Abstract: A pulse code modulation communication system adapted in a preferred embodiment to the remote control of a flying model aircraft. The positions of the various control sticks are represented by a digital code which is multiplexed and then transmitted via pulse code modulation of a unique subcarrier signal. The unique subcarrier signal is locked onto by the receiver which, through correlation detection, detects and demultiplexes the digital code for use by the servo motors to position the flight control surfaces of the aircraft.

Abstract: The winning tool carried for universal movement by the frame of a tunneling machine is controlled by a system and method to limit tool movement in a manner to form a tunnel with a desired cross section. Positioning of the winning tool is determined in relation to a laser beam projecting along the length of the tunnel while the range of universal movement by the winning tool is limited by a set of tool coordinate values determined by scanning a pattern, template or the like defining an outline that is geometrically similar to the desired cross section of the tunnel. The tunneling machine carries a receiver for the laser beam that irradiates front and rear detectors each including an array of photodetectors. Servomotors respond to an output signal from the front detector to align the receiver by a translating motion so that the laser beam passes through a single passageway in the front detector to irradiate the rear detector.

Abstract: In a frequency selective steering system for automatic vehicle guidance, a phase locked loop is used to derive from a sum signal containing wanted and unwanted signal frequencies a reference signal equal in phase and frequency to the wanted signal. The reference signal is used to derive from a difference signal also containing wanted and unwanted signal frequencies an error signal dependent on the phase of the wanted signal only. The error signal is used to control the steering of the vehicle.

Abstract: A wheelchair mounted control system may be activated to enable propelling of the wheelchair at different predetermined speeds, to cause portions of the wheelchair to recline or be elevated, or to cause a signal to be generated to operate other apparatus such as a book page turner, a light switch or a television tuner, merely by positioning the neck or other skin-exposed body portion of a person in the wheelchair who is otherwise largely incapable of movement. Particular structure includes a periodic electric field source and a pair of field pickup elements adapted to be selectively contacted by the skin of a movable portion of the disabled person's body to cause, for example, activation of stepping switches and associated control relays whereby wheelchair drive motor speed is preselected and recline/elevation motor apparatus is activated for effecting the desired control of various adjustable portions of the wheelchair.

Abstract: An electromagnetic field which nutates about a pointing vector is used to both track or locate a remote object in addition to determining the relative orientation of the object. Apparatus for generating such a field includes mutually orthogonal dipole radiators, defining a reference coordinate frame, and circuitry for supplying excitations, such that the maximum intensity vector of a vector field produced by these excitations in the radiators nutates about a mean axis or axis of nutation which is called the pointing vector direction of the field. A pointing coordinate frame has the x-axis coincident with the pointing vector and the y-axis in the x-y plane of the reference frame. Mutually orthogonal sensors at the object sense the field and establish a sense coordinate frame, which can be coincident with the coordinate frame of the remote body.

Abstract: A guidance system for controlling the path of a boat comprising a first conductor disposed below the surface of water in a first elongated loop and connecting at the terminals thereof across an A.C. source of electrical signal and a second conductor driven in a quadrature with the first conductor and disposed in a second loop partly superposed over the first loop. A first and second orthogonal inductive coil, mounted in the boat along a plane parallel to the loop and a plane normal to the loop plane and substantially parallel to the centerline thereof sense the vertical and horizontal components of the electromagnetic field generated about the conductor loops to produce corresponding induced signals respectively varying in amplitude and phase according to the amplitude of the electromagnetic field and the position thereof.

Abstract: Apparatus for remotely controlling the motor tape drive mechanism of an audio tape recorder or the like. In one embodiment, the apparatus comprises a plurality of semiconductors controlled by a low-level logic circuit and a diode switching network for selectively varying the current through the forward drive motor and the rewind motor of the mechanism to properly tension the tape between a take-up reel and a rewind reel and to differentially brake the motors when switching from a particular mode of operation to "stop" or in case of power failure, thereby preventing tape spillage.