Automatic curve reading by phase-modulated analog sampling

Coincidence pulses generated upon sinusoidal scanning of a curve originally recorded optically (e.g., ink-on-paper, photographically) trigger a sample-and-hold circuit having the scanning waveform as an input; a sampled electrical version of the original curve thus results. This principle is readily adaptable to simultaneous multichannel operation for continuous automatic reading of electroencephalograms, seismograms, etc.