Abstract: A system and method to open and/or close a garage door enables a receiving unit to activate a door opening and/or closing operator mechanism in response to receiving a signal. The transmitting unit transmits a signal to the receiving unit in response to a pulsed light signal.

Abstract: Method for determining the position and depth of unevenness in an inner surface of a pipe with the aid of a scanning head which is adapted to travel through the pipe and which is rotatable about the pipe axis. The invention provides an inductive, or capacitive, depth scanning process, which operates in a contact-free manner with respect to the inner pipe surface. This is attained by means of an inductive method in that, as is illustrated in the drawing, there is arranged at a distance from the pipe inner surface the scanning head which is guided and in which a coil (2) of a measuring, resonant circuit is mounted and, above the inner periphery of the pipe, a coil 1 of a reference, resonant circuit is arranged, and then, after the frequencies of both resonant circuits have been brought, prior to measuring, to an identical value in each of a multiplying circuit (10, 7, 13 respectively 11, 8, 14), they are measured and converted into an adjustable difference of the multiplied frequencies (f.sub.1, f.sub.

Abstract: A process and arrangement for introducing an automatic cleaning device into the open end of a gun barrel so that the cleaning device may reciprocably move through the gun barrel and clean it. The cleaning device includes a drive motor, drive rollers, a pair of oppositely rotating brush members and sensing means. The arrangement for introducing the cleaning device into the gun barrel includes a lower trough-like member adapted to be joined to the muzzle of the gun barrel and an upper complementary member which jointly form a composite pipe member having essentially the same caliber than the gun barrel. A centering and tensioning mechanism is mounted on the muzzle of the gun barrel and serves to connect the composite pipe member to the gun barrel in axial alignment therewith. The cleaning device is positioned on the trough-like member and thereafter the complementary member is mounted on the trough-like member and connected thereto.