High precision radar detection system and method

• US 4,929,958 A
• Filed: 07/26/1989
• Issued: 05/29/1990
• Est. Priority Date: 07/26/1989
• Status: Expired due to Term

• Current Assignee: Litton Systems Incorporated (Northrop Grumman Corporation)
• Original Assignee: Dalmo Victor Incorporated
• Inventors: Atkins, Paul V., Hodel, P. Lloyd
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Hellner, Mark
• Application Number:
  US07/386,417
• Time in Patent Office: 307 Days
• Field of Search: 342/432, 342/437, 342/445, 367/124, 367/126
• US Class Current: 342/432
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 3/28 using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals

Abstract

A radar detection system with four transducers accurately determines the azimuth angle of a radar emitting object. The three strongest signals from the four transducers are combined to generate two differential signal values. A table is provided which contains angle of arrival values associated with all possible combinations of the two differential signal values. To determine the angle or arrival of a particular object, an index value is derived from the corresponding pair of differential signal values, and that index value is used to select the record in the table with the angle of arrival of the object, relative to the transducer which received the strongest signal. The table also stores a signal measurement correction for each combination of the two difference signal values. The signal measurement correction is to adjust the measured signal strength when calculating the distance of the object from the radar detection system.

Claims

1. A radar detection system, comprising:

a set of four transducer means for receiving signals indicative of the location of an object;

sorting means coupled to said set of transducer means for selecting the first, second and third strongest of said received signals and for generating therefrom first and second differential signals, said first differential signal corresponding to the difference between the strongest and second strongest of said received signals and said second differential signal corresponding to the difference between the second strongest and third strongest of said received signals;

table means for storing at least one angular value corresponding to each of a predefined set of pairs of said two differential signals; and

lookup means coupled to said sorting means and said table means for retrieving from said table means an angular value corresponding to the differential signal values generated by said sorting means.

2. The system of claim 1 wherein

said table means includes means for storing a signal measurement correction value corresponding to each of said predefined set of pairs of said two differential signals;

said lookup includes means for retrieving from said table means a signal measurement correction value corresponding to the differential signal values generated by said sorting means; and

said system further includes distance calculation means, coupled to said lookup means and said set of transducer means, for generating a distance value using a predefined function of said strongest signal received by said set of transducer means and said retrieved signal measurement correction value.

3. The system of claim 1 including

angle calculation means coupled to said sorting means and said lookup means for adding said retrieved angular value to a predefined reference angle corresponding to the one of said transducer means which received said strongest signal.

4. A radar detection system, comprising:

a multiplicity of transducer means for receiving radar signals indicative of the location of an object;

sorting means coupled to said set of transducer means for selecting the first, second and third strongest of said received signals and for generating therefrom first and second differential signals, said first differential signal corresponding to the difference between the strongest and second strongest of said received signals and said second differential signal corresponding to the difference between the second strongest and third strongest of said received signals;

table means for storing a signal measurement correction value corresponding to each of said predefined set of pairs of said two differential signals;

lookup means coupled to said sorting means and said table means for retrieving from said table means a signal measurement correction value corresponding to the differential signal values generated by said sorting means; and

distance calculation means, coupled to said lookup means and said set of transducer means, for generating a distance value using a predefined function of said strongest signal received by said set of transducer means and said retrieved signal measurement correction value.

5. The system of claim 4 wherein

said table means includes means for storing at least one angular value corresponding to each of said predefined set of pairs of said two differential signals;

said lookup includes means for retrieving from said table means an angular value corresponding to the differential signal values generated by said sorting means; and

said system further includes angle calculation means coupled to said sorting means and said lookup means for adding said retrieved angular value to a predefined reference angle corresponding to the one of said transducer means which received said strongest signal.

6. A method of processing received radar signals in a radar detection system having a set of four radar signal transducers, the steps of the method comprising:

selecting the first, second and third strongest of the signals received by said four transducers and generating therefrom first and second differential signals, said first differential signal corresponding to the difference between the strongest and second strongest of said received signals and said second differential signal corresponding to the difference between the second strongest and third strongest of said received signals;

providing a table of angular values, with at least one angular value corresponding to each of a predefined set of pairs of said two differential signals; and

retrieving from said table an angular value corresponding to the values of said first and second differential signals.

7. The method of claim 6, further including the step of adding said retrieved angular value to a predefined reference angle corresponding to the one of said transducers which received said strongest signal.

8. The method of claim 6, further including the steps of

providing a table of signal measurement correction values corresponding to each of said predefined set of pairs of said two differential signals;

retrieving from said table of signal measurement correction values a signal measurement correction value corresponding to the differential signal values generated by said sorting means; and

generating a distance value using a predefined function of said strongest signal received by said set of transducers and said retrieved signal measurement correction value.