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Receiver Synchronization for Data Transmission

IP.com Disclosure Number: IPCOM000089906D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Nussbaumer, HJ: AUTHOR

Abstract

In many data transmission devices, the receiver clock is set on the received message or on a particular signal of this message. Very often, the synchronizing signals are generated when the signal corresponding to the message takes a determined value or has a determined variation. These aspects of the signal can occur not only at the synchronization instants but, randomly, at other instants. The correct instants are selected from complementary features of the message signals.

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Receiver Synchronization for Data Transmission

In many data transmission devices, the receiver clock is set on the received message or on a particular signal of this message. Very often, the synchronizing signals are generated when the signal corresponding to the message takes a determined value or has a determined variation. These aspects of the signal can occur not only at the synchronization instants but, randomly, at other instants. The correct instants are selected from complementary features of the message signals.

When the message presents data zones and nonsignificant zones appearing periodically with a period T, it is possible at an instant t to demodulate the received signal by the signal received at the instant t-T. The signal SF obtained constitutes a signal having a level variation when received data changes from one value to the other. If the receiver clock is well-synchronized, SF has a determined level when the clock signals appear. If this is not the case, the clock is to be resynchronized.

Drawing A corresponds to a case where the clock signal is received from the line. Drawing B shows the case where the clock signal is recovered from the data signal.

In demodulator M, the signal entering at In is demodulated by the corresponding signal at instants t-T delivered through delay line T. Signal SF, at the output of M, is squared in Sq and is compared in a comparator Com with the clock signal generated by the clock generator. The comparator delivers,...