Distortion measurement circuit

Claim 1

A measurement circuit for use in a telegraphy system having a source of telegraphy signals transmitted at a high rate of step speed to indicate on an oscilloscope with horizontal and vertical deflection circuits the time distortion of successive telegraphy steps caused by differences between the actual and theoretical time durations thereof, comprising: a generator (TG, TU) to produce pulses having a predetermined repetition frequency, first counting means (Z1) connected to the generator to count the pulses produced therefrom, sad counting means having as many different digital counting positions as distortion values to be indicated and operating to count through all of said positions once during each projected step of said telegraphy signal, said first counting means further including means for resetting said counting means and causing same to count all of said positions in a cyclic manner each time, the last of said positions is reached, second counting means (Z2) connected between said first counting means and said generator to count the number of counting cycles of said first counting means, said counting means being settable to a predetermined counting value and including means for deactivating said generator upon reaching said predetermined value thereby determining the duration of the measuring cycle of said apparatuS, means for receiving the telegraphy signal to be measured, storage means (SP) for digitally storing a digital signal representative of the counted value in said first counting means, control means (G) responsive to transitions between successive steps of said telegraphy signal at said receiving means to cause, simultaneously with each of said transitions, transfer of the instantaneous counted value in said first counter to said storage means, converter means (DAU) for receiving said stored digital signal from said storage means, for converting same to an analog signal corresponding thereto, and for applying said analog signal to one of said deflection circuits, said converter means maintaining said analog signal on said one deflection circuit until said storage means receives a signal indicative of a succeeding step of said telegraphy signal, and a source of alternating voltage coupled to the other of said deflection circuits for applying an alternating voltage thereto responsive to a step transition at said receiving means.