Enhancing radar returns from targets having a small radar cross section

• US 4,193,074 A
• Filed: 12/03/1974
• Issued: 03/11/1980
• Est. Priority Date: 12/03/1974
• Status: Expired due to Term

• Current Assignee: Calpine Corporation
• Original Assignee: Calpine Corporation
• Inventors: Leney, Thomas F., Schwartz, Edward C.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/530,566
• Time in Patent Office: 1,925 Days
• Field of Search: 343/16 M, 343/16 LS
• US Class Current: 342/149
• CPC Class Codes: G01S 13/449 Combined with MTI or Doppler processing circuits

Abstract

A method for locatingweak targets such as power lines and tree tops in the presence of terrain clutter by separating the weak target from the clutter in the elevation plane.

Claims

1. A method for locating one target in the presence of a second target such as clutter which is present and unresolved in the same pulse packet by separating said targets in the monopulse plane including the steps of:

directing a radar antenna boresight at said second target;

alternately, cyclically transmitting a radar signal in sum and difference pattern; and

processing return signals, whereby, if said one target is present in any pulse packet and located in one of the lobes of the difference pattern transmission, the signal to clutter ratio in said return signals from said one target will be greater when transmission is in the difference pattern than in the sum pattern when there is an angular separation between said one target and said second target in the monopulse plane, and, thereby the presence of said one target will be identified and said one target located.

2. A method for locating a weak target in the presence of terrain clutter in the same pulse packet for use in a monopulse radar terrain-following system including the steps of:

directing the radar antenna boresight at the terrain that is at the range of said weak target;

alternately, cyclically transmitting a radar signal in an elevation sum and an elevation difference pattern; and

processing return signals, whereby, if a weak target is present in any pulse packet and located in one of the lobes of the difference pattern transmission, the signal-to-clutter ratio in the return signals from said weak target will be greater from transmissions in the elevation difference pattern than in the elevation sum pattern when there is an angular separation between the weak target and the terrain clutter in the elevation angle, and, thereby the presence of the weak target will be identified and said weak target located.

3. A method for locating one target in the presence of a second target in a pulse packet by separating said targets in the elevation plane including the steps of:

directing a radar antenna boresight at said second target;

alternately, cyclically transmitting a radar signal in an elevation sum and an elevation difference pattern; and

processing return signals, whreby, if said one target is present in any pulse packet and located in one of the lobes of the difference pattern transmission, the signal to clutter ratio in said return signals from said one target will be greater when transmission is in the elevation difference pattern than in the elevation sum pattern when there is an angular separation between said one target and said second target in the elevation angle, and, thereby the presence of said one target will be identified and said one target located.

4. A method for locating one target in the presence of a second target in the same pulse packet by separating said targets in the monopulse plane including the steps of:

directing a radar antenna boresight at said second target;

transmitting a radar signal in difference pattern; and

processing return signals, whereby if said one target is present in any pulse packet and located in one of the lobes of the difference pattern transmission, return signals from said one target will be maintained while return signals from said second target will be suppressed and thereby the presence of said one target will be identified and said one target located.