UWB dual tunnel diode detector for object detection, measurement, or avoidance

• US 6,239,741 B1
• Filed: 07/20/1998
• Issued: 05/29/2001
• Est. Priority Date: 07/20/1998
• Status: Expired due to Term

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Multispectral Solutions Incorporated (Zebra Technologies Corporation)
• Inventors: Fontana, Robert J., Larrick, J. Frederick, Cade, Jeffrey E.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/118,919
• Time in Patent Office: 1,044 Days
• Field of Search: 342/21, 342/27, 342/28, 342/70, 342/71, 342/72, 342/118, 342/134, 342/135, 342/175, 342/195, 342/13, 342/89, 342/93, 375/130-153, 375/295, 375/309, 375/316, 375/338, 375/340
• US Class Current: 342/135
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/10 using transmission of interrupted, pulse modulated waves determination of distance by phase measurement G01S13/32
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/4078 involving an integrated reference reflector or reference transponder

Abstract

A highly sensitive, high-speed dual tunnel diode detector is described for use in Ultra Wideband (UWB) object detection systems, such as a radar. The extended capability of the detector to both extremely short (sub-foot) and long distance (tens of thousands of feet) ranges is unique and permits the application of low power UWB radar to a wide variety of applications including high resolution radar altimetry at altitudes exceeding 10,000 feet and for autonomous on-deck landing operations (e.g., one-foot altitudes), the detection of extremely low radar cross section (RCS) targets for such applications as suspended wire detection for helicopters and other manned and unmanned craft, etc. High noise and interference immunity of the detector permits co-location of a UWB radar sensor with other active systems. The invention has immediate and significant application to all areas, both military and commercial, of precision distance measurement, intrusion detection, targeting, etc. over a wide range of distances.

Claims

1. An object detector comprising an ultra wideband pulse source, a first tunnel diode detector that detects a primary pulse transmitted by said source, and a second tunnel diode detector having a gate that is opened in response to detection of said primary pulse by said first tunnel diode detector thereby to enable the second tunnel diode detector to detect a reflected pulse from an object.

2. The object detector as recited in claim 1 further including a microcontroller that controls an initiation of said pulse source and opening of said first and second gates of said tunnel diode detectors.

3. The object detector as recited in claim 1, further including a receiver connected with said second tunnel diode detector that receives said second reflected pulse.

4. The object detector as recited in claim 1, further including a receiver that receives the primary and reflected pulses, a switch connected with the receiver that alternately routes received pulses to one of said first and second tunnel diode detectors, and processing circuitry that controls the switch according to detection of the primary pulse.

5. A method of short-range detection of an object comprising the steps of generating an ultra wideband pulse, gating a first ultra wideband detector to receive a transmit pulse during a transmit interval, gating a second ultra wideband detector to receive a reflected pulse during a receive interval that is determined in response to detection of said transmit pulse by said first ultrawide band detector, and determining the range of said object according to a time difference between detecting the transmit and reflected pulses during the respective transmit and receive intervals.

6. The method as recited in claim 5 further including the step of providing mutually exclusive transmit and receive intervals in which to detect said transmit and reflected pulses.

7. The method as recited in claim 5 further including the step of providing multi-stepped delays during said receive interval and detecting the characteristic of delayed outputs thereof in order to ascertain fine gradations of range of detection of said object.

8. The method as recited in claim 5 further including the step of time-displacing said receive interval during a period of desired range detection.

9. The method of claim 5, wherein said first and second ultra wideband detectors comprise tunnel diodes.

10. A radar altimeter utilizing ultra wideband pulses comprising:

an ultra wideband pulse source,

a first ultra wideband detector that detects a primary pulse transmitted directly from said source,

a second ultra wideband detector that detects a reflected pulse from a surface, and

processing circuitry that controls said first detector to detect said primary pulse during a transmit interval and that controls said second detector to detect reflected pulses during a receive interval that is determined based on detection of said primary pulse during said transmit interval, and or determining a time difference between detection of said primary and reflected pulses whereby to ascertain a distance-to-surface measurement.

11. The radar altimeter as recited in claim 10 wherein said digital processor includes a time detector including a multi-tapped delay line connected at the output of at least one of said first and second detectors for providing a representation of multiple gradations of distance measuring signals.

12. The radar altimeter as recited in claim 10 wherein said digital processor uses said transmit pulse as a timing reference signal.

13. The radar altimeter as recited in claim 10 including a common transmit and receive antenna in communication with said ultra wideband pulse source and said first and second ultra wideband detectors.

14. The radar altimeter as recited in claim 10, wherein said first and second ultra wideband detectors comprise tunnel diodes.

15. An object detection system for ascertaining a distance measurement, said system comprising:

an ultra wideband pulse source,

a first ultra wideband detector that detects a primary pulse transmitted directly from said source,

a second ultra wideband detector that detects a reflected pulse from an object, and

a controller that controls said first detector to detect said primary pulse during a transmit interval and that controls said second detector to detect said reflected pulse during a receive interval that commences in response to detection of said primary pulse during said transmit interval, and for determining a time difference between detection of said primary and reflected pulses whereby to ascertain a distance measurement.

16. The object detection system as recited in claim 15 wherein said controller determines said time difference using said primary pulse as a time reference signal.

17. The object detection system as recited in claim 15 including a common transmit and receive antenna in communication with said ultra wideband pulse source and said first and second ultra wideband detectors.

18. The object detection system as recited in claim 15, wherein said first and second ultra wideband detectors comprise tunnel diodes.

19. An object avoidance system comprising:

an ultra wideband pulse source,

a first ultra wideband detector that detects a primary transmit pulse transmitted directly from said source,

a second ultra wideband detector that detects a reflected pulse from an object, and

a digital processor that controls said first detector to detect said primary pulse during a transmit interval and that controls said second detector to detect said reflected pulse during an adjustable receive interval following detection of said primary pulse during the transmit interval, said digital processor generating an alarm upon detection of an objection within said adjustable receive interval.

20. The object avoidance system as recited in claim 19 wherein said digital processor uses said primary transmit pulse received by said first detector as a timing reference signal to adjust said adjustable receive interval.

21. The object avoidance system as recited in claim 19 further including a multi-tapped delay line to generate representations of gradations of distance measurements of an object within said adjustable receive interval.

22. The object avoidance system as recited in claim 19 further including a common transmit/receive antenna in communication with said pulse source and said first and second detectors.

23. The object avoidance system as recited in claim 19, wherein said first and second ultra wideband detectors comprise tunnel diodes.

24. An object detection system using ultra wideband pulses for measuring the range of an object, said detector comprising:

an ultra wideband pulse transmitter including a transmit antenna,

an ultra wideband receiver having a receive antenna and an RF module that amplifies signals received by said receive antenna,

a dual tunnel diode detector module that receives amplified signals from said RF module, said dual tunnel diode module including a transmit tunnel diode that receives a transmit pulse transmitted directly from said pulse transmitter to said receive antenna and a receive tunnel diode that receives a reflected pulse from said object, and a switch that routes signals received by said RF module either to said transmit tunnel diode or to said receive tunnel diode, and

a digital processor that controls the operation of said pulse transmitter and said dual tunnel diode detector module by generating timing pulses that initiate transmission of ultra wideband pulses from said pulse source and that activate the transmit tunnel diode to receive a transmit pulse and the receive tunnel diode to receive a reflected pulse during mutually exclusive transmit and receive intervals, respectively, each of said receive intervals being initiated according to detection of said transmit pulse during a transmit interval, said digital processor further performing operations to calculate the range of the object according to the time-difference between detection of said transmit and reflected pulses.

25. The object detection system as recited in claim 24, wherein said first and second ultra wideband detectors comprise tunnel diodes.