Abstract: A method and apparatus for processing an analog signal before it is converted into steep-sided pulses wherein a variable D.C. voltage is generated whose variation is representative of the change in values of the negative-going portions of the analog signal. A voltage summing means receives on the one hand the analog signal and on the other hand the variable D.C. voltage to provide steep-sided output pulses in synchronization with the "significant" portions of the analog signal.

Abstract: A system for generating and processing pulses representing information, from two pseudoperiodic analog signals along two interconnected channels. Each pseudoperiodic signal is generated by a separate magnetoresistor and is converted in an associated channel into two series of pulses. Conversion is effected by means of threshold switching circuits which control the operation of a bistable flip-flop via a combining circuit. The output of the bistable flip-flop in each channel is cross-connected to one input of a combining circuit in the other channel, the other input of which is a low threshold signal corresponding to the pseudoperiodic signal fed to that channel. The gate produces the logic product of its inputs which drives a flip-flop. The output of the flip-flop is terminated by a reset pulse derived from a zero reset stage.

Abstract: A system for reading coded characters, in particular characters coded in the CMC7 code, includes at least one reading head, two threshold switching circuits which receive output signal from the reading head, two recognition channels which receive signals from the two threshold switching circuits, a multiplexer MX which enables either one or other of groups of outputs from the two recognition channles to be selected, and error detecting circuits which control the position of the multiplexer MX to enable certain reading errors to be corrected automatically.

Abstract: A device for reading printed characters formed of elements separated by spaces of first and second kinds in accordance with a character code. The device includes a read head arranged for relative motion with respect to the elements of a character, and is characterized by being insensitive to the speed at which the character elements move past the read head. The read head includes three element detectors physically spaced such that the first and second detectors are separated by a first kind of space, and the first and third detectors are separated by a distance equal to the second kind of space. Suitable circuitry is connected to the detectors for identifying the two kinds of space. The first kind of space is identified when the first and second detectors simultaneously detect character elements, and the second kind of space is identified when the first and third detectors simultaneously detect character elements.