Pulse or digital communications – Spread spectrum – Direct sequence
Patent
1993-08-09
1994-08-09
Chin, Stephen
Pulse or digital communications
Spread spectrum
Direct sequence
375120, 3701053, 328 55, 369 60, H04L 704
Patent
active
053373340
ABSTRACT:
Improved jitter performance is realized in a desynchronizer for obtaining an asynchronous digital signal, e.g., a DS3 signal, from a received synchronous digital signal, e.g., a SONET STS-1 signal. The improved jitter performance results from the use of a unique dynamic bit leaking arrangement in conjunction with a digital phase locked loop and desynchronizing elastic store. An optimum bit leak interval is obtained by controllably leaking a greater number of shorter interval STS-1 bits than the number of received pointer adjustment bits or, alternatively, leaking a fewer number of longer interval bits than the net number of received pointer adjustment bits. Additionally, the affect of random pointer adjustments and the superposition of randomly received pointer adjustments on a periodic sequence of received pointer adjustments is minimized by employing a "static" queue of pointer adjustment bits to be leaked. The queue is dynamically maintained at its "static" count so that there are always bits in the queue to be leaked at the desired optimum bit leak interval even in the presence of randomly received pointer adjustments. In certain applications a fixed bit leak rate is employed in conjunction with the leak queue to control the leaking of bits.
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AT&T Bell Laboratories
Chin Stephen
Ghebretinsae T.
Stafford Thomas
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