Abstract: A data read system comprising a read channel for processing a signal, and a diagnostic controller in communication with the read channel. The diagnostic controller is configured to measure at least one metric of the read channel during processing of a signal containing unknown data. The measured metric is then compared against a stored nominal metric and a warning is generated in response to a result of the comparison. In particular, the warning is generated only if the difference between the measured metric and the stored nominal metric exceeds a threshold.

Abstract: A tape drive apparatus has at least one rotary head for reading/writing a track. The track has a number of fragments and each fragment has an identifier. The tape drive apparatus has a position indicator apparatus for providing a signal that indicates a rotational position of the head. The combination of the signal and the identifier unequivocally identifies a fragment within the fragments of a track. This has the advantage that non-unique identifiers can be used for the fragments of a track.

Abstract: Encoded data is decoded by a receiver for an analogue input signal that is converted into a digital signal. A detector produces a sequence of data representative of the analogue signal, a decoder for the sequence of data outputs data indicating that a sequence includes an error. An event detector detects an event which substantially alters or destroys the analogue input signal. The decoder outputs data corresponding to the or each sequence resulting from the altered or destroyed analogue input signal indicating that the sequence is incorrect.

Abstract: Encoded data is decoded by a receiver for an analogue input signal that is converted into a digital signal. A detector produces a sequence of data representative of the analogue signal, a decoder for the sequence of data outputs data indicating that a sequence includes an error. An event detector detects an event which substantially alters or destroys the analogue input signal. The decoder outputs data corresponding to the or each sequence resulting from the altered or destroyed analogue input signal indicating that the sequence is incorrect.

Abstract: A method of controlling an adaptive filter in a data channel carrying a signal from which data is to be recovered, the filter having an associated coefficient store and a coefficient temporary store, the method comprising the steps of: