Browse Prior Art Database

Track and Hold Technique for Delay Line Character Recognition System

IP.com Disclosure Number: IPCOM000092504D
Original Publication Date: 1966-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Chittenden, RM: AUTHOR

Abstract

The arrangement in A reduces the sensitivity to time variations of waveform analyzing systems which operate by analyzing magnitudes of waveforms in reference to their position in a delay system such as a delay line. The system operates by tracking the waveform at particular delay line taps and storing the highest absolute value which occurs during a period in which the character waveform passes through a reference position. At the end of the period, the stored values are presented to correlation networks for subsequent analysis and decision.

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Track and Hold Technique for Delay Line Character Recognition System

The arrangement in A reduces the sensitivity to time variations of waveform analyzing systems which operate by analyzing magnitudes of waveforms in reference to their position in a delay system such as a delay line. The system operates by tracking the waveform at particular delay line taps and storing the highest absolute value which occurs during a period in which the character waveform passes through a reference position. At the end of the period, the stored values are presented to correlation networks for subsequent analysis and decision.

Switches 5 and 7 are open as the character waveform approaches the reference position. Capacitors 6 and 8 are charged in accordance with positive or negative-going excursions of the signal. The latter is supplied via terminal IN, an amplifier and steering diodes. Capacitors 6 and 8 charge to the peak output voltage of the delay line tap. Switches 9 and 11 are then momentarily closed. The voltage stored on capacitor 8 is inverted and both voltages are fed to the inputs of the comparator. This passes the largest of the two in absolute value and associates the proper polarity on the output. After this time, switches 9 and 11 are opened and switches 5 and 7 are closed to prepare the circuit for the next cycle of operation.

In B there are shown samples of waveforms as can be encountered in operation of the system. Waveform a shows the leading peak of a waveform a...