Clock recovery system for high density digital tape recorder

The Bit Error Rate (BER) is one of the most important factors determining the quality of a High Density Digital Tape Recorder (HDDR). The main factor contributing to BER is the presence of a drop-out on the tape ie specified time interval during which the SNR is markedly reduced. This loss of SNR has two consequences: a) Increase in theoretical error rate (which can be overcome by the use of error correcting codes). b) Loss of the bit clock in the reproduce channel with a resulting increase in the length of the drop-out due to time necessary to re-establish the bit clock. This paper describes a system which was designed to overcome the effects of this second shortcoming and was subsequently shown to reduce the system cost.