Abstract: In a continuous wave Doppler system in which a fixed transmitter transmits a continuous wave signal to be reflected by moving targets and by fixed structure, an aircraft receives the reflective signals at two spaced apart antennas. The signals reflected from moving targets are distinguished from ground clutter reflected from fixed structure by the phase difference between the Doppler signals receive by the two antennas. The signals reflected from moving targets are distinguished from the ground clutter in response to the phase difference between the Doppler signals received by the two antennas being not equal to a phase difference value determined to be the phase difference for clutter signals. The phase difference value for clutter signals is determined from a function expressing the phase difference value as a linear variation with the Doppler frequency of the signals.

Abstract: A probe for a spectrometer has a slot for receiving a sample, an illuminating fiber optic bundle directing light to the sample in the slot, and first and second collecting fiber optic bundles transmitting light from the sample to the spectrometer, wherein the first collection fiber optic bundle is positioned to optimize the collection of transmitted light without scattering through the sample, and the second collection fiber optic bundle is positioned to optimize the collection of light diffusely reflected from the sample. In one embodiment, the first collection bundle is arranged in an annulus around the illuminating bundle, and the second collection bundle is arranged in an annulus around the first collection bundle. In a second embodiment, the second collection bundle is arranged in an annulus around the illuminating bundle, and the first collection bundle terminates in an interface with the sample located across the slot from the illuminating bundle and the second collection bundle.

Abstract: A heat exchanger comprises a gas casing formed with a gas chamber filled with a refrigerant gas, and a heat exchanging unit received in the gas chamber of the gas casing. The heat exchanging unit has a plurality of regenerative plates each made of a material having a thermal conductivity and a heat capacity. The regenerative plates are positioned in face-to-face and thermally insulated relationships to one another with the surfaces being in substantially perpendicular to the center axis of the heat exchanging unit to define spaces each between the neighboring two regenerative plates. Each of the regenerative plates may be shaped in the symmetrical outline form with respect to its central point and smaller in size than the cross-sections of the gas chamber of the gas casing. Each of the regenerative plates has a plurality of airy holes formed therein.