Claims
- 1. A method of remotely locating buried compliant objects comprising the steps of:
- producing a probe signal having at least two frequencies;
- varying one of the at least two frequencies over a predetermined frequency range;
- emitting the probe signal from one or more sources;
- creating a vibration signal by vibrating a compliant object against a surrounding medium by the probe signal to cause a nonlinear vibration signal having difference frequencies equal to the difference between the varied frequency and the other frequency;
- receiving the nonlinear vibration signal having difference frequencies which is generated only when the probe signal impacts the compliant object; and
- comparing the amplitudes of the nonlinear vibration signal with predetermined amplitudes to indicate the presence of the compliant object.
- 2. The method of claim 1 further comprising the step of comparing an amplitude of the vibration signal with a pre-determined signal level.
- 3. The method of claim 1 further comprising varying both of the two frequencies over a predetermined frequency range.
- 4. The method of claim 1 further comprising the step of observing a nonlinear frequency response of the vibration signal for indicating the presence of the compliant object.
- 5. The method of claim 1 further comprising the step of observing the nonlinear vibration signal for identifying objects.
- 6. A method of remotely locating buried compliant objects comprising the steps of:
- producing a probe signal having at least first and second frequencies;
- emitting the probe signal from a source;
- creating a vibration signal by vibrating a compliant object against a surrounding medium by the probe signal to cause a nonlinear vibration signal having a third frequency;
- receiving the vibration signal caused by bouncing the probe signal on the boundaries of the compliant object against a surrounding medium wherein the vibration signal is only generated when the probe signal impacts the compliant object; and
- processing the nonlinear vibration signal.
- 7. The method of claim 6 further comprising the step of comparing an amplitude of the vibration signal with a pre-determined signal level.
- 8. The method of claim 6 wherein the third frequency is a different frequency from the first and second frequencies.
- 9. The apparatus of claim 6 wherein the third frequency comprises the difference between the first and second frequencies of the probe signal.
RELATED APPLICATIONS
This application is a continuation application of U.S. patent application Ser. No. 08/895,122 filed Jul. 16, 1997 by Donskoy, et al., now U.S. Pat. No. 5,974,881 dated Nov. 2, 199.
US Referenced Citations (16)
Non-Patent Literature Citations (2)
Entry |
Gros, et al., "Sensor Technologies for the Detection of Antipersonnel Mines A Survey of Current Research and System Developments," International Symposium on Measurement and Control Robotics (ISMCR'96), Brussels, May 9-11, 1996. |
Don, et al., "Using Acoustic Impulses to Identify a Buried Nonmetallic Object," J. Acoust. Soc. Am., vol. 95, No. 5, Pt. 2, May, 1994, pp. 2837-2838. |
Continuations (1)
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Number |
Date |
Country |
Parent |
895122 |
Jul 1997 |
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