Coupled nonlinear sensor system for sensing a time-dependent target signal and method of assembling the system

1. A coupled nonlinear sensor system for sensing a non-sinusoidal time-dependent target signal, comprising an odd number, other than one, of interconnected oscillatory sensors for sensing time-dependent changes in an external magnetic flux generated by the non-sinusoidal time-dependent target signal, said sensors coupled to each other by a coupling parameter characterized by a threshold value, so that each of said sensors oscillates in the presence of the non-sinusoidal time-dependent target signal as the coupling parameter exceeds the threshold value.

2. The system of claim 1 , further comprising a control unit coupled to said oscillatory sensors for controlling said oscillatory sensors.

3. The system of claim 2 , wherein said control unit is capable of storing a plurality of predetermined non-sinusoidal time-dependent target signals corresponding to respective ones of a plurality of predetermined objects.

4. A coupled nonlinear sensor system for sensing a non-sinusoidal time-dependent target signal having a frequency of oscillation, comprising an odd number, other than one, of interconnected oscillatory sensors oscillating in response to time-dependent changes in an external magnetic flux generated by the non-sinusoidal time-dependent target signal, said sensors coupled one to another by a coupling parameter having a predetermined threshold value, each of said sensors oscillating at a frequency responsive to presence of the non-sinusoidal time-dependent target signal as the coupling parameter exceeds the threshold value.

5. The system of claim 4 , wherein each of said sensors is capable of oscillating at a frequency synchronized to the frequency of oscillation of the non-sinusoidal time-dependent target signal, each of said sensors capable of only oscillating in presence of the non-sinusoidal time-dependent target signal for sensing the non-sinusoidal time-dependent target signal.

6. The system of claim 4 , wherein each of said sensors is capable of oscillating in absence of the non-sinusoidal time-dependent target signal at an amplitude modulatable by presence of the non-sinusoidal time-dependent target signal for sensing the non-sinusoidal time-dependent target signal.

7. The system of claim 4 , further comprising a control unit coupled to said oscillatory sensors for controlling said oscillatory sensors.

8. The system of claim 7 , wherein said control unit is capable of storing a plurality of predetermined non-sinusoidal time-dependent target signals corresponding to respective ones of a plurality of predetermined objects, so that the detected non-sinusoidal time-dependent target signal is capable of being compared to the stored non-sinusoidal time-dependent target signals for uniquely identifying the object generating the detected non-sinusoidal time-dependent target signal.

9. The system of claim 4 , wherein each of said sensors is a fluxgate magnetometer.

10. A coupled nonlinear sensor system for sensing a non-sinusoidal time-dependent target signal having a frequency of oscillation, comprising:

(a) at least three panels joined to define a triangularly-shaped frame in transverse cross-section:

(b) at least three interconnected fluxgate magnetometers mounted on respective ones of said panels and adjacent one to another, each of said fluxgate magnetometers including:

(i) a ferromagnetic core,

(ii) a driver coil wound about said core for exciting said core to generate a magnetic flux,

(iii) a sensor coil wound about said core and in sensing communication with the magnetic flux for sensing changes in the magnetic flux and for generating a sensor coil output signal in response to the changes in the magnetic flux, (iv) a first amplifier connected to said sensor coil for receiving and amplifying the sensor coil output signal to generate an amplifier output signal,

(v) a current-to-voltage converter connected to said amplifier for receiving the amplifier output signal and for converting an electrical current thereof to a voltage, so as to generate a first converter voltage output signal,

(vi) an integrator electrically connected to the current-to-voltage converter for receiving and integrating the first converter voltage output signal and generating an integrator output signal,

(vii) a filter connected to said integrator for receiving and filtering the integrator output signal to generate a filter output signal,

(viii) a second amplifier connected to said filter for receiving and amplifying the filter output signal to generate an amplified filter output signal,

(ix) voltage-to-current converter connected to said second amplifier for receiving the amplified filter output signal and for converting the voltage into a current to generate a voltage-to-current converter output signal, said voltage-to-current converter being connected to the driver coil belonging to an adjacent one of said fluxgate magnetometers, each of said magnetometers oscillating in response to time-dependent changes in an external magnetic flux generated by the non-sinusoidal time-dependent target signal, said sensors coupled one to another by a coupling parameter having a predetermined threshold value, each of said sensors oscillating at a frequency responsive to presence of the non-sinusoidal time-dependent target signal as the coupling parameter exceeds the threshold value; and

(c) a power supply coupled to said at least three fluxgate magnetometers for supplying power to said fluxgate magnetometers.

11. The system of claim 10 , further comprising a control unit coupled to said fluxgate magnetometers for controlling said fluxgate magnetometers.

12. The system of claim 11 , wherein said control unit is capable of storing a plurality of predefined non-sinusoidal time-dependent target signals corresponding to respective ones of a plurality of predetermined objects, so that the detected non-sinusoidal time-dependent target signal is capable of being compared to the stored non-sinusoidal time-dependent target signals for uniquely identifying the object generating the detected non-sinusoidal time-dependent target signal.

13. A method of assembling a coupled nonlinear sensor system for sensing a non-sinusoidal time-dependent target signal, comprising the step of interconnecting an odd number, other than one, of oscillatory sensors for sensing time-dependent changes in an external magnetic flux generated by the non-sinusoidal time-dependent target signal, the sensors coupled to each other by a coupling parameter having a threshold value, so that each of the sensors oscillates in presence of the non-sinusoidal time-dependent target signal as the coupling parameter exceeds the threshold value.

14. The method of claim 13 , wherein the step of interconnecting an odd number of oscillatory sensors comprises the step of interconnecting an odd number of oscillatory sensors so that the oscillatory sensors are self-oscillating.

15. The method of claim 13 , wherein the step of interconnecting an odd number of oscillatory sensors comprises the step of interconnecting an odd number of oscillatory sensors so that the oscillatory sensors are self-modulating.

16. The method of claim 13 , further comprising a step of coupling a control unit to the oscillatory sensors for controlling the oscillatory sensors.

17. The method of claim 13 , wherein the step of coupling a control unit comprises the step of coupling the control unit, so that the control unit is capable of storing a plurality of predetermined non-sinusoidal time-dependent target signals corresponding to respective ones of a plurality of predetermined objects.

18. A method of assembling a coupled nonlinear sensor system for sensing a non-sinusoidal time-dependent target signal having a frequency of oscillation, comprising the step of interconnecting an odd number, other than one, of oscillatory sensors oscillating in response to time-dependent changes in an external magnetic flux generated by the non-sinusoidal time-dependent target signal, the sensors coupled one to another by a coupling parameter having a predetermined threshold value, each of the sensors oscillating at a frequency responsive to presence of the non-sinusoidal time-dependent target signal as the coupling parameter exceeds the threshold value.

19. The method of claim 18 , wherein the step of interconnecting the sensors comprises the step of interconnecting the sensors so that each of the sensors is capable of oscillating at a frequency synchronized to the frequency of oscillation of the non-sinusoidal time-dependent target signal, and so that each of the sensors only oscillates in presence of the non-sinusoidal time-dependent target signal for sensing the non-sinusoidal time-dependent target signal.

20. The method of claim 18 , wherein the step of interconnecting the sensors comprises the step of interconnecting the sensors so that each of the sensors is capable of oscillating in absence of the non-sinusoidal time-dependent target signal at an amplitude modulatable by presence of the non-sinusoidal time-dependent target signal for sensing the non-sinusoidal time-dependent target signal.

21. The method of claim 18 , further comprising the step of coupling a control unit coupled to said oscillatory sensors for controlling said oscillatory sensors.

22. The method of claim 21 , wherein the step of coupling a control unit comprises the step of coupling the control unit, so that the control unit is capable of storing a plurality of predetermined non-sinusoidal time-dependent target signals corresponding to respective ones of a plurality of predetermined objects, so that the detected non-sinusoidal time-dependent target signal is capable of being compared to the stored non-sinusoidal time-dependent target signals for uniquely identifying the object generating the detected non-sinusoidal time-dependent target signal.

23. The method of claim 18 , wherein the step of interconnecting an odd number of oscillatory sensors comprises the step of interconnecting an odd number of fluxgate magnetometers.

24. A method of assembling a coupled nonlinear sensor system for sensing a non-sinusoidal time-dependent target signal having a frequency of oscillation, comprising the steps of:

(a) joining three panels to define a triangularly-shaped frame in transverse cross-section;

(b) mounting three interconnected fluxgate magnetometers on respective ones of the panels and adjacent one to another, the step of mounting the interconnected fluxgate magnetometers including the steps of:

(i) providing a ferromagnetic core,

(ii) winding a driver coil about the core for exciting the core to generate a magnetic flux,

(iii) winding a sensor coil about the core, the sensor coil capable of being in sensing communication with the magnetic flux for sensing changes in the magnetic flux and for generating a sensor coil output signal in response to changes in the magnetic flux,

(iv) connecting a first amplifier to the sensor coil for receiving and amplifying the sensor coil output signal to generate an amplifier output signal,

(v) connecting a current-to-voltage converter to the first amplifier for receiving the amplifier output signal and for converting an electrical current thereof to a voltage, so as to generate a first converter voltage output signal,

(vi) connecting an integrator to the current-to-voltage converter for receiving and integrating the first converter voltage output signal and generating an integrator output signal,

(vii) connecting a filter to the integrator for receiving and filtering the integrator output signal in order to generate a filter output signal,

(viii) connecting a second amplifier to the filter for receiving and amplifying the filter output signal to generate an amplified filter output signal,

(ix) connecting a voltage-to-current converter to the second amplifier for receiving the amplified filter output signal and for converting the voltage into a current to generate a voltage-to-current converter output signal, the voltage-to-current converter being connected to the driver coil belonging to an adjacent one of the fluxgate magnetometers, each of the magnetometers oscillating in response to time-dependent changes in an external magnetic flux generated by the non-sinusoidal time-dependent target signal, the sensors coupled one to another by a coupling parameter having a predetermined threshold value, each of the sensors oscillating at a frequency responsive to presence of the non-sinusoidal time-dependent target signal as the coupling parameter exceeds the threshold value; and

(c) coupling a power supply to the fluxgate magnetometer for supplying power to the fluxgate magnetometer.