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Browse Prior Art Database

Telegraph Code Synchronization

IP.com Disclosure Number: IPCOM000096858D
Original Publication Date: 1963-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Rosenberg, LJ: AUTHOR [+2]

Abstract

A counter keeps in step with incoming telegraph signals by looking for stop-signal SP to start-signal ST transitions.

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Telegraph Code Synchronization

A counter keeps in step with incoming telegraph signals by looking for stop- signal SP to start-signal ST transitions.

Each one of seven telegraph code signals on a data line corresponds to one counter position. Line noise or failures can cause the counter to lose synchronization, i.e., get out of step, with the corresponding telegraph signals. If any signal can be positively identified, the counter can be automatically reset to that signal. Since the stop signal is 42% longer than any other signal, periodic interrogation of the data line coincides with only one transition the stop signal to start-signal, always a mark to space, transition. thus, the stop signal is positively identified and the counter reset, when a mark to space transition occurs on the data line. This prevents, normally undetectable, continuous out of synchronization conditions from occurring.

Assuming initial synchronization, the start signal on the data line sets a start trigger to 1 allowing an oscillator OSC to step the counter. OSC periodically samples the data line, through gate 1, into a measuring arrangement including delay circuit D, inverter I and gate &. These supply a signal E only if the data line signal B changes from mark to space during sampling. This condition does not occur if the counter and data signals are in synchronization. When the counter reaches its last position SP, it resets itself to start and resets the start trigger. Counting starts...