RECONSTRUCTION OF REFLECTING SURFACE VELOCITY AND DISPLACEMENT FROM DOPPLER SIGNALS

• US 3,663,932 A
• Filed: 07/15/1970
• Issued: 05/16/1972
• Est. Priority Date: 07/15/1970
• Status: Expired due to Term

• Current Assignee: Kontron (S&T AG)
• Original Assignee: Bruce Elson Mount, Harold Lee Massie
• Inventors: Massie, Harold Lee, Mount, Bruce Elson
• Primary Examiner(s): Farley, Richard A.
• Application Number:
  US05/054,983
• Time in Patent Office: 671 Days
• Field of Search: 340/1R,3D 343/9,8 356/28 73/194A
• US Class Current: 367/90
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements

Abstract

A method and apparatus for accurate measurement of velocity and displacement of a moving surface by reconstructing the velocityversus-time and displacement-versus-time functions comprising the steps of detecting the AM and FM or phase information of a Doppler echo signal from the surface to be measured, dividing the FM information by the AM information to obtain the velocity function, and, then, if desirable, performing an integrating step to obtain the relative displacement function.

Claims

1. A method for processing a Doppler signal resulting from a frequency shift of a carrier signal by reflection from a moving surface comprising, generating and transmitting the carrier signal, detecting the FM information and the AM information contained in said Doppler signal, and performing a division of the detected FM information by the detected AM information to provide an output signal representative of the surface velocity.

2. A method according to claim 1 including, integrating the output of said division step to provide an output signal representative of the relative surface displacement.

3. A method according to claim 1 wherein said detecting the AM information includes synchronously demodulating said Doppler signal with said carrier signal, and said detecting the FM information includes synchronously demodulating said Doppler signal with the carrier signal phase shifted to provide an AM signal, and then differentiating said AM signal.

4. A method according to claim 1 wherein said detecting the AM information includes synchronously demodulating said Doppler signal with said carrier signal at a first phase shift value and said detecting the FM information includes synchronously demodulating said Doppler signal with the carrier signal at a second phase shift value, and then differentiating said AM signal, whereby the difference between said first and second phase shift values amounts to pi /2.

5. An apparatus for processing a Doppler signal resulting from a frequency shift of a carrier signal by reflection from a moving surface, comprising means for generating and transmitting the carrier signal, means for detecting the FM and AM information contained in said Doppler signal, means coupled with said detecting means for performing a division of said FM information by said AM information to provide an output signal representative of velocity of said surface.

6. Apparatus according to claim 5 including means for integrating said output velocity signal to provide an output signal representative of relative displacement of said surface.

7. An apparatus according to claim 5 wherein said detecting means includes means for receiving said Doppler signal, first demodulating means coupled with said receiving means and said generating means for synchronously demodulating said Doppler signal to provide an AM information output, phase shift means connected from said generating means, second demodulating means coupled with said receiving means and said phase shift means for synchronously demodulating said Doppler signal, and differentiating means connected from said second demodulating means to provide an FM information output.

8. An apparatus according to claim 7 wherein said detecting means further includes, inhibiting means coupled from said first demodulating means for excluding zero crossing data from said AM information output to avoid division by zero.

9. An apparatus according to claim 8 including zero baseline establishing means connected from said first demodulating means and to said inhibiting means.

10. An apparatus according to claim 8 wherein said inhibiting means includes analog gate means connected between said first demodulating means and said division means, and comparator means connected from said first demodulating means and to said analog gate means to change original polarity indications of said AM information output for uniformity in application to said division means.

11. An apparatus according to claim 10 including restoring means connected from the output of said division means and said comparator means for restoring the original polarity indications.

12. An apparatus according to claim 11 including filter means coupled with saId restoring means for smoothing out the interruptions caused by said inhibiting means.

13. An apparatus according to claim 12 including integrating means coupled from said filter means to provide an output signal representative of relative displacement of the surface.

14. An apparatus according to claim 5 wherein said transmitting means includes means for generating said carrier signal in the form of ultrasonic energy.

15. An apparatus according to claim 5 where said division means includes an analog divider.

16. An apparatus according to claim 10 where said division means includes an analog divider.