Guidance seeker for small spinning projectiles

A guidance seeker for a spinning projectile having an angular momentum vector, comprising:

• a) a lens for gathering radiation derived from a target;
• b) a reticle disposed behind said lens, said reticle having a pattern of concentric circles nutating about the projectile angular momentum vector such that radiation passing therethrough is modulated by a target image formed thereon as the image moves across said concentric circles;
• c) a detector coupled to said reticle for receiving the transmitted modulated radiation, said detector adapted to generate an output in response to the received modulated radiation;
• d) said lens, reticle and detector defining an optical axis, and said lens, reticle and detector for being disposed stationary with respect to the projectile;
• and
• e) means for processing said output from said detector to determine the deviation of the target image from said optical axis.

A guidance seeker for a spinning projectile having an angular momentum vector, comprising:

• a) an antenna array for receiving radiation reflected from a target and forming an image thereof, said antenna array having a response of concentric cone lobes, said antenna array and said concentric cone lobes for being disposed stationary with respect to the projectile and nutating with the projectile about the projectile angular momentum vector such that the received radiation is modulated by the target image as the image moves across said concentric cone lobes, said concentric cone lobes having an axis;
• b) a receiver coupled to said antenna array for detecting the modulated radiation;
• and
• c) means for processing the modulated radiation from said receiver to determine the deviation of the target image from the axis of said concentric cone lobes.

A guidance seeker for a spinning projectile having an angular momentum vector, comprising:

• a) first and second means for receiving radiation reflected from a target and forming respective images of the target, said first and second receiving means for being disposed stationary with respect to the projectile;
• b) said first and second receiving means each having a plurality of concentric circles about an axis and nutating about the projectile angular momentum vector such that the received radiation is modulated by the respective target image as the image moves across the respective concentric circles;
• c) first and second detectors coupled to respective first and second receiving means for receiving the respective modulated radiation, each of said first and second detectors adapted to generate an output in response to the received modulated radiation;
• d) means for switching between said first and second receiving means;
• and
• e) means for processing the output from one of said first and second means to determine the deviation of the respective target image from the respective axis.

A method for guiding a spinning projectile to a target, the projectile having an angular momentum vector, said method comprising the steps of:

• a) receiving radiation derived a target;
• b) forming an image of the target;
• c) providing a reticle having a plurality of concentric circles, said reticle being disposed stationary with respect to the projectile;
• d) nutating the plurality of concentric circles about the projectile angular momentum vector such that the received radiation is modulated by the target image as the image moves across the concentric circles;
• e) counting the number of circles crossed by the image per nutation cycle whereby the change of number of circles crossed between nutation cycles is proportional to the drift rate of the target image;
• f) determining the direction of drift rate of the image;
• and
• g) correcting the trajectory of the projectile.