Teletype Corporation

Wayne R Herbst

Paul L Mika

A photoelectric circuit for reading punched data tape wherein the circuit compensates for variations in phototransistors and light emitting diodes, dust accumulation and degradation of the light emitting diodes by comparing the light transmitted through a punched section of the tape to the light transmitted through a solid section of the tape.

Method and means of reading punched data tape

A series of digital words are demultiplexed into two groups and recorded on parallel tracks of a magnetic tape. The digital information is phase encoded upon the two tape channels and during playback the magnetic flux reversals on each channel are separately detected. The peak level of the detected signal is sensed and a peak signal pulse generated corresponding to the occurrence of the peak of the detected signal. Means are additionally included for setting the minimum threshold of the incoming signal necessary to generate a signal pulse so as to provide a level of immunity to system noise. The peak signal pulses are decoded to reconstruct the original data signal and a clocking signal. The data from each of the channel decoders is clocked into respective channel shift registers and multiplexed into its original data word arrangement.

Growing community of inventors

Northbrook, IL, United States of America

Wayne R Herbst