Radar target signature detector

• US 5,191,343 A
• Filed: 02/10/1992
• Issued: 03/02/1993
• Est. Priority Date: 02/10/1992
• Status: Expired due to Fees

• Current Assignee: Siemens Rail Automation Ltd. (Siemens AG)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Brienza, Michael J., Danzer, Paul M.
• Primary Examiner(s): TUBBESING, THEODORE
• Application Number:
  US07/836,668
• Time in Patent Office: 386 Days
• Field of Search: 342/21, 342/59, 342/192, 342/193
• US Class Current: 342/21
• 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 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 7/41 using analysis of echo signal for target characterisation; Target signature; Target cross-section

Abstract

An improved radar system utilizing the principle of nonlinear contact effects for detecting and identifying a target, includes two radar transmitters (12,16) at least one of which is a baseband pulse radar transmitter. Both transmitters illuminate the same target and the signals from each transmitter are mixed in a nonlinear junction (40) of the target. Mixing the two signals provides a target return signal whose frequency spectrum contains cross product frequency components having high resolution target data due to the broad spectral content of the baseband pulse, and thus provides a system capable of detecting and identifying the illuminated target.

Claims

1. An improved radar target signature detector, comprising:

a baseband radar transmitter which provides a baseband pulse of electromagnetic energy;

a baseband pulse radar antenna for radiating said baseband pulse of electromagnetic energy to illuminate the target;

a wide pulse radar transmitter which provides a wide pulse of electromagnetic energy having a certain carrier frequency;

a wide pulse radar antenna, capable of both radiating and receiving, for radiating said wide pulse of electromagnetic energy to illuminate the target, such that said wide pulse and said baseband pulse mix within one or more nonlinear junctions of the target and generate a target return signal of electromagnetic energy whose frequency spectrum contains cross product frequency components having high resolution target data created by mixing said baseband pulse and said wide pulse, and for receiving said return signal and providing a captured return signal indicative thereof; and

a radar receiver which receives said captured return signal and filters said captured return signal to provide a filtered signal from which the target can be both detected and identified.

2. The improved radar target signature detector of claim 1, wherein said baseband radar transmitter comprises means for generating a pulse having a pulse width no more than several nanoseconds within a baseband of approximately one megaHertz to one gigaHertz, such that said baseband pulse signal has a frequency spectrum of about one megaHertz to one gigaHertz.

3. The improved radar target signature detector of claim 1, wherein said baseband radar transmitter comprises means for generating a pulse having a pulse width no more than four nanoseconds within a baseband of approximately one megaHertz to one gigaHertz, such that said baseband pulse signal has a pulse width no more than four nanoseconds within a baseband of approximately one megaHertz to one gigaHertz.

4. An improved radar target signature detection system, comprising:

a conventional radar transmitter that provides a relatively wide pulse of electromagnetic energy impressed on a carrier signal of a certain frequency, where the width of said wide pulse is a certain time period T;

a baseband pulse radar transmitter that provides a baseband pulse of electromagnetic energy having a pulse length which is much smaller than the dimensions of the target, wherein said baseband pulse is provided within said certain time period T such that said baseband pulse illuminates the target together with said wide pulse;

a first antenna for radiating said baseband pulse of electromagnetic energy to illuminate the target;

a second antenna for radiating said wide pulse of electromagnetic energy to illuminate the target such that said wide pulse and said baseband pulse mix within one or more nonlinear junctions of the target, generating cross product frequency components having high resolution target data within a reradiated target return signal of electromagnetic energy, and for receiving said return signal and providing a captured return signal indicative thereof;

a bandpass filter, for filtering said captured return signal, and for providing a bandpass signal indicative thereof; and

a stop band filter, for filtering said bandpass signal, and for providing a filtered signal whose frequency spectrum retains said high resolution target data from which the target can be detected and identified.

5. The improved radar target signature detector system of claim 4 wherein said baseband pulse radar transmitter comprises means for generating a pulse having a pulse width less than four nanoseconds, such that the pulse width of said baseband pulse signal is less than about four nanoseconds.

6. The improved radar target signature detection system of claim 5 wherein said baseband pulse radar transmitter comprises means for generating a pulse having a frequency spectrum of approximately one megaHertz to one gigaHertz, such that said baseband pulse has a frequency spectrum of approximately one megaHertz to one gigaHertz.

7. An improved radar target signature detector for both detecting and identifying a target, comprising:

a baseband pulse radar transmitter that provides a baseband pulse of electromagnetic energy containing frequency components within a certain baseband frequency spectrum;

a radar transmitter which provides a second pulse of electromagnetic energy having a pulse width T;

an antenna for radiating said baseband pulse to illuminate the target;

means for radiating said second pulse of electromagnetic energy to illuminate the target such that said baseband pulse and said second pulse simultaneously illuminate the target, and mix within one or more nonlinear junctions of the target generating cross product frequency components having high resolution target data within a reradiated target return signal of electromagnetic energy, and for receiving said return signal and providing a captured return signal indicative thereof;

a bandpass filter, for filtering said captured return signal, and for providing a bandpass signal indicative thereof; and

a stop band filter, for filtering said bandpass signal, and for providing a filtered signal whose frequency spectrum retains said high resolution target data from which the target can be detected and identified.

8. The improved radar target signature detector of claim 7 wherein said radar transmitter comprises means for generating a baseband pulse having a baseband spectrum of at least several hundred megaHertz, such that said second pulse has a baseband spectrum of at least several hundred megaHertz.

9. The improved radar target signature detector of claim 8 wherein said radar transmitter comprises means for generating a conventional radar pulse impressed on a carrier signal of a certain frequency, such that said second pulse is a conventional radar pulse on a carrier signal of said certain frequency.