Title: Apparatus and method for synchronizing a digital modem using a random multilevel data signal

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Abstract: An automatic digital modem receiving an input analog signal samples the input signal to provide a random multilevel data signal. This multilevel signal is equalized and phase corrected so that the characteristics of the modem are substantially synchronized with the characteristics of the input analog signal. A system error signal which is responsive to the random multilevel data signal is averaged to provide a synchronization quality signal. When the synchronization quality signal degrades to a predetermined magnitude, a restart signal adjusts the sampling, the equalization, and the phase correction of the modem to reduce the magnitude of the synchronization quality signal. The associated method includes the steps of adjusting only the phase correction of the modem for a particular interval of time and then jumping the sampling of the modem if the synchronization quality signal has not been reduced below the first predetermined magnitude.


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