Satellite tracking antenna apparatus

Apparatus for controlling the position of a body which comprises

• means for mounting said body for rotation about at least two mutually orthogonal axes,
• means rotatable with said body about said axes defining a platform rotatable with respect to said body about a third axis parallel to or collinear with a first of said two axes,
• sensor means mounted on said platform for sensing orientation of said body about each of said two axes with respect to the vertical,
• servo control means responsive to said sensor means for rotating said body about said two axes to maintain said platform level,
• means for rotating said platform about said third axis to vary the relative angle between said third axis and said first axis, whereby said sensor means operate said servo control means to rotate said body to change the attitude thereof to correspond to said relative angle,
• said sensor means including means mounted on said platform responsive to the angular motion of said body with respect to said two axes,
• means also mounted upon said platform for sensing the angular position of said body about a fourth axis, which is mutually perpendicular to said two axes, with respect to a reference position and providing an output corresponding thereto,
• means mounted upon said platform for sensing the angular motion of said body about said fourth axis and for providing an output corresponding thereto, said servo control means including means responsive to said outputs from said means for sensing said angular position and motion about said fourth axis to rotate said body to maintain said body at said reference position, and
• means for varying said output from said angular position sensing means to which said servo control means is responsive to rotate said body about said fourth axis to positions other than said reference position.

For use on a ship or the like for mounting a directional antenna which is adapted to be trained to point to a satelliteborne transmitting station to maintain communication therewith, said apparatus comprising means mounting said antenna for rotation about a plurality of mutually orthogonal axes, means coupled to said mounting means for rotating said antenna about each of said axes, means for sensing the orientation of said antenna, means defining a platform for mounting said sensing means for movement with said antenna and for rotation about an axis parallel to or collinear with one axis of said plurality of axes, servo control means responsive to said sensing means for operating said rotating means to keep said platform means level, means for rotating said platform means to change the attitude thereof about the axis of rotation of said platform whereby to cause said servo control means to change the attitude of said antenna with respect to said one axis, said antenna being directional along a boresight axis, said plurality of axes includes an elevation axis which is perpendicular to the boresight axis of said antenna and a cross level axis, the axis of said platform being the level axis, said means for rotating said platform means being operative to cause said servo control means to vary the elevation angle of said boresight axis, said mounting means mounting said antenna for rotation about a train axis so that said boresight axis is movable in azimuth, said rotating means including azimuth motor means coupled to said mounting means for rotating said antenna about said train axis, compass means mounted on said platform means for providing an azimuth output corresponding to the relative bearing of said platform means with respect to a reference direction, said servo control means including a train channel for applying said azimuth output to said azimuth motor means for rotating said antenna about said train axis, and means for setting the direction of said antenna in azimuth included in said train channel for varying said azimuth output to correspond to an azimuth setting.

For use on a ship or the like for mounting a directional antenna which is adapted to be trained to point to a satelliteborne transmitting station to maintain communication therewith, said apparatus comprising means mounting said antenna for rotation about a plurality of mutually orthogonal axes, means coupled to said mounting means for rotating said antenna about each of said axes, means for sensing the orientation of said antenna, means defining a platform for mounting said sensing means for movement with said antenna and for rotation about an axis parallel to or collinear with one axis of said plurality of axes, servo control means responsive to said sensing means for operating said rotating means to keep said platform means level, means for rotating said platform means to change the attitude thereof about the axis of rotation of said platform whereby to cause said servo control means to change the attitude of said antenna with respect to said one axis, said antenna being directional along a boresight axis, said plurality of axes includes an elevation axis which is perpendicular to the boresight axis of said antenna and a cross level axis, the axis of said platform being the level axis, said means for rotating said platform means being operative to cause said servo control means to vary the elevation angle of said boresight axis, said level sensor means including a first level sensor responsive to the position of said platform with respect to said elevation axis for providing an elevation position output and a second level sensor responsive to the position of said platform with respect to said cross-level axis for providing a cross level position output, said rotating means including elevation motor means coupled to said mounting means for rotating said antenna about said elevation axis, cross-level motor means coupled to said mounting means for rotating said antenna about said cross-level axis, said servo control means including an elevation channel and a cross-level channel respectively for applying said first level sensor output to said elevation motor means and said second level sensor output to said cross level motor means, said sensor means also including a first rate sensor responsive to angular motion of said platform means about said elevation axis and a second rate sensor responsive to angular motion of said platform means about said cross level axis, said elevation channel including a position loop responsive to said first level sensor and a rate loop responsive to said first rate sensor, said loops in said elevation channel providing a signal for controlling said elevation motor means, said cross-level channel including a position loop responsive to said second level sensor and a rate loop responsive to said second rate sensor, and said loops in said cross level channel providing a signal for controlling said cross level motor means.

For use on a ship or the like, apparatus for mounting a directional antenna having a boresight axis which is adapted to be trained towards a satellite-borne transmitting station to maintain communication therewith, said apparatus comprising

• a pedestal adapted to be secured to the structure of said ship,
• a section journaled on the pedestal for rotation about a train axis perpendicular to the deck of said ship,
• a yoke rotatably mounted on said section for rotation about a cross-level axis,
• a support structure in which said antenna is held, said support structure being mounted on said yoke for rotation about an elevation axis,
• said elevation axis, cross elevation and train axes being mutually orthogonal, said elevation axis also being orthogonal to said boresight axis,
• a unit mounted on said support structure for rotation about a level axis which extends in the same direction as said elevation axis and in mutually orthogonal relationship with said cross-level and train axes,
• separate train, cross-level elevation and level motors respectively in rotational driving relationship with said section, said yoke and said support structure,
• an elevation level sensor, a cross level sensor, and an azimuth sensor mounted in said unit, said unit defining a level platform for said sensors, said sensors providing a separate elevation, cross level and azimuth outputs corresponding to the angular position of said platform with respect to said elevation and cross-level axes and with respect to a reference azimuthal direction,
• an elevation channel and a cross level channel respectively responsive to said elevation sensor output and said cross level sensor output for controlling said elevation and cross level motors to rotate said support structure and said yoke to maintain said platform level,
• means for setting the elevation angle of said boresight axis operative to control said level motor to rotate said level platform to an angle equal and opposite to said elevation angle whereby to cause said elevation sensor to provide an elevation output to said elevation channel to cause said elevation motor to rotate said support structure until said bore sight axis reaches said elevation angle, and
• a train channel responsive to said azimuth sensor output and to a control signal corresponding to the direction azimuth of said boresight axis for controlling said azimuth motor to rotate said section until it reaches said azimuth direction.