Abstract: A desired non-linear, monotonic compression function is performed substantially symmetrically upon both polarities of an AC signal by a circuit having a plurality of limiting stages, each having input circuitry with like terminals connected in parallel to one another, and providing an output current proportional to the stage input voltage, with a gain constant decreasing for an increasing stage number. Each stage has output circuitry connected in parallel with one another and providing an output current proportional to the stage input voltage, with a gain constant decreasing for an increasing stage number. A single output stage converts the total current provided by the limiter stages to an output voltage.

Abstract: A high-resolution television system is described which provides twice the vertical resolution of present television standards and is compatible therewith. A high-resolution television camera substantially simultaneously provides information from each of a pair of adjacent scan lines; the luminance information of both lines is added to provide information for amplitude modulation onto a luminance carrier, while the difference in luminance of the two adjacent scan lines is utilized to modulate a carrier phased in quadrature with the luminance carrier. The chrominance values of both lines are added to modulate a chrominance carrier. The bandwidth of the resulting luminance and chrominance signals are compatible with that of a carrier modulated by a single raster line.

Abstract: A one-piece, collapsible, readily-portable and rapidly-erectable antenna includes a substantially-planar and electrically-conductive ground plane consisting essentially of a central base element and a plurality of electrically conductive assemblies uniformly spaced about and mounted on the base element, the assemblies being guided on telescoping support rods for movement between expanded and collapsed positions relative to the base assembly. An at-least-three-sided elongated frame structure has a first end mounted on the base element; the other end is movable toward and away from the base element between collapsed and expanded frame structure positions, to collapsibly support a conductive radiator portion, comprising a metal helix. The helix is extended when the frame structure is expanded and is retracted when the frame structure is collapsed.

Abstract: A tomographic x-ray imaging system comprises a large plurality of parallel data acquisition channels which integrate and digitize signals from an array of x-ray detectors. Calibration pulses are injected into each data acquisition channel to permit measurement of drift in electronic gain and dc offset parameters. Separate x-ray detectors continuously monitor the intensity of the x-ray source.The measured values for channel gains, dc offsets, and source intensity are fed to a digital computer where they are automatically combined with x-ray transmission data to compensate for system drift and extend the period between calibration measurements.

Abstract: A doubling mixer includes an input tuned circuit adjusted to the frequency of an input signal, an output tuned circuit tuned to the desired output frequency, and a local oscillator. Semiconductor switch means are interposed between said input and output tuned circuits, the switch means being responsive to the local oscillator to conduct twice during each cycle thereof. The relationship between the input and output signal frequencies as a function of the local oscillator frequency may be expressed as:F.sub.IF = F.sub.S .+-. 2 F.sub.

Abstract: A single, non-bandswitched local oscillator in a UHF, VHF, CATV television receiver tuner system is employed with frequency multiplying and, or frequency dividing to obtain the required IF frequencies. The tuner operates in a double frequency conversion mode at UHF frequency with a tuned VHF RF amplifier dual functioning as a UHF IF amplifier. A UHF preselector and the VHF RF amplifier are gang-tuned with the local oscillator. The tuner operates in a single frequency conversion mode at VHF and CATV frequencies, and one of the local oscillator frequency dividing or doubling stages is utilized to distinguish the VHF low band from the high VHF-CATV tuning band.