Abstract: An apparatus for sensing the proximity of a moving target is provided which includes a sensor for sensing a range of distances between a reference point and a moving target. The sensor preferably has a detector for detecting a distance signal representative of a range of distances between a reference point and a moving target and a maximum and minimum generator responsive to the detector for generating a maximum distance range DC voltage signal representative of a maximum distance range value between a reference point and a moving target and for generating a minimum distance range DC voltage signal representative of a minimum distance range value between a reference point and a moving target.

Abstract: A method and apparatus for sensing proximity of an object using near-field effects. Modulated radio frequency energy is fed to an antenna. The antenna radiates this modulated radio frequency energy to charge the surface of an object. When the position of the object changes, the impedance of the antenna due to near-field effects changes. This impedance change is detected to provide an indication of the object's movement. The sensing device may be packaged to be inserted into a wall to provide a sensor having a leak-free seal.

Abstract: Apparatus for modulation of optical signals at millimeter-wave frequencies comprises a thin elongate dielectric slab (1) of lithium niobate to partially confine and guide therein a polarized electrical signal (8) at millimeter-wave frequencies; a thinner optical waveguide (3) of lithium niobate with titanium diffused therein to substantially confine and guide therein an optical signal (9), having at least one elongate surface adjacent to an elongate surface of the dielectric slab (1); an optical grating (5) of arsenic trisulfide for directing a polarized optical signal (9) into the waveguide (3) to propagate in a lengthwise direction therein; an optical grating (7) of arsenic trisulfide for directing the optical signal (9) out of the waveguide (3) after it has traversed a predetermined distance therein; and a metallic waveguide (2) for directing an electrical signal (8) into the dielectric slab (1) in the same direction as that of the optical signal (9) in the waveguide (3), and at a center frequency such tha

Abstract: A method for detecting the polarized potential of a buried pipe which is cathodically protected by rectified alternating current impressed upon the pipe. Each rectified protection current is periodically pulsed to an off state for a precise pulse duration and pulse period which are integral multiples of the period of the alternating current. The potential between the pipe and a reference electrode at the test site is sampled and analyzed to detect the polarized potential. It is analyzed to find the area under the portion of the waveform during which no off pulses are present and to use that area to detect the on potential. The area within the off pulses, after reactive spikes are eliminated, is substracted from the on potential area to determine the IR drop potential. The IR drop potential is then subtracted from the on potential and the difference is displayed as the polarized potential.

Abstract: The polarized potential at the boundary between a submerged pipe and a medium is measured unaffected by the presence of a distributed IR drop in the medium due to an impressed current from a corrosion protection system. The voltage between the pipe and a reference electrode in the medium is measured when the protection system current is zero. This is accomplished with a sample-and-hold circuit controlled by a trigger signal derived from the input signal and having a variable phase for controlling the phase angle at which the sample is taken.