Abstract: A print inspection method in which an area of printed material is optically scanned to obtain image data representing picture elements having variable intensity levels includes counting the number of picture elments at a particular intensity level in the area scanned to thereby generate a frequency distribution of the intensity level of the image data in the area scanned. The frequency distribution generated is compared to a stored reference frequency distribution of intensity levels of the image data. A statistical comparison with the reference data is utilized to determine whether or not the printed material is satisfactory.

Abstract: Head end apparatus delivers video signals, e.g., premium and standard television programming to distinct locations such as hotel/motel rooms, an apartment or the like via a common MATV cable. The head end also transmits digital messages to receivers at each room location which are recovered via a phase detector and supplied to predetermined appropriate output utilization apparatus via a multiplexer and microprocessor. Similarly, messages generated at each room are transmitted upstream to the head end via the cable, employing a portion of the phase detector apparatus.In accordance with varying aspects of the present invention, the bilaterally propagating digital messages may comprise status controls for controlled equipment, e.g., electrical loads; and/or may comprise a data exchange for a communications application. Further, the room transmission apparatus is adapted to fail, if at all, in a noninterfering mode which does not comprise overall system operability.

Abstract: A digital data encoding circuit for use in a one-way transmission system utilizes three 8-bit multiplexers to generate and transmit a 64-bit message. Each bit in the message comprises a 4-chip, or time slot, code that includes an embedded clock therein. The encoding circuit repetitively generates the 64-bit coded message but only enables transmission of one message during periodically recurring intervals. In the event a priority message is sensed, the time between the intervals is reduced so that the rate of message transmission is increased.