Abstract: An optical reading head is described which is particularly designed to read codes generally formed by fluorescent or phosphorescent bars. The codes are carried by a support, such as an envelope which moves past the head at a relatively high speed. The support carrying the code is illuminated from a light source through a set of outgoing optical fibers, and the modulated light retransmitted by the code markings is conveyed through a set of incoming optical fibers to a processing device. Such a reading head is particularly adapted for use in a postal sorting system.

Abstract: A method and an apparatus for determining in a radar system the optimum eination threshold for suppressing permanent echoes are described. A basic elimination threshold is defined which is modified once per revolution of the radar antenna or several times during each revolution in each area covered by the radar system, by the addition or the subtraction of a coefficient depending on the comparison of the amplitude of the video signals with a previously set threshold. Then the residual clutter rate is calculated for each revolution of the antenna and also for each area covered and is compared with two fixed values, i.e. an upper and lower limit. A coefficient is derived from this comparison and is added to or subtracted from this previously set normal threshold, depending on whether the result of the comparison, is less than the minimum-rate value or greater than the maximum-rate value.

Abstract: A light-conducting fiber, or a bundle of such fibers, is provided with a ht-absorbing shield extending beyond an end face of the fiber or bundle proximal to a light-reflecting object. The shield forms a light-guiding channel, of a length substantially exceeding its width, which limits the effective aperture angle of the fiber or bundle to considerably less than its inherent value on the order of 60.degree..