Encoder for digital data storage

Abstract

A variable rate bit inserter is provided which efficiently encodes data prior to writing to a magnetic storage medium. In a preferred embodiment, the bit insertion technique monitors the phase and amplitude content of the data stream and inserts appropriate bit patterns to ensure that phase and amplitude lock are maintained on the data stream for reading and decoding purposes. Preferably, the number of bit insertions made on a given randomized block of data is monitored to determine if the number of bit insertions falls within the tolerable limits for storing the data. If the number of bit insertions is not tolerable, the pseudo-random code used to randomize the data stream is reconfigured.

Description

field of invention [0001] The present invention relates to systems and methods for encoding data for storage on magnetic or other data storage media, and in particular, to variable rate bit insertion encoding systems and methods. technical background [0002] Variable rate bit insertion techniques are well known as a method for making a data stream robust to detecting possible errors in the data stream. Typically, this method finds application in the communications field, although variable rate bit insertion techniques have been used in other applications, as is well known in the art. According to this technique, data bits are inserted into selected portions of the data stream in which there is an increased probability of causing errors when the data bits are accurately detected. For example, variable rate bit insertion techniques can be used in communication systems in which the receive decoder is clock-synchronized by itself. It is important that the long string of 1s or...

AI Technical Summary

Problems solved by technology

[0006] In addition to the above-mentioned disadvantages of inserting variable-rate bits in data storage applications, it has been found that traditional variable-rate bit insertion techniques do not always ensure a reduction in loss of phase information and automatic gain control at the receiving end. error caused by

For example, if the detected data stream has characteristics such that the maximum swing in amplitude is not observed over long time intervals, this can cause the automatic gain control at the detection end to lose track, thereby introducing amplitude errors into the detected signal

Moreover, the loss of phase lock may also be caused by data arrangements other than a series of 1s and 0s

So simply inserting a bit into a long string of 0s and 1s does not ensure phase lock is maintained in a self-clocked system on the decoding side

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