Abstract: When digital data are being transmitted, parts of these data can be irreversibly destroyed by channel interference. Gaps produced in this way in the bit stream must be indicated and the respective decoder must be resynchronized. When encoding in accordance with the MPEG2 standard is used, the timing of this resynchronization is heavily dependent on the contents of the bit stream elements which have been lost. Thus, in the event of failure of the picture start codes or extension start codes of the frame layer which are important for the decoding, although the decoder will resynchronize to the slice-start code of the following slice layer, important information such as the time reference of the frame, for example, the frame type (I-, P-, B-frame) or else important parameters relating to the decoding of movement vectors may be false in this case, however.

Abstract: A three-stage system movable in three orthogonal directions includes a pair of cam rods and a screw insertion device secured to one of the stages for displacement in three orthogonal directions. A cabinet has a screw receiving aperture pedestal with aperture locating cam surfaces in a given orientation and spacing. The cam rods are in the same orientation and spacing as the cam surfaces and when engaged align the screw insertion device with the screw aperture. After alignment, a screwdriver attached to the three-stage system drives the screw into the aperture. An automatic feed system feeds screws to the insertion device. A plurality of such three-stage systems are used for automatically attaching an apparatus to the cabinet.