Abstract: A terrestrial (erecting) telescope that may be inexpensively manufactured with plastic lenses but which telescope will provide a high quality image. The telescope comprises an objective lens, usually a single plano-convex lens, mounted in an outer tube. The telescope further comprises an inner tube in which are fixed an erecting lens system and an eye piece lens system. The erecting lens system comprises two identical plastic lens elements with opposite spherical and aspherical surfaces. The spherical surfaces of the erector lenses are facing. The eye piece lens system comprises a Ramsden eye piece having two plano-convex lenses with facing spherical surfaces. The aperture stop is positioned equidistance between the lenses of the erector lens system.

Abstract: A radar target pattern recognizer which extracts a predetermined frequency range from a radar signal representation. A spectrum analysis is performed on the signal and then displayed relative to a logarithmic frequency scale with a subsequent comparison of the output with known target patterns.