Fast timing acquisition for partial-response signalling

Details Fast timing acquisition for partial-response signalling Fast timing acquisition for partial-response signalling

1988-08-25

1989-12-26

Griffin, Robert L.

Pulse or digital communications

Repeaters

Testing

341 50, H04L 2534

Patent

active

048902993

ABSTRACT:
An apparatus and a method for fast acquisition of the sample-timing phase in systems using partial-response signalling are disclosed. For fast initial adjustment of the timing phase, a known preamble is transmitted. During that phase, previous schemes could occasionally hang up for an extended period of time at the unstable equilibrium point halfway between the desired sampling times. The new procedure eliminates the hangup problem by introducing a hysteresis effect which greatly diminishes the probability of reversals in the once chosen direction of timing-phase adjustment. Thus, reliable adjustment of the timing phase with a much shorter preamble is achieved. The apparatus for furnishing a timing correction signal .DELTA..tau..sub.n includes a timing gradient generator portion (41) and a data sample reconstruction portion (43). The data sample reconstruction portion (43) develops a present reconstructed data sample x.sub.n from the present received signal sample y.sub.n and a previous reconstructed data sample. The output x.sub.n of the data sample reconstruction portion is delayed and furnished to the gradient generation portion (41) which also receives the present received signal sample y.sub.n and a delayed received signal sample, for generating the timing correction signal .DELTA..tau..sub.n.

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