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Threshold-Triggered Filter

IP.com Disclosure Number: IPCOM000060794D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09

Publishing Venue

IBM

Related People

Authors:
Boyd, JB Buhler, OR Call, MG [+details]

Abstract

Both amplitude and time domain qualification of read data which is received from a "pit per bit" optical disk read channel is provided. Read signal 10 is shown in the timing diagram of Fig. 1. Each positive peak of this signal represents a data bit read from an optical data disk. This signal is differentiated (20) so that the data is now carried by the zero crossing of signal 20. Referring to Fig. 2, threshold generator 30 generates a voltage 31 which is some fixed percentage of the peak amplitude of signal 20 (Fig. 1). When signal 20 exceeds threshold voltage 31, integrator 40 begins to charge up from alower clamp voltage. If signal 20 is above the threshold for a minimum time interval, then the output of integrator 40 reaches its upper clamp voltage, thereby setting latch 1, which in turn enables latch 2.