Abstract: A first aspect of the present invention is carbon fiber wherein the surface of a monofilament has a center line average roughness Ra of 6.0 nm or more and 13 nm or less, and the monofilament has a long diameter/short diameter ratio of 1.11 or more and 1.245 or less. A second aspect of the present invention is carbon fiber precursor acrylic fiber wherein the surface of a monofilament has a center line average roughness Ra of 18 nm or more and 27 nm or less, and the monofilament has a long diameter/short diameter ratio of 1.11 or more and 1.245 or less. The carbon fiber according to the first aspect is obtained by stabilizing and carbonizing under specific conditions the carbon fiber precursor acrylic fiber according to the second aspect.

Abstract: In a weather radar system wherein echo signals are linear-detected from the waves received at the radar, each one of echo signals being compared with the later one to derive AC component, and the mean power of the weather echo estimated from the power of the AC component, the linear-detected echo signals are amplitude suppressed before compared. The amplitude suppression effectively removes the errors due to the fluctuation of ground clutter, and the variation of AC power of weather echo due to the existence of ground clutter. An amplitude suppressor is used which has an amplitude suppressing property expressed by Y=X.sup.k, where X is an amplitude of the input signal, Y is an amplitude of the output signal, and k is a constant (0<k<1). The value of k is advantageously 0.3-0.9, and, more advantageously 0.6-0.7. If the echo signals are obtained in a form of a logarithmic signal, an amplitude suppressor which has an input-output characteristic expressed by, for example, Y=10.sup.

Abstract: The present invention relates to a counter feed mechanism as used in digital clock comprising a cam member adapted for advanced rotation and another cam member adapted for delayed rotation both arranged on a common axis so that the advanced rotation of the first-mentioned cam member under a drive force transmitted from a clock mechanism twists a coil spring stretched between both cam members, which is, in turn, charged with energy for rotation of the second-mentioned cam member and, upon rotary displacement of the first-mentioned cam member by a predetermined angle, said second cam member is released to be rotated at once so as to advance a rotary wheel step by step.