Abstract: A nuclear imaging system in which a substantially on-axis Fresnel zone plate positioned between a source of nuclear radiation in living tissue and a spatial detector is moved in a predetermined time sequence in synchronism with motion of a bar pattern formed at the spatial detector output to improve suppression of unwanted spatial frequency components and to facilitate production of an image of the nuclear source.

Abstract: A nuclear imaging system for mapping a spatially distributed source of high energy nuclear particles from a living organ which has selectively absorbed a radioactive compound in which the nuclear energy is spatially coded by a zone plate positioned between the source and a spatial detector, and a half tone screen is positioned between the source and the zone plate to increase the definition of the image.

Abstract: In a gamma camera having an array of photomultipliers coupled via pulse shaping circuitry and a resistor summing and weighting circuit to a display for forming an image of a radioactive target, the improvement being a modulation circuit for reducing the intensity of points on the display located at positions corresponding to positions of the photomultipliers for removing an apparent image of the array.

Abstract: In a navigation system in which a beam of radiation is utilized for communicating information to a vehicle, such as an aircraft approaching a landing strip, there is provided a pseudo-noise generated binary code having sequentially generated bits ordered in a sequence of nonrepeating subsequences with each of these bits uniquely representing a value of a coordinate describing the position of the beam of radiation. For example, with an azimuthally scanned beam of radiation, each bit in the code represents an increment in the azimuth angle while the digits of one of the subsequences is sufficient to uniquely determine the azimuth angle. An encoder and a decoder, each similarly structured with a shift register and feedback logic, are disclosed.

Abstract: A system for communicating a data channel composed of a multiplicity of telephone-type messages wherein the invention incorporates circuitry for modulating service channel data onto a carrier of the telephone channel data and for demodulating the service data without interfering with the telephone data. An inverse modulator driven by detected telephone data is utilized to recover a carrier which is then tracked by a tracking filter to recover the service data.

Abstract: An apparatus for activating a remote underwater device comprising detecting means responsive to incident acoustic waves provides signal indication of the presence or absence of predetermined frequencies thereof. A logic arrangement decodes only those signal indications indicating a joint presence of some of the pre-selected frequencies and the absence of others of the pre-selected frequencies. This discriminates signals against broad-band acoustic noise. The logic arrangement further includes means for activating the remote underwater device only if the decoded successive signal indications match a predetermined pattern. This further discriminates between a present received acoustic wave and a prior transmitted acoustic wave present because of multipath or reverberation. Lastly, a timing and gating means responsive to a first decoded signal indication couples the detecting means to the logic arrangement only at periodic intervals thereafter.

Abstract: A radiographic imaging system for high energy radiation utilizing a detector of such radiation and a mask having regions relatively transparent to such radiation interspersed among regions relatively opaque to such radiation. A relative motion is imparted between the mask and the detector, the detector providing a time varying signal in response to the incident radiation and in response to the relative motion. The time varying signal provides, with the aid of a decoder, an image of a source of such radiation.