bottom count every time said widest target is found;

comparing said bottom count to a predetermined number;

when said bottom count reaches said predetermined number, setting a bottom flag to indicate that said bottom of said body of water has been detected;

determining the depth of the shallowest portion of said widest target in response to said bottom flag; and

providing the depth of said shallowest portion as the depth of said bottom of said body of water.

4. The method of claim 3, further comprising the step of filling in a visual display of the depth sounder below said depth of said detected bottom.

5. The method of claim 3, further comprising the steps of:

incrementing a lost count every time a target having a width at least as wide as said widest target of a previous sonar return is not found in response to a sonar transmission subsequent to setting said bottom flag;

comparing said lost count to a second predetermine number;

when said lost count reaches said second predetermined number, clearing said bottom flag to indicate that the bottom has been lost.

6. The method of claim 3, wherein said depth sounder includes a visual display, and further comprising the step of:

automatically selecting one of a plurality of depth scales for said display in response to said depth of said detected bottom, whereby a rising bottom depth selects a shallower depth scale and a falling bottom depth selects a deeper depth scale.

7. The method of claim 3, wherein the step of finding said widest sonar target comprises the step of identifying a particular target having the greatest depth range of a plurality of targets.

8. The method of claim 3, wherein the step of find said wide sonar target comprises the finding said widest sonar target from signals received by the depth sounder resulting from a plurality of sonar pulses transmitted by the depth sounder.

9. In an echo ranging depth sounder, apparatus for automatically adjusting a selectively setting of a sonar receiver, comprising:

means for receiving target data corresponding to sound reflections resulting from a sound pulse transmitted by said depth sounder, said receiving means including a selectively variable gain or sensitivity setting;

means responsive to said target data for distinguishing the bottom of a body of water from other targets and providing a bottom depth signal, said bottom distinguishing means comprising means for finding a widest sonar target within the operative depth limits of the depth sounder,

counter means for counting said widest sonar targets found by said finding means in a plurality of consecutive sonar returns and for providing a bottom count,

means for comparing said bottom count to a predetermined number,

means for providing a bottom flag to indicate that said bottom has been detected when said bottom count equals said predetermined number,

means for determining the depth of the shallowest portion of the sonar return corresponding to said widest target in response to said bottom flag, and

means for providing said depth of said shallowest sonar return as said bottom depth signal; and

means responsive to said bottom depth signal for adjusting said gain or sensitivity setting for said receiving means.

10. In an echo ranging depth sounder, apparatus for automatically adjusting a selectively variable gain or sensitivity setting of a sonar receiver, comprising:

means for receiving target data corresponding to sound reflections resulting from a sound pulse transmitted by said depth sounder, said receiving means including a selectively variable gain or sensitivity setting, said receiving means comprising amplifier means responsive to amplify an input signal to said receiver at a predetermined gain to provide an amplified output signal, comparator means for providing a comparator output signal when said amplified output signal exceeds a threshold signal, and means responsive to said comparator output signal for providing a target detection signal when said comparator output signal exceeds a predetermined magnitude;

means responsive to said target data for distinguishing the bottom of a body of water from other targets and for providing a bottom depth signal; and

means responsive to said bottom depth signal for adjusting said gain or sensitivity setting for said receiving means, said gain or sensitivity adjusting means comprising means responsive to said bottom depth signal for varying said threshold signal as a function of said bottom depth.

11. In an echo ranging depth sounder, a method for automatically adjusting a selectively variable gain or sensitivity setting of a sonar receiver, comprising the steps of:

determining a sum of a number of sonar signal target returns received in response to a predetermined number of sonar transmissions;

comparing said sum to a predetermined upper limit;

if said sum exceeds said upper limit, incrementing a counter;

comparing said sum to a predetermined lower limit;

if said sum is less than said lower limit, decrementing said counter;

comparing the contents of said counter to a count upper limit;

decreasing a gain or sensitivity of the depth sounder in response to the contents of said counter exceeding said counter upper limit;

then resetting said counter to a first initial value;

comparing the contents of said counter to a count lower limit;

increasing said gain or sensitivity setting of the depth sounder in response to the contents of said counter being less than said count lower limit, then resetting said counter a second initial value,

whereby the gain or sensitivity is increased or decreased as a function of the number of sonar signal returns received.

12. The method of claim 11, wherein the step of determining said sum of a number of sonar signal target returns comprises determining a number of sonar signal target returns within a predetermined depth range received in response to a predetermined number of sonar transmissions.

13. The method of claim 11, wherein said first initial value equals said second initial value, and wherein said initial value comprise an average of said counter upper limit and said count lower limit.

14. In an echo ranging depth sounder including means for displaying information corresponding to target sonar returns, apparatus for detecting a bottom of a body of water, comprising the steps of:

bottom finding means for finding a widest sonar target within the operative depth limits of the depth sounder;

counter means for counting said widest sonar targets found by said bottom finding means in a plurality of consecutive sonar returns and for providing a bottom count;

means for comparing said bottom count to a predetermined number;

means for providing a bottom flag to indicate that said bottom has been detected when said bottom count equals said predetermined number;

means for determining the depth of the shallowest portion of the sonar return corresponding to said widest target in response to said bottom flag; and

means for providing said depth of said shallowest sonar return as the depth of said detected bottom.

15. The apparatus of claim 14, wherein said depth sounder includes a visual display, and further comprising means for filling in said display below said depth of said detected bottom.

16. The apparatus of claim 14, further comprising:

lost bottom counter means for maintaining a lost bottom count of each time said bottom finding means fails to find a target subsequent to setting said bottom flag;

means for comparing said lost bottom count to a second predetermined number;

means for clearing said bottom flag to indicate that said bottom has been lost when said lost bottom count equals said second predetermined number.

17. The apparatus of claim 14, wherein said depth sounder includes a visual display and further comprising:

means for automatically selecting one of a plurality of depth scales for said display in response to said depth of said detected bottom, whereby a rising bottom depth selects a shallower depth scale and a falling bottom depth scale selects a deeper depth scale.

18. In an echo ranging depth sounder, an apparatus for automatically adjusting a selectively variable gain or sensitivity setting of a sonar receiver, comprising:

means for obtaining a number of sonar signal target returns received in response to a predetermined number of sonar transmissions;

means for comparing said number to a predetermined upper limit;

counter means responsive to increment in response to said number equaling said upper limit;

means for comparing said number to a predetermined lower limit;

said counter being responsive to decrement in response to said number equaling said lower limit;

means for comparing a count maintained by said counter to a count upper limit;

means for decreasing a gain or sensitivity setting of the depth sounder in response to said counter exceeding said count upper limit and resetting said counter to an initial value;

means for comparing said count maintained by said counter to a count lower limit; and

means for increasing said gain or sensitivity setting of the depth sounder in response to said counter being less than said count lower limit and resetting said counter lower limit and resetting said counter to said initial value,

whereby the gain or sensitivity is increased or decreased as a function of the number of sonar signal returns received.

19. In an apparatus for displaying information in an echo ranging depth sounder including sonar pulse generating means and transducer means responsive to reflected sonar pulses for acquiring target data representative of reflected sonar pulses, an improved information display, comprising:

display means for displaying target data in a format corresponding to a predetermined depth scale, said display means including depth indicia corresponding to said predetermined depth scale;

means for generating an alarm cursor on said display means which is selectively positionable with respect to said predetermined depth scale, said alarm cursor corresponding to a selectively variable alarm depth relative to said predetermined depth scale;

alarm means responsive to provide an alarm signal upon detection of target data within said selectively variable alarm depth; and

means responsive to said alarm signal for communicating said alarm signal to an operator.

20. The improved information display of claim 19, wherein said predetermined depth scale is a first predetermined depth scale and said format for display of said target data is a first format, and further comprising:

means for displaying said target data on said display means in a second format corresponding to a second predetermined depth scale;

scale selecting means for alternatively selecting said first depth scale or said second depth scale; and

alarm cursor reformatting means responsive to reformat said alarm cursor on said display to relate said alarm cursor to said second predetermined depth scale when said second depth scale is selected.

21. An improved variable sensitivity sonar receiver for use in an echo ranging depth sounder, comprising:

a pair of cascaded fixed gain amplifier stages comprising a first amplifier stage and a second amplifier stage, said first amplifier stage being operative to amplify an input signal at a predetermined first gain to provide a first amplifier output signal, said second amplifier output signal, said second amplifier stage being operative to amplifier output signal;

a first comparator responsive to said first amplifier output signal for providing a first comparator output signal when said first amplifier output signal exceeds a first threshold signal;

a second comparator responsive to said second amplifier output signal for providing a second comparator output signal when said second amplifier output signal exceeds a second threshold signal;

threshold generating means for providing said first threshold signal and said second threshold signal;

means for varying said first threshold signal and said second threshold signal; and

means responsive to said first and said second comparator output signals for providing a target detection signal.

22. The variable sensitivity sonar receiver of claim 21, wherein said predetermined first gain and said predetermined second gain are both about 30 dB.

23. The variable sensitivity sonar receiver of claim 21, wherein said first threshold signal and said second threshold signal comprise a single threshold signal.

24. The variable sensitivity sonar receiver of claim 21, further comprising means for detecting a number of sonar signal returns being received which correspond to a bottom of a body of water, and wherein said first threshold signal and said second threshold signal are provided as a function of said number of sonar signal returns.

25. In an apparatus for displaying information in an echo ranging depth sounder including sonar pulse generating means and transducer means responsive to reflected sonar pulses for acquiring target data representative of reflected sonar pulses, an improved information display, comprising:

display means for displaying target data in a first format corresponding to a first predetermined depth scale or alternatively in a second format corresponding to a second predetermined depth scale, said display means including depth indicia corresponding to a displayed one of said predetermined depth scales;

means for generating a selectively positionable alarm cursor on said display means, said alarm cursor relating to said displayed one of said predetermined depth scales, said alarm cursor corresponding to a selectively variable alarm depth relative to said displayed one of said predetermined depth scales;

alarm means responsive to provide an alarm signal upon detection of target data within said selectively variable alarm depth;

means responsive to said alarm signal for communicating said alarm signal to an operator;

scale selecting means for operator selection of said first format or said second format; and

alarm cursor reformatting means responsive to said scale selecting means for reforming said alarm cursor on said display means to relate said alarm cursor to said first depth scale when said first format is selected or to said second depth scale when said second format is selected.