System and method for monitoring wildlife

• US 5,452,364 A
• Filed: 12/07/1993
• Issued: 09/19/1995
• Est. Priority Date: 12/07/1993
• Status: Expired due to Fees

• Current Assignee: Douglas M. Bonham
• Original Assignee: Douglas M. Bonham
• Inventors: Bonham, Douglas M.
• Primary Examiner(s): BRINICH, STEPHEN M
• Application Number:
  US08/163,847
• Time in Patent Office: 651 Days
• Field of Search: 381/92, 381/155, 381/160, 367/125
• US Class Current: 381/92
• CPC Class Codes: A01M 31/002 Detecting animals in a given area
• CPC Class Codes: G01V 1/001 Acoustic presence detection

Abstract

A system and method for conducting surveys of vocalizing wildlife by determining the direction species of wildlife that emit vocalizations is disclosed. The system includes a sound receiving unit (12) with a set of three microphones (14, 16, 18) for monitoring the vocalizations. The signals received by the microphones are supplied to an audio signal processing circuit (20) that produces a set of subtractive signals indicating the relative signal strength of the received signals and a digital signal representative of the period of the received vocalizations. The signals produced by the audio signal processing circuit are supplied to a central processing unit (22). The central processing unit calculates the frequency of the vocalization based digital signal representative of the period of the signal and based on a set of these signals determines the species that emitted the vocalizations. A angular detection circuit integral with the audio signal processing circuit determines the angular direction relative to the sound receiving unit of from where the vocalization originated based on the subtractive signals.

Claims

1. A system for monitoring the location of a wildlife target that vocalizes, the vocalizations of the target being within a selected range of frequencies, said system comprising:

a sound receiving unit for receiving the vocalizations from the target, said sound receiving unit including a parabolic reflector having a focal point, a center microphone mounted to said parabolic reflector and located at said reflector focal point, a first offset microphone mounted to said parabolic reflector, and a second offset microphone mounted to said parabolic reflector, said first and second offset microphones being mounted to said parabolic reflector at diametrically opposite positions relative to said center microphone;

an audio signal processing circuit connected to said center microphone and said first and second offset microphones including a first subtractive signal representative of the difference in signal strength between the vocalizations monitored by said center microphone and said first offset microphone, a second subtractive circuit that produces a second subtractive signal representative of the difference in signal strength between the vocalizations monitored by said center microphone and said second offset microphone, and a vocalization signal based on the period of the vocalizations monitored by said center microphone;

an angular detection circuit connected to said audio signal processing circuit for receiving said subtractive signals that, in response to receiving said subtractive signals, generates an angular direction signal representative of the directions from which the received vocalizations originated relative to said sound receiving unit; and

a central processing unit connected to said audio signal processing circuit for receiving said vocalization signals and to said angular detection circuit for receiving said angular direction signal, said central processing unit, in response to receiving said vocalization signals and said angular direction signal determines the frequencies of the vocalization, and generating a frequency profile of the vocalization emitted by the target, said frequency profile including an indication of the angular direction relative to said sound receiving unit from which the vocalization was received.

2. The wildlife monitoring system of claim 1, wherein said audio signal processing unit includes at least one bandpass filter for filtering said sound signals monitored by said microphones, said bandpass filter being configured to selectively pass audio signals within a first range of frequencies of the vocalizations being monitored.

3. The wildlife monitoring system of claim 1, wherein said angular direction circuit includes a look-up table with a plurality of addressable memory locations, each said addressable memory location containing an angular direction value, and said angular direction circuit applies each pair of said first and second subtractive signals to said look-up table as memory address and retrieves said angular direction value stored at said memory address to function as said angular direction signal.

4. The wildlife monitoring system of claim 1, wherein said angular direction circuit includes:

a first look-up table with a plurality of addressable memory locations, said addressable memory locations in said first look-up table containing an initial angular direction values, and a second look-up table with a plurality of addressable memory locations, said addressable memory locations in said second look-up table containing adjusted angular direction values; and

said angular direction circuit applies each pair of said first and second subtractive signals to said look-up table-as a first memory address and retrieves said angular direction value stored at said first memory address to function as an initial angular direction signal, and said angular direction circuit applies each said initial angular direction signal and said vocalization signal to said second look-up table as a second memory address and retrieves said adjusted angular direction value stored at said second memory address to function as said angular direction signal.

5. The wildlife monitoring system of claim 4 wherein said angular detection circuit is integral with said audio signal processing circuit.

6. The wildlife monitoring system of claim 1 further including a phase comparitor integral with said audio signal processing circuit for monitoring the relative phases of said first and second subtractive signals, said phase comparator generating an out-of-signal as said vocalization signal when said subtractive signals are substantially out-of-phase;

and, wherein

said central processing unit, upon receiving said out-of-phase signal as said vocalization signal discards said angular direction signal received with said vocalization signal.

7. The wildlife monitoring system of claim 4 further including a phase comparitor integral with said audio signal processing circuit for monitoring the relative phases of said first and second subtractive signals, said phase comparator generating an out-of-signal as said vocalization signals when said subtractive signals are substantially out-of-phase;

and, wherein

said central processing unit, upon receiving said out-of-phase signal as said vocalization signal discards said vocalization signal and said angular direction signal received with said vocalization signal.

8. The wildlife monitoring system of claim 2 wherein said central processing unit includes at least one template of a frequency profile for a species of interest and said central processing unit compares said vocalization signal of the target vocalizations received by said sound receiving unit to determine if the vocalizations are within the frequency profile of the species of interest, and, if the vocalizations are within the frequency profile of the species of interest, said central processing unit uses said vocalization signals to produce said frequency profile of the vocalizations.

9. The wildlife monitoring system of claim 1, wherein said central processing unit includes at least one template of a frequency profile for a species of interest and, said central processing unit compares said vocalization signal to said template to determine if the received target vocalization are from the species of interest.

10. The wildlife monitoring system of claim 4, wherein said central processing unit includes at least one template of a frequency profile for a species of interest and, said central processing unit compares said vocalization signal to said template to determine if the received target vocalizations are from the species of interest.

11. The wildlife monitoring system of claim 1, wherein:

said sound receiving unit includes at least five linearly aligned microphones one of said microphones being said center microphone located at the reflector focal point, the remaining said microphones being diametrically positioned on opposite sides of said center microphone;

said audio signal processing circuit includes at least four subtractor circuits connected to said microphones for producing a plurality of subtractive signals, each said subtractive signal being representative of the difference in signal strength between the vocalizations monitored by two adjacent said microphones; and

said angular detection circuit is connected to said audio signal processing circuit for receiving said subtractive signals, said angular detection circuit being configured to produce said angular direction signal based on said subtractive signals.

12. A system for monitoring a given geographic area for a wildlife target from a species that vocalizes, the vocalizations of the species occurring within a specific range of frequencies and having a specific frequency profile, said system comprising:

at least two sound receiving units for receiving vocalizations from the target, each said sound receiving unit including a parabolic reflector having a focal point, a center microphone mounted to said parabolic reflector and located at said reflector focal point, a first offset microphone mounted to said parabolic reflector, and a second offset microphone mounted to said parabolic reflector, said first and second offset microphones being mounted to said parabolic reflector at diametrically opposite positions relative to said center microphone;

an audio signal processing circuit, each said audio signal processing circuit being connected to said center microphone and said first and second offset microphones for producing for each sound receiving unit a first subtractive signal representative of the difference in signal strength between the vocalizations monitored by said center microphone and said first offset microphone, a second subtractive signal representative of the difference in signal strength between the vocalizations monitored by said center microphone and said second offset microphone, and a vocalization signal based on the period of the vocalizations monitored by said center microphone;

an angular detection circuit connected to each said audio signal processing circuit for receiving said subtractive signals that, in response to receiving said subtractive signals, generates an angular direction signal for each said sound reflector representative of the directions from which the received vocalizations originated relative to said sound receiving unit; and

a central processing unit connected to said audio processing circuits for receiving said vocalization signals and to said angular detection circuit for receiving said angular direction signals, said central processing unit upon receiving said angular direction signals for said at least two sound receiving units determines the geographic location from which the vocalization originated.

13. The wildlife monitoring system of claim 12, wherein said central processing unit determines a frequency profile for said vocalization signals received by said at least two sound receiving units and if said processor unit determines said vocalization frequency profiles for substantially identical, said central processing unit proceeds to determine the geographic location from which the vocalization signals originated.

14. The wildlife monitoring system of claim 12, wherein:

each said sound receiving unit further includes a third offset microphone attached to said reflector and located between said center microphone and said reflector outer edge and a fourth offset microphone attached to said reflector between said center microphone and said reflector outer edge, said third and fourth offset microphones being located on opposite sides of said center microphone and linearly aligned with each other and said center microphone so as to be linearly offset with the alignment of said first and second offset microphones;

each said audio signal processing circuit is further connected to said third and fourth offset microphones of said sound receiving unit with which said processing circuit is associated and each said processing circuit further includes a third subtractor circuit for producing a third subtractive signal connected to said third offset microphone and said center microphone for producing a third subtractive signal representative of the difference in received signal strength between said center microphone and said third offset microphone and said center microphone and a fourth subtractor circuit for producing a fourth subtractive signal representative of the difference in received signal strength between said fourth microphone and said center microphone;

each said angular detection circuit receives is connected to said audio signal processing circuit associated therewith for receiving said first, second, third, and fourth subtractive signals, and in response to receiving said subtractive signals generates a vector indicating the vertical and horizontal directions from which the vocalization monitored by said sound record units originate; and

said central processing unit receives said vectors from said angular detection circuits and, determines the geographic origin of the vocalization based on said vectors.

15. The wildlife monitoring system of claim 14, wherein said central processing unit accepts said calculated geographic origin of said vocalizations as a true indication of the geographic origin of the vocalization if said calculated geographic origin is within a specific distance of said vectors from which said calculated geographic origin is determined.

16. A method of monitoring wildlife to determine the species and location of a wildlife target in a study area by listening to the vocalization produced by the target, including the steps of:

monitoring the vocalization produced by the target with a sound receiving unit, said sound receiving unit including a parabolic reflector having a focal point, a center microphone mounted to said parabolic reflector and located at said reflector focal point, a first offset microphone mounted to said parabolic reflector, and a second offset microphone mounted to said parabolic reflector, said first and second offset microphones being mounted to said parabolic reflector at diametrically opposite positions relative to said center microphone;

generating a first subtractive signal representative of a difference in received vocalization signal strength between said first offset microphone and said center microphone and generating a second subtractive signal representative of a difference in received signal strength between said second offset microphone and said second offset microphone and said center microphone;

determining the angular direction from which the vocalization was emitted relative to said sound receiving unit by reference to the relative magnitudes of said first and second subtractive signals;

generating a frequency profile of the vocalization monitored by said sound receiving unit; and

comparing said generated frequency profile of the received vocalization to a preestablished vocalization frequency profile of the target species and generating an indication of the species presence when the received target vocalization substantially matches said preestablished vocalization profile, said species presence indication including an indication of the angular direction of the target relative to said sound receiving unit when it emitted the vocalization.

17. The method of wildlife monitoring of claim 16 further including the steps of:

determining the phase relationship between said first and second subtractive signals; and

calculating said angular direction from which the vocalization originated when said first and second subtractive signals have a specific phase relationship.

18. The method of wildlife monitoring of claim 16, wherein said step of determining the angular direction form which the vocalizations originated includes the steps of:

converting said subtractive signals into a specific memory address; and

retrieving from an addressable memory unit an indication of the angular direction from which said vocalizations originated, said addressable memory unit containing a plurality of addressable memory locations, each said memory location containing an angular direction value, said retrieving step including the step of using said subtractive signals-based specific memory address as the address in said memory unit from which said angular direction value is retrieved.

19. The method of wildlife monitoring of claim 16, further including the step of determining the angular direction of from where the target vocalization originated based on the frequency of the vocalization.

20. The method of wildlife monitoring of claim 19, wherein said step of determining the angular direction from which the vocalizations originated includes the steps of:

converting said subtractive signals into a first memory unit address;

retrieving from an first addressable memory unit an initial indication of the angular direction from which said vocalizations originated, said first addressable memory unit containing a plurality of addressable memory locations, each said memory location containing an initial angular direction value, said retrieving step including the step of using said subtractive signals-based specific memory address as the address in said memory unit from which the initial angular direction value is retrieved;

generating a vocalization signal representative of the frequency of the received target vocalization;

combining said vocalization signal and said initial angular direction signals to produce a second memory unit address;

retrieving from a second addressable memory unit the indication of the angular direction from which said vocalizations originated, said second addressable memory unit containing a plurality of addressable memory locations, each said memory location containing an adjusted angular direction value, said retrieving step including the step of using said second memory unit address as the address in said memory unit from which the angular direction value is retrieved.

21. The method of wildlife monitoring of claim 20, further including the steps of:

determining the phase relationship between said first and second subtractive signals; and

calculating said angular direction from which the vocalization originated when said first and second subtractive signals have a specific phase relationship.