Abstract:
Presented is a receiver in a data read channel having an input terminal for receiving an input signal provided by a transmitter of the data read channel, and producing an output signal at an output terminal, the receiver comprising:
a finite impulse response (FIR) filter coupled to the input terminal and having filter coefficients capable of being adapted; an interpolated timing recovery circuit coupled to an output of the FIR filter, the timing recovery circuit having an output signal coupled to the output terminal of the receiver; a timer circuit coupled to the output terminal and feedback connected to the timing recovery circuit; wherein the coefficients of the timing recovery circuit are dynamically adapted using a cost weighted function through a signal power spectrum of the data read channel.
Abstract:
The invention relates to a control signal compensation method particularly intended for an analog/digital processing system provided with a control loop, including in turn a controller (5) and a monitoring (4) circuit, characterised in that it comprises the following steps:
storing the corrections made by the controller; fast processing such corrections in advance of the transmission of the corrections throughout the control loop; generating a compensating signal (014) for the latency effects of the controller, by the use of a negative feedback loop provided at the monitoring circuit level.
The invention also concerns a compensation control system implementing the above method, and an analog/digital processing system incorporating such a compensation control system.
Abstract:
The invention relates to a method and architecture for improving the robustness of a synchronization system through a minimum latency loop, for instance in the Hard Disk Drive applications, wherein synchronous detection processing is performed for timing recovering of a correct sampling phase and frequency and by a first acquisition step of the a known preamble signal pattern, for generating a timing periodic signal, followed by a second tracking step, for recovering phase, frequency and gain sampling errors of the synchronization signal including a header followed by an unknown data content. Advantageously, a feedback loop including a numeric preamble generator (NPG) is provided for obtaining a reduced latency in the acquisition phase; such a numeric preamble generator (NPG) stores preamble values for different phase offset.
Abstract:
A method to improve data reliability on Hard Disk Drive systems wherein user data items are distributed across a set of independent sectors and appended to a header in order to ensure adequate signal amplitude and synchronization and wherein a first timing recovering phase is achieved to recover proper signal amplitude acquiring phase and frequency lock by a preamble field and a subsequent frame synchronous detection phase acquiring a sync mark field. The method takes advantage of at least a data sector comprising a first header including a first preamble and a first sync mark field and a second header including a second preamble and a second sync mark field.
Abstract:
In the MSN encoded form, the symbols of each block define a running digital sum (RSD) value, defined as RDS ([a 0 a 1 ...a N-1 ]) = - Σ 1 (-1) i a where the symbols a i belong to the set {0,1} and the sum extends for values of i from 0 to N-1. The encoder (16) is configured to satisfy at least one of the following characteristics:
a) blocks of symbols with a given length (L) are used for encoding, wherein
RDS = RDS 0 + 4.K, where K is an integer, RDS is the said running digital sum, RDS 0 is defined as zero for even values of the said length (L), and one for odd values of said length (L), and
b) blocks of symbols with a given length (L) are used for MSN coding and encoding is effected by selecting encoded blocks such that the set of running digital sum (RDS) values is the set with the minimum number of elements that satisfy the required rate value, defined as the ratio between the length of the input blocks and the length of the output blocks.
Abstract:
A system (10) for decoding digital signals subjected to block coding (B) comprising a post-processor (13) which corrects (13) the codewords affected by error, identifying them with the most likely sequence which is a channel sequence and which satisfies a syndrome check. The post-processor (13) is a finite-state machine described by a graph (G) which represents the set of error events (E), the set of respective transitions defining the structure of said set of error events. Preferably, the post-processor (13) evolves in steps through subsequent transition matrixes (G), deleting at each step the following graph paths
paths which accumulate an invalid number of error events (N E ) or an excessive number of wrong bits (N), paths which accumulate a total reliability higher than a given threshold (β), paths with a invalid check on the received sequence (P), and paths which reveal an invalid syndrome (S) after having reached a maximum number of events.
Abstract:
The present invention relates to a method and apparatus for detecting and correcting errors in a magnetic recording channel of a mass storage system, that combines a Soft Output Viterbi Algorithm SOVA (39), having the capability of detecting the reliability of a discrete, equalized signal (38), and a post processor (37), having the capability of detecting specific error events in said discrete, equalized signal (38), so as to correct said error events and to generate an output bit stream (48).
Abstract:
This invention relates to a method of optimising a PRML (Partial Response Maximum Likelihood) receiving channel (2) for mass memory data receiving systems comprising an input receiving channel (2), a receiver (3) placed downstream of the channel (2), a detector (4) connected in cascade to the receiver (3), and a summing node (11) being input both the receiver output ( p(D) ) through a delay line (10), and the output from the detector (4) through an impulsive filter (12), which method is characterised by:
performing an indirect estimate of the noise strength p(D) by filtering out the error sequence ( e(D) ), i.e. the output signal from the summing node (11), through a filter (21); and selecting either the output from the summing node (11) or the output from the filter (21) to obtain an optimisation parameter (ACCout) for feedback to the receiving system.