Abstract: A desensitizer apparatus for desensitizing a security sensor element in a book spine. The apparatus includes a scanner which scans along a surface against which book spines are positioned and which detects sensor elements in the spines to be sure that only one book is positioned against the surface. If only one sensor element is detected, a signal is generated which operates a drive mechanism to move desensitizer magnets close to the surface to deactivate the sensor element in the book.

Abstract: Signals received by an electronic article surveillance system are processed digitally to ascertain the variation in magnitude of successive signals and to prevent the actuation of an alarm when the variation exceeds a predetermined amount; and signals whose frequency components have been phase shifted from a filtering operation are restored by passing them into a signal delay circuit, tapping the delay circuit at several points therealong into associated signal channels selectively amplifying or attenuating the signal in each channel and combining the signals in each channel.

Abstract: A clock generator for extracting a clock signal from a data signal includes a timing recovery circuit operable to produce an output recovered clock which is synchronized with transitions occurring at its input. A circuit gates data transitions to the clock recovery circuit input only during time windows defined in a manner based upon the recovered clock. The time windows are produced by comparing the output of an integrator on the recovered clock signal to a reference. The comparator output resets a D-flip flop, to which the data is applied as a clock, the output of the D-flip flop being connected to the input of the timing recovery circuit.