Method and device in a radar system on a ship for correcting bearing errors caused by the lurching movements of the ship

Claim 1

A TARGET SEARCH RADAR SYSTEM FOR USE ON A LURCHING SHIP HAVING A FORE-AND-AFT AXIS AND AN ATHWART AXIS, SAID AXES INTERSECTING TO DEFINE A SHIP PLANE WHICH INTERSECTS A FIXED HORIZONTAL PLANE ALONG A CANT AXIS AND ROTATES ABOUT SAID CANT AXIS AS SAID SHIP LURCHES AND IS SUBSTANTIALLY COINCIDENT WITH SAID FIXED PLANE WHEN SAID SHIP IS IN A HORIZONTAL ATTITUDE, SAID TARGET SEARCH RADAR SYSTEM COMPRISING AN ANTENNA CONTINUOUSLY ROTATABLE THROUGH A SUBSTANTIAL SECTOR ANGLE IN SAID SHIP PLANE, MEANS FOR TRANSMITTING SIGNALS TO SAID ANTENNA AND RECEIVING TARGET ECHO SIGNALS THEREFROM SO THAT A REPRESENTATION OF THE TOTAL AREA SCANNED BY SAID ANTENNA INCLUDING TARGETS IS OBTAINED, A MEANS FOR DISPLAYING SUBSTANTIALLY ORTHOGONAL RANGE AND BEARING COORDINATES INCLUDING AN ELECTION BEAM, MEANS RESPONSIVE TO TARGET ECHO SIGNALS FOR INTENSITYMODULATING SAID BEAM, A DISPLAY SCREEN AND DEFLECTING CIRCUITS FOR DEFLECTING SAID BEAM ACROSS SAID DISPLAY SCREEN, SELECTION MEANS FOR SELECTING A CUT-OUT SECTION OF THE REPRESENTATION OF THE TOTAL SCANNED AREA, DEFLECTION DRIVE MEANS RESPONSIVE TO SAID SELECTION MEANS FOR TRANSFERRING SIGNALS TO SAID DEFLECTION CIRCUITS SO THAT SAID DISPLAY MEANS DISPLAY ONLY THE SELECTED CUT-OUT SECTION, AND CORRECTION-GENERATING MEANS FOR GENERATING A VOLTAGE WHICH IS RELATED TO THE DIFFERENCE BETWEEN THE ANGLE, IN SAID FIXED HORIZONTAL PLANE, BETWEEN THE DIRECTION TO THE TARGET WHOSE INDICATION IS VISIBLE ON SAID DISPLAY SCREEN AND SAID CANT AXIS AND THE ANGLE, IN SAID SHIP PLANE, BETWEEN THE DIRECTION OF SAID ANTENNA WHEN RECEIVING THE TARGET ECHO SIGNALS DISPLAYED ON SAID DISPLAY SCREEN AND SAID CANT AXIS.