Detection and ranging systems and methods

Patent metadata

Field	Value
Publication number	US-10838040-B2
Application number	US-201815977095-A
Country	US
Kind code	B2
Filing date	May 11, 2018
Priority date	Nov 13, 2015
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

Techniques are disclosed for detection and ranging systems and methods to improve range resolution, target separation, and reliability. A method includes selectively attenuating a signal representing a ranging system return or echo from targets so as to suppress side lobes or other undesirable artifacts appearing in the signal due to noise, interference, and/or distortion. A method may additionally or alternatively include rejecting interference events in ranging system returns by comparing a received return with that expected from a target illuminated by the ranging system, as determined by characteristics of its particular ranging sensor, and rejecting or attenuating returns or portions of returns that fail to match those characteristics in time or space. A system configured to perform such methods and comprising a transducer/antenna, a transceiver, a controller, and/or other logic devices implementing a pulse generator, correlator, selective attenuator, comparator, buffer, subtractor, and/or output circuit is also disclosed.

First claim

What is claimed is:

1. A method comprising:
transmitting a pulse having a carrier wave toward a target;
receiving at least a portion of the pulse reflected from the target as a return signal;
determining a correlated return signal based on the return signal and the pulse;
comparing the correlated return signal against one or more bounds that are determined relative to the return signal;
attenuating portions of the correlated return signal that fall outside the one or more bounds; and
providing the correlated return signal with weakly correlated and/or distorted portions suppressed by the attenuating.

2. The method of claim 1 , wherein the one or more bounds comprise:
a lower bound determined based on the return signal scaled by a first weight; and
an upper bound determined based on the return signal scaled by a second weight.

3. The method of claim 2 , wherein the first and the second weights are determined based on the energy in the pulse.

4. The method of claim 3 , wherein the second weight is determined further based on sizes of targets to be detected.

5. The method of claim 1 , wherein the attenuating of the portions of the correlated return signal comprises scaling the portions of the correlated return signal by a third weight that is greater than or equal to zero and less than one.

6. The method of claim 5 , further comprising:
adjusting the third weight, and
detecting targets from peaks of the correlated return signal with weakly correlated and/or distorted portions suppressed by the attenuating.

7. The method of claim 1 , wherein the determining of the correlated return signal comprises determining a cross-correlation between the return signal and the pulse.

8. The method of claim 1 , wherein:
the transmitting of the pulse comprises modulating a frequency or a phase of the carrier wave within the pulse to perform pulse compression; and
the attenuating comprises suppressing side lobes in the correlated return signal due to the pulse compression.

9. The method of claim 1 , wherein:
the pulse is a radar pulse having a radio frequency (RF) wave as the carrier wave or a sonar pulse having an audio frequency (AF) wave as the carrier wave; and
the transmitting of the pulse comprises shaping an envelope of the pulse into a rectangular, triangular, trapezoidal, or Gaussian envelope.

10. The method of claim 1 , wherein the return signal comprises a first sensor return received from a ranging system, the method further comprising:
receiving a second sensor return from the ranging system;
determining a gradient of the first and/or second sensor return; and
attenuating the first and/or second sensor return based, at least in part, on the determined gradient and/or a gradient limit for the ranging system.

11. A system, comprising:
a transceiver/controller comprising:
a pulse generator configured to generate a pulse having a carrier wave;
a correlator configured to determine a correlated return signal based on a return signal and the pulse, the return signal representing at least a portion of the pulse reflected from a target;
a selective attenuator configured to compare the correlated return signal against one or more bounds that are determined relative to the return signal and attenuate portions of the correlated return signal that fall outside of the one or more bounds; and
an output configured to provide the correlated return signal as a target ranging signal with weakly correlated and/or distorted portions of the correlated return signal suppressed by the selective attenuator; and

a transducer or antenna coupled to the transceiver/controller and configured to transmit the pulse toward the target and receive the portion of the pulse reflected from the target.

12. The system of claim 11 , wherein the one or more bounds comprise:
a lower bound determined based on the return signal scaled by a first weight; and
an upper bound determined based on the return signal scaled by a second weight.

13. The system of claim 12 , wherein the first and the second weights are determined based on the energy in the pulse.

14. The system of claim 13 , wherein the second weight is determined further based on sizes of targets to be detected.

15. The system of claim 11 , wherein the selective attenuator is configured to attenuate the portions of the correlated return signal at least by scaling the portions of the correlated return signal by a third weight that is greater than or equal to zero and less than one.

16. The system of claim 11 , wherein:
the selective attenuator is configured to adjust the third weight, and
the transceiver/controller is configured to detect targets from peaks of the target ranging signal.

17. The system of claim 11 , wherein:
the correlator is configured to determine the correlated return signal at least by determining a cross-correlation between the return signal and the pulse; and
the correlator and the selective attenuator are implemented in a field programmable gate array (FPGA) or a digital signal processor (DSP).

18. The system of claim 11 , wherein
the pulse generator is configured to modulate a frequency or a phase of the carrier wave within the pulse to perform pulse compression; and
side lobes in the correlated return signal due to the pulse compression are suppressed by the selective attenuator.

19. The system of claim 11 , wherein the pulse generator is configured to shape an envelope of the pulse into a rectangular, triangular, trapezoidal, or Gaussian envelope, and wherein:
the carrier wave for the pulse is a radio frequency (RF) wave and the system comprises a radar; or
the carrier wave for the pulse is an audio frequency (AF) wave and the system comprises a sonar.

20. The system of claim 11 , wherein the return signal comprises a first sensor return received from the transducer or antenna, and wherein the transmitter/controller is configured to receive a second sensor return from the transducer or antenna, the system further comprising:
a subtractor configured to determine a gradient of the first and/or second sensor return; and
a selective attenuator configured to attenuate the first and/or second sensor return based, at least in part, on the determined gradient and/or a gradient limit for the system.

Assignees

• FLIR Belgium BVBA

Inventors

• Jales Richard
• St Hill Nicholas
• Tostevin Stephen

Classifications

• G01S7/023

  Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36) · CPC title

• G01S7/288

  Coherent receivers · CPC title

• G01S15/101

  Particularities of the measurement of distance (G01S15/12, G01S15/14, and G01S15/18 take precedence) · CPC title

• G01S13/28

  with time compression of received pulses · CPC title

• G01S13/10

  using transmission of interrupted, pulse modulated waves (determination of distance by phase measurement G01S13/32) · CPC title