Abstract: This arrangement is formed by two receive branches (1) and (4) for receiving a wave whose frequency spectrum is practically constant in a predetermined frequency band, a combining circuit (15) for combining the waves at the output of the receive branches and a servo-control for keeping the spectrum of the signal at the output of the combining circuit constant by adjusting a phase shifting circuit (12) inserted in said branch (4). The servo-control is constituted by a frequency discrimination circuit (25) for analyzing the combined waves, an adjustable selective circuit (27) for obtaining a frequency band of the spectrum of the combined signal as a function of the output signal of the frequency discriminator and by a control circuit (29, 31) which adjusts the phase shifting circuit for optimizing the output signal of the selective circuit.

Abstract: An anti-lock brake control system for a vehicle with braked wheels comprises a sensor to produce a signal proportional to the deceleration/acceleration of the braked wheel, a deceleration sensing switch to respond to the deceleration/acceleration signal by producing a brake pressure release pulse when deceleration of the wheel exceeds a predetermined threshold level, a charge storage device which is adapted so that it charges in a predetermined progressive manner while the brake pressure release pulse is produced and discharges at a predetermined decay rate, a comparator that compares the potential on the charge storage device with a reference potential and produces an extension brake pressure release pulse according to their relative values, and apparatus to vary one of said potentials in a manner dependent on acceleration of the wheel above a preset acceleration threshold so that the extension brake pressure release pulse is terminated by increasing wheel acceleration.

Abstract: Window structure in which the aperture incorporated in package slide is left open, the scanning window being recessed below and to one side of the aperture, making a substantial angle with the plane of the slide and located to join at one edge of the aperture. A removable receptacle located with debris catching portions below the scanning window can be provided for ease of cleaning.